houdini adventures

PBR play

2011-12-28T00:59:00.000-08:00

Links updated

2011-12-20T17:27:00.001-08:00

old links deleted - a couple of new links added...scroll down. check em out !

Halftone SOP

2011-12-12T18:35:00.000-08:00

Time to dip my toes back in the water of Houdini.here i just look at an image in cops with pic or picni and colour my template points accordingly, then copy a group of 4 discs to each point.

template points

I then use a switch with a stamp expression to swap between the circular disk configurations
that give the impression of more or less black ink. Only 5 variations here.

5 disc groups for the switch SOP

Render of discs

Happy Feet 2...winding up

2011-10-19T05:06:00.000-07:00

...it seems ive just about finished working on Happy Feet2,
my first contract on a fully animated feature.

It's quite surreal. Suddenly after the last few weeks of intense 12 hour days, 7 days a week...there is nothing to do ? Currently im waiting (watching EdCatmull talking about successes and failures in the industry) for what could be my final shot , my final input to the film to be given the final review - so i can publish the particle FX and it can move down the pipe and be lit and rendered, and comped for the final output.

With out sounding pompous, I should thank a few people. Ben Simons and Rangi Sutton for giving me the chance to work on this amazing feature. Dave Brown, Rob East, Christian Hernandez and Sam Hodge for also giving me references to get a foot in this door. Thx guys.

Thanks to Jason Simmons, Goncalo Cabaca and Marc Picco for putting up with me....sometimes I slightly bash my keyboard when things dont go right :)

Definitely a learning experience, and quite a frustrating one. I'm very glad its almost over. All of the imagery I've seen in the system is looking spectacular, so definitely go and see it at the cinemas !

teaser trailer:

http://www.youtube.com/watch?v=twYq5QkNPKw

DrD ! featured on SideFx

2011-07-21T01:04:00.001-07:00

www.sidefX.com

linux commands repo

2011-07-20T16:34:00.001-07:00

linux commands will be collated into one post here
linux commands

fur renders

2011-06-09T01:19:00.000-07:00

Volume SOPS

2011-06-05T01:41:00.000-07:00

checkin out the volume SOPS..

basic volume SOP

allows for scalar or vector or matrix volume

allows you to specifiy a name and value,

sampling and Tapering which i havnt seen before.

from the help:

The grid generated by the Volume SOP has constant value everywhere. It can be further manipulated on a voxel-by-voxel basis using the Volume VOP SOP or the Volume Mix SOP.

When mantra renders volumes it overrides rendering parameters according to the name of the volume. This name can be set in the Volume SOP (or later using the Name SOP). The name is also used for the default bindings to the Volume VOP SOP.

If you connect geometry to the Volume SOP’s input, it will create a bounding box around the input geometry.

Volume Analysis

from the help :

Computes analytic properties of volumes....

such as the gradient and curvature. This is done in the local space of the volume. These are a function of more than one voxel so are more difficult to compute inside a Volume VOP.

Where possible, these operations occur in place and preserve the name. If new volumes have to be created, it is attempted to ensure they gain the .x, .y, .z style suffixes in their name attribute.

an Attribute from Volume SOP transfers the curvature attribute to the geometry

Cd is simply specified in the SOP under attribute name.

Volume Blur

The Volume Blur operation blurs the voxels of a volume.

Volume Break

Cuts polygonal objects using a signed distance field volume.

Volume Compress

Volumes can be very big. The Volume Compress SOP makes it easy to make a size/quality trade off for volumetric data.

Volume Feather

The Volume Feather operation smooths the edges of the scalar data in volume primitives. This is done either in an inwards or outwards direction. It sets the maximum rate of change in the volume, clamps either increasing or decreasing transitions, and can be thought of as a one-sided blur.

Pyro Masterclass Slides

2011-05-30T02:13:00.000-07:00

Level Sets

2011-05-29T21:30:00.001-07:00

wikipedia

http://en.wikipedia.org/wiki/Level_set

Pyro Solver

2011-05-29T21:29:00.000-07:00

My posibbly dodgy NetBox / Node description:

--------------------------------------------------------------------------------

Create Source Mask

involves GasBuild Relationship Masks

help:

"A microsolver that builds a mask for each voxel to show the presence or absence of relationships between objects. It builds a mask field that represents where the affecting objects

intersect with the fluid."

Theres a switch which switches between 2 GBRM (Gas Build Relationship Mask) Nodes - 1 with an index field set to source index, and the other without.

Index Field help:

"An optional index field which is set to the object id of which object was closest to the given voxel and within the bandwidth distance."

Both of these nodes use density as a reference field.

the switch has an expression as follows:

(ch("../sourcevelmerge") != 0) || (ch("../sourcetemperaturemerge") != 0)

so the switch takes the second input (input id1) if sourcevelmerge is not 0 or

sourcetemperaturemerge is not 0.

looking at the top level of the pyro solver - we can see these parms

under advanced/solvers.

Vel merge gives us the options

(0) None,

(1) Weighted Average,

(2) Net New Source

Source Temperature merge (sourcetemperaturemerge ) gives us

the same menu options.

So an index field is added if either of these are not zero, ie the switch is activated.

What does the index field actually do ?

The Create Source Mask NetBox also has a noise node followed by a switch.

"Add Noise" is a Gas Field VOP (GFV).

help:

"...the Volume VOP runs CVEX over a set fields. The CVex Shader can be defined as a .vfl file, a SHOP or by building a CVEX VOPnet inside this node - the most straight forward approach."

We can dive inside of this VOPnet and we see...

if source > 0 then..

if anysource != 0 then...

multiply by aaflow noise and mix this in with Amount parm

the switch following this is driven by !ch(../dosourcenoise)

which is the toggle at the top level - sources/ noise/Add Noise (toggle)

so summing up this box basically allows noise to be mixed into the source

and allows it to be turned on or off.

--------------------------------------------------------------------------------

Apply sources

switch to apply velocities ch("../sourcevelmerge")

driven at the top level by Advanced / Sources / Apply Vel Merge

The options are

None (Null)

source_vel_wavg (GC -Gas Calculate)

source_vel_netnewsource (GC)

Apply temp looks similar - a DOPS switch - note the icon is like a GC node

to apply different temperature situations

(0) No temp change

(1) source temp weighted average

(2) source temp net new source

--------------------------------------------------------------------------------

Gas Calculate Node

from the help :

"A microsolver that performs general calculations on a pair of fields....

The Gas Calculate DOP performs many different operations on a pair of fields. It can be used to scale or blend two fields.Another use is to find the intersection or union of signed distance fields by using the Maximum or Minimum function."

2 more switches add the data for mix in source density and fuel.

--------------------------------------------------------------------------------

Add Fuel Model

the fuel model node /asset is a Gas Combustion Node

we can jump in and we see several GCalc nodes

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Gas Comb help:

"A microsolver that applies a combustion model to the simulation."

GComb is working with several fields

Temperature

Fuel

Soot

Divergence

Burn

--------------------------------------------------------------------------------

Enable Fuel Model

This is simply a switch to enable or disable Fuel, driven by

1 - ch("../docombustion")

(top level toggle - simulation/combustion/Allow Combustion)

--------------------------------------------------------------------------------

Calculate Force Scale

Constant Scale - GCalc

Build Force Scale - Gas Field VOP

Blur Force Scale - Gas Blur

--------------------------------------------------------------------------------

Gas Blur - from the help

"A microsolver that blurs fields....using an optionally time dependent blur kernel."

What does it mean by time dependent blur kernel ?

--------------------------------------------------------------------------------

Velocity Update

this netBox contains many nodes...

Buoyancy

Gas Buoyancy Node

from the help...

"...A microsolver that calculates an adhoc buoyancy force and updates a velocity field..."

"The Gas Buoyancy DOP calculates an approximate buoyancy force dependent on the temperature field and updates a velocity field according to that force."

"Given an ambient temperature Ta, temperature T, buoyancy lift l, and buoyancy direction of B, the force will be: ((l * (T-Ta)) * B "

--------------------------------------------------------------------------------

Viscosity Node

"A microsolver that diffuses a field or point attribute...

The Gas Diffuse DOP performs a diffusion operation on the field. This will smooth out sharp discontinuities and spread out the values of the field. On vector fields, such as a velocity field, this can simulate viscosity as each voxel’s velocity will be affected by its neighbor’s values."

--------------------------------------------------------------------------------

Vorticle Forces - the Gas Vorticle Force Node

"A microsolver that applies forces to a velocity field or geometry according to vorticle geometry.

The Gas Vorticle Forces DOP applies paddlewheel like forces around each vorticle according to the vorticles attributes.

The purpose of vorticles is not to create new forces, but to maintain vorticles that naturally occur and prevent them from dissipating due to artificial viscosity.

The pscale attribute is used to determine the radius of influence of the vorticle. The up attribute is used to determine the orientation of the paddlewheel. The mag attribute is used to scale the force of the vorticle.

--------------------------------------------------------------------------------

Turbulence

has a bunch of nodes combing to form the turbulence Node (a switch)

No Turb - simply a null

switch 16 - driven by "align turb calc"

- switches between compute turbulence alone (GFVop) and 4 nodes merged.

4 Merged Nodes:

Compute Turbulence

CreateForce Vel temp

Add Force Vel Temp to Vel

Clear Force Vel temp

Compute Turb - Gas Field VOP

We can dive into this and we see...

TimeStep is a volume VOP

looking at the globals for a Volume VOP will help us to understand this stuff.

P - position of the current Voxel

Densisty- the value of the density field art this voxel location

ix,iy,iz voxel indices - ranging from 0 to (res-1)

res[]x,y,z] - resolution of the current volume

Center - the center of the current Volume (not voxel)

Orig (in) - the bottom left corner of the current volume

Size - the size of the current volume

dPd[x,y,z] the derivative od P - these vectors store the change in P that5 occures in each step for x,y,z and voxel indices.

BB position iside the Bounding Box of the Volume - each coordinate ranges from 0-1.

Time the glo0bal time when the Vol is being evaluated

Time Inc - the timestep currently being used by the sim or playback

Frame - the current Frame being processed - NB this can be fractional.

So in this VOPnet

if amp or ramped amp of Force Scale is not very close to zero, use curl noise.

This result is multiplied by the timestep and the forceScale parm, then added to the incomuing velocity. Roughness for the curl noise can also be ramped.

i[x,y,z] as a vec is divided by res[x,y,z] as a vec to give BB (vec)

dPd[x,y,z] are individually multiplied by resX and -.5

and the lengths of these vectors are then output to a new vector which becomes the new SIZE.

They are also added together to give the origin.

This VolVop has DataBindings - they seem to link DOPS data with a Vex parameter.

here forcescale (DOPSdata )is being linked to forcescale(as a vex parameter)

and..

forceveltemp and vel DOPSdata is being 'linked to' vel as a VEX parm

(if align turb calc is on)

--------------------------------------------------------------------------------

CreateForce Vel temp - Gas Match Field

from the help:

"A microsolver that rebuilds fields to match in size and resolution to a reference field.

The Gas Match Field DOP creates, resizes, and resamples as necessary to ensure the data matching the given name exists as a field of the same resolution and size as the reference field.

This DOP is very useful for creating adhoc fields that you need for intermediate results but don’t want to explicitly attach with the Scalar Field DOP. If you want to remove the adhoc field when done, you can zero it out. Constant fields are compressed so do not have the memory footprint of a varying field."

The reference field is vel...

--------------------------------------------------------------------------------

Add force vel temp to vel node (Gas Calculate)

destination field: vel

source field: forcevel_temp

source property: friction

calc : add

Clear force vel temp (Gas Calculate)

destination field: forcevel_temp

source field: none

source property: friction

calc : copy

--------------------------------------------------------------------------------

Speed Limit DOPS

doSpeedLimit is an enabling switch between :

noSpeedLimit ( a null DOP)

and minSpeed and maxSpeed - merged.

Min Speed and maxSpeed are both Gas Calculate Nodes.

--------------------------------------------------------------------------------

Build and Apply Sink

Build sink mask (Gas Build Relationship Mask) just like Source Build

merged with Remove Sink Density (Gas Calculate Node)

--------------------------------------------------------------------------------

Build Collisions

Build Collision Mask (Gas Build Collisions)

help:

"A microsolver that determines the collision field between the fluid field and any affector objects.

The Gas Build Collision Mask DOP builds a collision field that represents where affector objects overlap with the fluid field. It generates a signed distance field which is negative inside colliding objects and positive outside. It also generates a collision velocity field that stores the velocity of the affector object closest to each point."

this is merged with a apply collide temp switch which simply switches between not temp

and temp applied to colliders (Gas Calculate DOP)

--------------------------------------------------------------------------------

Create and Apply Pumps

just like sinks and Collisions above, we have a Gas Build Relationship Mask

that builds the Pump mask and Pump relationship using a index field and a reference field (density).

Also merged into pumps is a switch Solver which is controlled by the top level parm

"pVelMerge".

help:

"The Switch Solver DOP allows simulation objects to be solved by one of several solvers connected as subdata to the Switch Solver. For each object, the solver to use is determined by the value of a Switch Value data attached to it. Unlike the Blend Solver or Multiple Solver, only one of the sub-solvers is applied to each object."

...and there is also a switch (not a switch solver) between no temperature and a pump temperature (set pupmp temp) Gas which is a Calculate Node.

These are merged together to form "Pumps" - a merge node.

--------------------------------------------------------------------------------

Velocity Advect

Gas Advect DOP

help:

"A microsolver that advects fields and geometry by a velocity field.

The Gas Advect DOP evolves fields and geometry according to a specified velocity field. The fields and geometry will be moved by the velocity field for a distance proportional to the current solver timestep."

--------------------------------------------------------------------------------

temp Project Velocity

--------------------------------------------------------------------------------

Field Advect

contains many nodes...

from L to R going into the merge node...

Rest Advect (Gas Advect DOP)

Diffuse Heat (Gas Blur DOP)

Cool Gas (Gas Calculate DOP)

Advect Vorticles (Gas Advect)

Stretch Vorticles (Gas Velocity Stretch)

Compress Fields (Gas Velocity Stretch)

with enable switch below it.

Diffuse Smoke and Diffuse Fuel nodes (both Gas Blur DOPS) merged

Heat Source - itself a null hook being fed by...

1. a null - no heat

2. from source - source to heat (Gas Calculate) merged with "Age our old heat" (also Gas Calculate)

3. from burn another merge - merging Burn to heat (Gas Calculate again) Age_our_old_Heat

Fuel Advect

(Field Advect (Gas Advect DOP) merged with Advect Fuel

(Gas Advect DOP) merged with itself again.)

Advection Stage (input 4 from Pyro's top level inputs (the 5th and final input))

Extrapolate into Collisions with a switch enabling / diabling.

(Gas Extrapolate DOP)

help:

"The Gas Extrapolate DOP extrapolates a field value along an SDF. The field’s value at an isosurface will be copied outwards along the increasing direction of the surface field."

Clamp inside Density (Gas Calculate)

merged with

Clamp inside Fuel (Gas Calculate)

The final merge is "Field Update and Advect"

--------------------------------------------------------------------------------

The Pyro Object is brought in - and all solver data is deleted from it with a delete DOP named

"rebuild solver"

NB no objects are deleted - just data.

this is piped into the objects pipe of a multi-solver

MultiSolver help:

"The Multiple Solver DOP causes a simulation object to be solved by more than one Solver at each timestep. Each solver attached to this node is applied in order to the object.

Many solver combinations will produce strange or unexpected results. For example, applying two RBD Solvers will simply make objects move twice as fast.

The most useful solver combinations are ones where each solver acts on a different piece of data on the object. For example, the RBD Solver alters the Position data of an object. This may be followed by a SOP Solver that modifies the geometry of the object based on the position, velocity, or impact information generated by the RBD Solver.

It is important that you make sure the attached solvers have different names. Solvers by default all have the name “Solver” and will thus overwrite each other. The Unique Data Name toggle on the incoming solvers can be used to ensure that the names are different."

The data going into the data pipe of the multisolver (from left to right) is:

1. the gas substep node containing all the gas advection etc mentioned above.

2. 'Data to attach' - the 5th and final input from the pryo solver top level inputs

3. Clear fields (a merge DOP described below)

--------------------------------------------------------------------------------

Clear Fields

has a switch feeding into it, switching between 3 nodes.

1. null1

2. clear hidden (Gas Calculate Node)

3. clear Static (Gas Calculate Node)

this is merged with a another Gas Calculate Node 'Clear Additional'.

at the top level of the Pyro Node under Advanced /Clear
we have a drop down menu giving us our three choices to clear no fields, hidden fields or Static fields...and we have a 'text field' to type the names of any additional custom fields we may want to delete.
--------------------------------------------------------------------------------
After the Multisolver we have a Drag force with a switch enabling or disabling it.

..and a null.
--------------------------------------------------------------------------------
so in summary - its not as bad as it looks...

The Gothic

2011-05-27T03:55:00.000-07:00

FX in developed at Kanuka Studios in conjuntion with 50/50 Studios, Brisbane.

Volume Tools developed by Rangi Sutton / Kanuka Studios.

FX Shots worked by Rangi and myself.

some screen captures ! :D

VOPS play

2011-05-03T06:13:00.000-07:00

here's some images made procedurally with VOPS...

Chocolate !!! :D

2011-04-27T22:53:00.000-07:00

WIP

viscosity needs work
peanuts need a texture, need to re-sim the chocolate to fix the wierd red hole on the facing corner.

ALL SYSTEMS GO !

2011-04-24T21:46:00.000-07:00

some more copy-stamping fun for the easter break.

Button width and length and height,
as well as a switch to make the button green or red is random.

new render has a switch for round buttons as well, and some proper DOF.

AmbOcc

Beauty

SSS

Comp

Comp2

UTS Test Images

2011-04-22T16:13:00.000-07:00

As mentioned last month ive been working on a test for a TVC, amongst the training videos and Kanuka stuff.
This morning I received an email saying the client wants to take it further which is very exciting. Would also be nice to be back paid for the 3 weeks work i put in.

here's some images in no particular order:

initial plankton test

bubble test

- need a better HDRI image

splash from above

- pops and metaballs - but no skydome - hence the black reflections

splash from above

- pops and metaballs with skydome as phantom
for better reflections

Fish Eye lens Effect from Vray - color corrected in COPS

Vray / TurboSquid pre-rolled ocean

My splash popnet - showing particles colliding and sticking with

the animated ocean surface in orange.(from the side)

FLIP splash sim (from above)

IOR Table

2011-04-03T04:51:00.000-07:00

from BlenderArtist.org - cheers !
http://blenderartists.org/forum/showthread.php?71203-Material-IOR-value-reference

Material IOR value reference

Hi, i have listed some 'RayTransp' material 'IOR' values.

Material IOR Values:

'Air': 1.000
'Bubble': 1.100
'Liquid methane': 1.150
'Ice(H2O)': 1.310
'Water': 1.333
'Clear Plastic': 1.400
'Glass': 1.440 - 1.900
'Light glass': 1.450
'Standart glass': 1.520
'Heavy glass': 1.650
'Obsidian': 1.480 - 1.510
'Onyx': 1.486 - 1.658
'Acrylic glass': 1.491
'Benzene': 1.501
'Crown glass': 1.510
'Jasper': 1.540
'Agate': 1.544 - 1.553
'Amethist': 1.544 - 1.553
'Salt': 1.544
'Amber': 1.550
'Quartz': 1.550
'Sugar': 1.560
'Emerald': 1.576 - 1.582
'Flint glass': 1.613
'Topaz': 1.620 - 1.627
'Jade': 1.660 - 1.680
'Saphire': 1.760
'Ruby': 1.760 - 2.419
'Cristal': 1.870
'Diamond': 2.417 - 2.541

ocean surface test

2011-03-17T07:17:00.000-07:00

Ive started a pitch for a TVC which ive dubbed UTS - under the sea...
which also involces an out of water shot of the ovean surface and a splash
- so heres a test ive done.

havnt used HOT yet - may possibly get it going in Maya...

pretty happy with this so far though ! :D

some obvious problems -

* some crunchy pixels from a bad slap comp (its past midnight)
* you can see the 'tiling' of my noise
* reflection of buildings is hacked in
* you can see the seam between the CG ocean and the BG photo....its just a test...
* render settings could be higher...
* i dont know how or why i animated my hacky DOF :/

but....shows promise !!

cheap flocking effect with a school of fish

2011-03-12T16:20:00.000-08:00

some tests for flocking

panorama lens test

2011-03-08T22:02:00.000-08:00

testing the polar panorama lens, the big tree is a render from a normal perspective camera, the little trees stacked on top of each other are the same trees - but as viewed through the polar lens (panoramic) projection.

here's a render with a sphere behind the camera and some objects - Left and Right of the camera.

This is not a fish eye lens effect - its the opposite.

ABC stout

2011-03-04T02:25:00.000-08:00

** final ad now on youtube **

http://www.youtube.com/watch?v=4WK2bh5vIno

A crazy Ad ! in conjuntion with Kanuka Studios and

Emerald City

My role was to develop some Lava Sims to be comped into the Matte Paintings by Emerald City.

I also did some rough modeling, some rigging, some lighting ,

and even some rough animation ! all in Houdini.

From the start we decided to go with FLIP fluids for the lava sims.

Thanks Jeff Lait for your excellent, invaluable MasterClass.

a lava sim - not used in the ad...

mplayer / ffmpg misc brain dump

2011-02-08T01:51:00.000-08:00

to get it looping - use -loop 0

ie
mplayer ../playblast.avi -loop 0

procedural cracking !

2011-02-07T04:23:00.000-08:00

heres a procedural cracking test - no DOPS as yet

very simple - a proximity driven morph (from the boulder)

more or less bewteen 2 SOPS.

Cracks generated in 2D by the Voronoi SOP.

what ive been reading....

2011-01-27T18:36:00.000-08:00

Still on holiday , so sorry, no serious 3D posts yet...

some VFX from the Black Swan
http://www.vizworld.com/2011/01/black-swan-visual-effects-video-reel/

sony stock footage - new spiderman 2 footage of manhatten
https://www.sonypicturesstockfootage.com

vfx guide have an article on the HP7 animation (the story of the 3 brothers)
http://www.fxguide.com/

do it yourslelf HDRI
http://nccasymposium.bmth.ac.uk/2008/ahsan_zohaib/How.html

CIS Vancouver
http://www.cisvfxgroup.com

why cant i run firefox in ubuntu ?

back up the files in the home directory / mozilla / firefox
then delete them
or just move them to a new folder like 'bak' or something

chromatic aberration post from aeons ago updated...

2011-01-20T03:36:00.000-08:00

see old chromatic abherration post...

updated with link to fantastic photography from Andrew Schneider...

im still here !

2011-01-20T02:53:00.000-08:00

Happy New Yr, Happy Brthday to me, thank you to all whom made it fun,
just thought id pipe in and let ppl know - if anyone still reads this blog....that ive been resting and relaxing and im still alive - and plan to get back deeper than ever into learning new stuff in Houdini and sharing it here :)

Thx Raph and Fi, for the holiday ! the surf was awesome !!!
Photos soon....

Prido project update

2010-11-11T17:22:00.000-08:00

prido project underway again...see prido

back to Brisbane

2010-10-25T22:29:00.000-07:00

...from Harry Potter to Polly Pocket :) whats next...I wonder.

This job is giving me some nice time to think about lighting using spotlights to fake GI.
And im getting some nice renders...

I've also taken the time to dabble in a little MaxScript to try to optimise our workflow.

My scripts make selection sets of the characters and sets and props so we can easily orgainse the lighting.
Another script sets up the 'light linking' or Include/Exclude Lists for characters to remove hoo-man error and ensure the lights are only effecting what they should be.

Other scipts swap out shaders to account for updates in character models, and keep things streamlined.
Some test renders coming soon....(20/1/11)

bit of humor

2010-09-06T23:10:00.000-07:00

Im at home sick today when i should be at work, working on the latest Harry Potter movie !
so some humor is in need - from swann - thnx on the side effcts forums.

RSP featured on CGSociety !

2010-09-04T20:56:00.000-07:00

Rising Sun Pictures featured on cgsociety

procedural feather

2010-07-14T18:05:00.000-07:00

the beginnings of a procedural feather generator

stuff I've though about so far:
proxy / hi res toggle - currently the 'fronds'can be turned off but ideally it'd be nice to have a few polygons with the render UVmapped on automagically

the user can adjust :

the position along the stem where the fronds start
the sweep thickness of the stem via ramp
the poly detail of the stem
the overall shape of the fronds via a ramp
the angle fronds grow out and down toward the base of the feather
vs how perpendicular from the stem they are
the number of fronds and the detail of the curves
the render width of the fronds / curves.
the thickness of the individual fronds via a ramp
the noise on the fronds
the overall bend and twist of the feather

Further stuff i want to have a crack at:

a procedural colouring system based on real feathers
subtle randomisation tests on most parameters
irridescent shading
a texture generation system for low res geometry.

UN-subdivide

2010-07-11T16:31:00.000-07:00

rob kelly nutted this out for me...

put in a subdivided mesh with no history...and get the UN-subdivided equivalent out of it.

he uses a VOPSOP that counts how many neighbors a point has, and if it has 4, then
it can be removed. The trick is to delete every second face first , then check every points neighbor count,
then on another version, delete every second face/prim - but starting from prim #1 as opposed to prim #0,
then repeat the neighbor count and point removal.

Combining the two results gets you the un-subdivided mesh.

The example file is on odforce here, and shows two methods of achieving the same result.

nice work Rob Kelly ! :)

NOKIA E60 rendered with Mantra

2010-07-07T02:17:00.001-07:00

inspirational links updated

2010-06-30T00:32:00.000-07:00

see march

SOP renderer of sorts...

2010-06-23T19:20:00.000-07:00

inspired by ben p's blog

http://blog.ioxu.com/?p=572

a SOP land 'renderer'

below - the 'secne' as rendered normally, and the 'render' :) from the SOP renderer...

annd finally - the '3D pixels' - boxes copied onto points.

the scene

colour info through the ray SOP

the 3D pixels rendered from a different angle

lighting info from the phong shader equation. basically the dot prod of the surface normal

and the light position - multiplied by the light's multiplier, and added to the diffuse colour already present.

'champix' plasma

2010-06-21T03:44:00.000-07:00

Whist at Cutting Edge, I worked on developing some Plasma effects.

The plasma was to 'arc' between the packet of cigarettes and the inner bell jar

walls. The arcs were also to travel around a little and change positions after a certain amount of time.

This could be achieved several ways - but time was short so I belted out this solution.

The plasma needed to have two contact points, so i used scatter to generate points over each object - the bell jar and the box inside it - to use as a base for the contact points. I then used a sort to randomise the point numbers so that when the seed is changed - the point numbers change. When the arc of plasma uses just one of these points as a template or contact point, this can be animated randomly simply by changing the seed.

The important part - was to change the seed every few seconds only - not every frame. I used the expression:
int($F/25) in the seed parameter of the sort SOPS. As the animation plays - every 25 frames, the expression grows by a value of one.

I used a line copied to one point only of the scatter SOP as the foundation of the arc of plasma. At this stage in the network - the line only has 2 points - a start point and an end point. The other point is then 'rayed' onto the box that sits inside of the bell jar.

So now I have straight lines that seem to randomly change both at the start and end point positions - yet are always touching the surface of both the box and the inside of the belljar. So now i need some noise, but in order for the noise to get results - I also need more points. After resampling - the noise is achieved in a VOPSOP with Turbulence added to the original point position.

The noise creates pseudo random movement - and moves some points away from each other more than others - creating different lengths of line segments with in the line. I decided to resample again after this just to get a nice consistency of length in the line segments.

One interesting aspect I have in this SOP network that I didn't use in the original TVC was the third sort SOP that causes the point numbers to shift and wrap around down the line. this allowed me create an effect or energy actually traveling along the line from the belljar toward the box inside it. To achieve this I had to give random colours based on the points and then create groups from this. This forced the newly assigned point colours to follow the motion of the changing point numbers and thus travel along the length of the line.

To accentuate this I swept a grid along the lines to create tubes and then 'peaked' out only certain points from my group that cause a little bulge to travel down the line. In this network I have disabled the sweep, as I realised this could probably be done with mantra and the width attribute.

So now I had one plasma arc buzzing and popping around - so a copy SOP allowed me to duplicate this around and stamping allowed me to randomise the noise seed so each arc was unique.
Stamping was also used to to offset the animation timing and point colour assignment.

Finally - a trail SOP gave me my velocity for motion blur and a point sop with a min expression allowed me to clamp my velocity and thus motion blur to a threshold The attribute create SOP gave me width so my lines could be rendered as curves.

The final result which also used some real footage of electrical arcs.

Prido Effects project

2010-06-09T02:26:00.000-07:00

Character modeling,texture /displacement Maps and animation :
Mike Paech
motionjunkie@gmail.com

displacement 1 and below no displacement

ok!

Nov 12 update !

I'm back on this project !

The overall goal is to review render passes in Houdini and some FX by lighting Prido - the character in two environments - a stormy night and a dry dusty day. FX included will be rain, rain bouncing off of the character, splashing water, drips off of the character, some breath and some lightning. For the Dry env, there will be dust and heat distortion.

Currently ive rebuilt the scene for H11 Apprentice and have had some wierd rendering. ive noticed the shader work flow has changed a little so - this will be the first thing i get sorted.

fbx rigs from maya

2010-06-04T16:27:00.000-07:00

this is why caching your animated geometry is good ! :P

the end of a small era...

2010-06-01T23:42:00.000-07:00

...on this Friday, I will say goodbye to Cutting Edge Post

I really enjoyed working with these people and was lucky enough to learn a whole bunch of Houdini from the 3D dept. !

I worked on some great projects including the Aussie hit feature Beneath Hill 60, and the soon to come aussie horror "Needle", working alongside other talented artists such as Dave Brown, Tom King, Kate Kerrigan , Andrew Kimberly, Ant, GoatBoy, Swinney as well as VFX supes Ron Roberts and Steve Anderson.

I also had the pleasure of working with one of the loveliest producers I had ever met - Jo Gregory.

Thanx for the good times guys !

Voronoi shatter ReadMe

2010-05-12T06:33:00.000-07:00

Voronoi Fracture OTL

This OTL contains a Voronoi Fracture SOP,
as well as Fracture Solver and Fracture Pieces DOPs that does dynamic, impact location-based fracturing,
and a few other helper assets that provide base functionality for these assets.

Assets overview

Voronoi Fracture - SOP - provides Voronoi fracturing capability
Reattach Pieces - SOP asset that iteratively, randomly fuses groups of geometry as output from the Fracture SOP or the Shatter SOP
Fracture Solver - DOP - create fractured geometry for RBD objects within a DOPnet based on impacts Fracture Pieces - DOP - responsible for creating new objects in the DOPnet from the fractured geometry Nearest Points - SOP - support Vex SOP that uses point clouds or neigbour information to put the N nearest points into an attribute on each point

If you're unfamiliar with what a 2D Voronoi diagram looks like, google "Voronoi Diagram" and you should get plenty of examples. Or look at the "basic_2d" examples in the example fracture file.

Voronoi Fracture SOP Overview

The Voronoi fracture SOP takes two inputs: the mesh to fracture, and the points around which to build each Voronoi cell. Typically these points will be generated by one of two SOPs, the Scatter SOP, or the PointsFromVolume SOP.

If doing a solid fracture, where the interior surface of the object is built for each piece, it is very useful to have all the points reside within the volume. That will ensure you'll get one piece/fragment for each cell point. Both PointsFromVolume and an IsoOffset to a FogVolume followed by a Scatter SOP will do that. PointsFromVolume is useful if you know the approximate size of the pieces you want, since it operates on point separation. Scatter is useful if you know the total number of pieces you want.

It's also useful for location-based fracturing, as you can modulate the density from the IsoOffset SOP to generate more points within particular regions of the object.

Where there is higher point density, the Fracture SOP will generate more, smaller pieces.

The provided .hip files have examples of both types of point generation, as well as location-based fracture. At the moment the Fracture SOP takes a very brute-force approach to building the Voronoi cells.

For each input cell point, it incrementally clips the input mesh by the half-plane that divides the current cell point and another cell point. If building the input surface, it caps the resulting hole in the mesh, then continues iteratively clipping and capping.

This sounds pretty slow, and it is, but two things save it: the Clip SOP is quite fast, especially when it can trivially reject the input geometry (i.e. it won't clip anything), and the Fracture SOP uses pointclouds to start with the closest point and works outwards, short-circuiting any additional work when the Clip SOP won't have any effect, and stopping at the user-defineable "MaxCuts" parameter. Currently the Fracture SOP also detects then when the input cell points are co-planar, and uses the Triangulate2D SOP to get the adjacent Voronoi cells. So for most 2D inputs you should not see any artifacts.

Most of this is demonstrated in the example files, but a couple of tips when fracturing:

--Mesh complexity slows down fracturing more than anything. PolyReduce before fracturing if you can.
--The Fracture SOP should support most types of geometry, convex or concave. If you end up with artifacts and are sure the MaxCuts value is high enough, please let me know on the odForce forum.

--When testing fractures, debugging the MaxCuts value, etc, turning off "Create Inside Surface" will speed things up and should look the same on the surface of the object.

--The sign of a too low MaxCuts paramater is overlapping polygons on the surface. Sometimes you can template the initial geometry, put the Display flag on the points, turn on point display and point numbers, and determine which cell point is causing the problem. Enter that number into the "Cell Point Group" of the Fracture SOP and you can quickly test increasing the MaxCuts param until the artifact goes away.
There's an example of too low Maxcuts in the example file.

--Sometimes you'll have problems with insufficent point density in long appendages or something in the input object. Try using IsoOffset and scaling the density up in those areas. See the "horse" example in the example files.

--Don't use "Convex Interior Polygons" to triangulate the interior surface. If you want that, apply a Divide SOP after the fact with "inside" as the group.

Dynamic Fracturing Overview
The dynamic fracturing functionality in this asset is provided by the combination of the Fracture Solver DOP and the

Fracture Pieces DOP.
The Fracture Solver DOP is responsible for creating fractured geometry for any object that needs to fracture on a given timestep (usually due to impact or Magnet Force explosion). The Fractured Pieces DOP checks for new fractured geo at every timestep, copies the appropriate whole object enough times to create each new piece, assigns the new geometry to these new pieces, and deletes the original whole object. On most timesteps where there are no impacts, neither DOP does anything.Fracturing usually occurs as the result of an impact. The basic algorithm for location-based fracturing as performed by the Fracture Solver is demonstrated in the basic_fracture_examples.hip file under the "location-based_fracture" subnet.

Dynamic Fracturing tips(a few of which apply to the Shatter SOP as well):

--If pre-fracturing and using RBD Fractured Object or Glue Object, make sure to set group mask to piece_* or equivalent, else you'll also get an RBD object for inside and outside group, which will mess things up.

--It seems that changing settings inside a SOP solver won't always cause the DOPNet to recook. Since most of the parameters on the Fracture Solver go straight thru to the SOP Solver, often you have to do force a recook of the DOPNet when changing params (I often bypass and un-bypass the Multisolver DOP)

--If you're not sure whether an object will fracture or not, try it on its own in the SOPs context first with the Voronoi Fracture SOP.

--Use "Visualize Impact Region" to get an idea of where the Fracture Solver thinks the impacts are.

--If you set up a sim from the shelf and have "Ghost Objects" on in the Viewport, Houdini doesn't seem to display most of the new pieces. Turn off "Ghost Objects" when in DOPs (not a bad idea anyway).

--Even when the sim is done caching, there can be a slight hiccup in the playback when lots of new pieces become visible. Flipbook to get a better feel for the smoothness of the whole/fractured transition.

--The fracturing operation necessarily occurs after the RBD Solver has already handled the collision, so sometimes the whole/fractured transition looks clunky. Usually substepping the entire DOPnet makes things look/behave a lot better. Two is often sufficient; I often use four.

--The pieces created by the Fracture operation tend to have many sided polygons.

To avoid interpenetration you might have to toggle the collision Surface rep to Edges and toggle on Triangulate (slow). This is mostly true for stacked up pieces. Explosions and shattering and such where the pieces go everywhere it's not usually necessary.

--Use as coarse a collision Volume resolution as you can get away with.
Calculating the SDF for hundreds of pieces can take a long time and is often overkill. I may add automatic scaling of the resolution, but for now there's an example that shows how to override the resolution on just the pieces.

--RBDAutoFreeze with a relatively high "Enable threshold" is your friend.

--To temporarily turn off fracturing, just bypass the Fracture Solver.

--To avoid fracturing a particular object, set the "Group" field of the Fracture Solver to exclude that object (method may change)

--If you only want one level of fracturing, set the Min Volume to just under the volume (mass/density) of your object, or put "rdbobject1", not "rbdobject1_*" in the group field of the FractureSolver, which will exclude any pieces from further fracturing.

--If you know your geometry will fracture correctly with a high enough MaxCuts value, and you're using less than 100 or so pieces per fracture operation, it might be worth it to set the MaxCuts param of the Fracure Settings to the max number of pieces for the fracture.

Sometimes it's better than having to resim the entire thing because of bad geometry from the fracture operation.

Parameter Reference
Voronoi Fracture SOP
Group to Fracture - Primitive group to fracture
Create Inside Surface - Whether to build interior surface while fracturing
Connect Inside Edges - like Shatter SOP, connects surface polys to interior polys, usually off.
Cusp Interior Edges - just applies a Facet Sop to the "inside" group with Cusp Polygons at 40 degress
Visualize Pieces - colors primitives by piece number (should this be points?)
Piece Group Prefix - the name to prefix all piece group names with Cut Settings
Cell Point Group - a pattern/group expression that specifies a subset of points around which to cut cells
Max Cuts Per Cell - number of other cell points that will be considered when cutting a given cell
Cut Plane Offset - offsets the cutting plane by this amount to put some space between the pieces
Convex Interior Polygons - convexes the polygons generated in the interior at each step
Max Interior Edges - the number of edges a convex Polygon can have when previous option is selected

Reattach Settings
        Reattach Piece - whether to reattach pieces or not
        Iterations - number of reattach iterations
        Seed - a random seed used in picking which pieces to fuse
        Point Tolerance - the tolerance used in the Fuse operation when reattaching pieces

Delete Faces at Reattachment -
attempt to remove coincident polygons when reattaching Voronoi cells

Limit by Face Area Ratio - not yet implemented
Limit by Total Face Area - won't reattach if total surface area of combined piece would exceed this value

Fracture Solver DOP
Impact Settings
Minimum Impact - an impact has to exceed this value to cause a fracture
Minimum Volume - an object has to be larger than this (mass/density) to be eligible for fracture
Re-fracture Delay - a piece must have existed for this many seconds before it can fracture again
Compute Number of Points - have Scatter automatically calculate number of points in impact volume (bit flaky)

Number of Points - min and max number of pieces that will be generated by fracture

Points per Area - used by Compute Number of Points
Location-Based Fracture - fracture based on impact location
Fracture From Magnet Force Metaballs - add the metaball geometry for any Magnet Forces to an object's impact zone

Impact Radius - the radius of each impact for location-based fracturing
Outside Radius Percentage - the point density outside the impact radius
Visualize Impact Region - visualize impact region with red/white ramp
Fracture Settings same as Voronoi Fracture SOP above

Velocity Transfer Settings
Velocity Scale - overall scale for velocity transferred to new pieces
Randomness Scale - overall scale for random velocity added to new piecesPre/Post Velocity scale - blend of pre-post impact velocity to transfer to the new pieces
Group - group of RBD Objects the Fracture Solver should solve for Fracture Pieces DOP
New Pieces Group - name of group that new pieces created by this DOP should be put in (for creation timestep only)
Group - group of RBD Objects this DOP should create new pieces for

animated noisy gradient in Houdini

2010-04-02T21:24:00.000-07:00

what is a trivial task...in Max, is a bit wierd in Houdini...but not so bad when you see how.

Once this is set up - you can always save this as an asset as well.

I started plaing with the old ramps VOP, and then realised the new ramp generator is

the quickest and easiest way - that I know of.

1. make sure you have a shader view ( like the Material Editor...sort of...) window open,

otherwise youll have to make a grid with UVs......im busy thesedays :)

2. make a vopsop surface shader ( and apply it to you geo if you have some)

3. dive into it and add a ...well add these !

click the image to see it bigger

what the hell ! :)

I have to make all these nodes just for this effect !

umm yep ! Houdini excells at complicated tasks...so simple talks are a little more complicated.

some shortcuts...

the globals is given to you for free in a VOPSOP.

you could add your own paramaters called s and t - if the names are correct - Houdini recognises them and they work as if the were piped directly from the Globals.

the three parm's piping into the Turb Noise - i dont have to create and name them manually of course.

I just MMB on the parm's inputs that i want the user to be able to access on the top level and go with the default names - so the these are quick and easy no brainers.

The rest i have to click a few buttons for as you would in Max :)

the key is the ramp parm - it could be a float (spline) ramp or a vectory ramp - i went for simplicity.

The other tricky thing i found - was to plug s and t (like U and V) into my noise - i couldnt see the noise without giving it s and t.

So the s plugging into the ramp gives me horizontal ramp - t would give me vertical. This is mutiplied by the noise, and piped into a simple mix - note the dotted line here indicates values are being converted - the multiply is outputting a vector - but the mix wants a float as the Bias - so Houdini automatically converts it to read a float.

The animation of the wipe from left to right is done by animating the position from 0 to 1 in the top level of the VOP shaders - in the ramps parameters. Ive animated the position on two points on the ramp.

Another more WYSIWYG way - would be to do this in COPS - houdinis compositor - this would be similar the the gradients in Photoshop or After Effects - but this would likely require 'rendering' out an image sequence to disk - just like the old days !

some other things i thought you can play with:

* using an expression in the point positions to keep them evenly spaced, and to enable only having to animate one - the other is driven by the first eg point 2 pos = point 1 pos + 10%

* mixing several types of noise together

*animating the noise / size of the noise

umm im sure there are more ways - and probably more efficient ways to do this in VOPS, this is what first came to mind.

have fun !

inspirational links

2010-03-24T02:31:00.000-07:00

ive decided to start posting some inspirational links
....some of the stuff out there blows my mind !

Ian Worrel and Co. - wow !

Timelapse snails

incredible pencil sculptures

Petri Dish Art !

Love and Theft

Octopodi

PBR test 2

2010-03-23T18:46:00.000-07:00

and the seond images is the same but with a colour limit applied - and then equalised by the preview in the 'IPR' / renderview - which takes the gamma right down to .172 something...something....

note the self illuminted tube isnt darkened - the image is / was linear from Houdini.

SOPS MoBlur play

2010-03-21T04:05:00.000-07:00

VOP COPS play

2010-03-20T20:27:00.000-07:00

matching the plate

2010-03-17T21:03:00.000-07:00

instead of doing what i used to do and line up geo
in the viewport - albeit a big one, with a bg image plate...

now i make my objects render with a wireframe
shader, and zoom in on the region i need to match
and render only that little area.

With a wire frame shader - on the geometry it becomes really
quick - almost intereactive - so in one view i can edit or transform my geometry and in the other i can see the wireframe render update over the plate and i can get a much better match.

* rendering at 2048x1172 gives you much clearer idea if your geo is accurate anough - but theres no point if your rndering at less res than your screen res - you may as well just line it up in the viewport ! :)

...kinda reminds me of using max's virtual viewport. :)

you can do a virtual viewport in Houdini as well...a post for another day.

copy stamp play

2010-03-16T14:53:00.000-07:00

experimenting with new techniques and re-appropriating methods is too much fun !.
this is simply some static scattered
cubes with a motion blur attribute randomly stamped on them.

less cubes, less motion blur

copy stamp play

2010-03-16T01:29:00.001-07:00

this random play reminds me of the old days at Famous Faces,

messing around with Vicon cameras :)

its all in scale here :)

2010-03-16T00:26:00.001-07:00

http://www.newgrounds.com/portal/view/525347

2010-03-16T00:02:00.000-07:00

regarding the maya to houdini pipeline:

animation is brought in via the fbx format
(NB in the fbx import options check `unlock vertex cache`
otherwise all the animation will be saved in the Houdini file resulting in very large hip files rather than referenced on disk like it should be)
also check 'import directly to /obj' to bring the nodes directly into the root level of houdini thus bypassing a useless encapsulating layer of hierarchy
so far we have been starting a new blank session of Houdini to import the fbx files
and then copying and pasting the relevant nodes made by this fbx import into ANOTHER houdini session which is setup for Houdini specific geometry caching and rendering.
the models come into Houdini automatically with a vertex cache SOP that links the model with its associated animation CHOP (channel operator) to give it the life that puts bread on out tables.
By default the path to the animation involves the object name in it
(in the choppath parameter)
such as :
../../fbx_chops/MDL_tongue02_chopfile

the fbx import process automatically adds "_chopfile" to the end of the name
after sourcing the object name (tongue02) in this case which makes our live kinda esier once we get our heads around whats happening
we can then replace this path with this :
`"../../fbx_chops/" + opname("..") + "_chopfile"`
we've split up the string adding quotes and + signs to concatenate it .
the cmd 'opname' looks at the objects name in question procedurally and automagically
derives it - no matter which object we are dealing with.
".." is like 'the node, one level up from where we are now' - just like unix.

the single quotes around the expression force it to evaluate.
this new expression can then pasted onto ALL the vertex cache SOPS in every animated object - and pasted all in one hit using the attribute spreadsheet.
when the animation in Maya is updated or changed, we simply copy in the CHOP network *ONLY* and as long as no object names have changed in maya - we can link the new animation from maya to the old models in Houdini (essentially the same models - because they cant change point count). The Chop netwotk name shouldnt change either - but if it does - we just change our expression to suit.
why cant we just past in the new animation network and all the paths will automatically connect as they are ? well we could....but if there is any old fbx animation networks hanging around in houdini, it will add a '_1' increment to the name and break the path.
why cant we just remove the "_1" from the name of the animation network ?
we could but any paths that are specific - or explicit or not using an expression
will automatically update to follow the current fbx animation it is connected to, in an attempt to keep the paths connected.
So if we ever have 2 or more fbx animation networks in the one houdini file - it can easily be broken. This is avoided with the expression meaning we only have one name to keep an eye on one name - the fbx CHOP subnet name.
this gives us a workflow to simply update animation from maya by coping and pasting one node from one Houdini file to another and hopefully everys at the pub by 6 pm with a beer in there hand and smiles on there faces :)
----------------------------------------------
we could also just go into the fbx animation node and simply copy all the CHOP nodes, then paste them into the old fbx_chops subnet node (*after* deleting all the old ones to avoid houdini's automatic renaming) which is even easier !

some opscript

2010-03-01T14:31:00.000-08:00

from odforce...

mental note to self:

"You can always run

opscript -r -b /obj/*

that will show you all the commands needed to reproduce the object networks in a script format.."

DOF entry updated

2010-02-28T14:46:00.000-08:00

post :
new entry

BRDF spectral DATA link

2010-02-17T19:09:00.001-08:00

ftp://ftp.eos.ncsu.edu/pub/eos/pub/spectra/

RENDERING DEPTH MAP SHADOWS

2010-02-14T21:11:00.000-08:00

rendering shadow maps outto disk to speed up your final renders

even after the rat shadow maps are baked to disk,
you can still change a number of parameters with having to write the shadow maps back to disk again

ie

colour
intensity
shadow intensity

shadow quality - im not sure about this one

shadow softness and shadow blur

NOTE INCREASING PIXEL SAMPLES AND RES IS VERY ADVERSE TO RENDER TIMES !

it may be better to increase pixel samples to get mor detail than to increase resolution fo the maps.
it seems double the map size and double the samples will more than quadruple the render times.

i should do some proper tests...

IOR's for everyone !

2010-02-04T22:23:00.000-08:00

http://forums.cgsociety.org/archive/index.php/t-513458.html

vol disp shader

2010-02-02T15:57:00.001-08:00

wonderful world of stere-ereo

2010-02-02T02:29:00.000-08:00

well its not pretty - but here it is - my first stereo image...

youll need red and blue glasses !

some stereo volumes from the viewport:

and some notes from the web:

Notes from wikipedia

basics:
anaglyph images are used to provide a stereoscopic effect.

2 colour glasses - each colour chromatically opposite
each colour blocks out the opposing light waves leaving near black

each image is superimposed (additively) but offset with respect to each other to produce the 3D effect
ususally the subject is in the middle with the forground and background shifted latterally in opposite directions

~the visual cortex of the brain fuses this into perception of a 3D scene or composition

most glasses are red on the left eye and cyan on the right
red and blue is cheaper - but there is a improvement in image
especially when viewing skin tones with a cyan filter

anaglyphs are easier to view than parallel (diverging) images or cross viewd pairs stereograms (magic eye ? )

Anaglyphs can be made in two ways
1 using two cameras offset from each other and convering - aiming toward the same subject
with different filters on each camera

2 on a computer by using pixel operations instead of the filetrs to knock out each color - and the offset can also be done digitally

** NB you stil need two base images when creating anaglyphs digitally

in photoshop - you can adjust the colours for the images and screen them back onto each other

TERMS

IAD Inter Axial Distance / IOD inter-occular Distance
can we assume inter occualar refers to eyes interaxial refers to camera lenses.
http://forums.creativecow.net/thread/268/43#51

IPD - inter-pupillary distance
is considered the correct term for the measurement of the distance between the left and right eyes of the viewer.

IOA inter axial Angle - this refers to convergence - the angle the cameras are pointing in
toward the subject - also called `toeing` in

Parallax (wikipedia) fro greek parallaxis - "alteration"

In the art of stereoscopy, screen parallax is defined as a measure of the distance between
left and right corresponding or homologous image points when such points are projected
on a screen.

homologous from greek 'to agree'
biology : similarities between charateristics of organisms eg forelimbs in mammals

wikipedia:

Parallax is an apparent displacement or difference in the apparent position
of an object viewed along two different lines of sight.

It is measured by the angle of inclination between the two lines of sight.

Nearby objects have more parallax than distant objects - therefore you can measure distances
Stellar parallax provides the basis for all distant measurements in astronomy.

Stereopsis:

Many animals, including humans, have two eyes with overlapping visual fields to
use parallax to gain depth perception; this process is known as stereopsis.
Lenticular is the adjective relating to lens.

AutoStereo - general term to descripe the stereo effct from a device that does not require glasses
(either anaglyphic or lenticular)

-------------------------------------------------------------------------------------
Houdini Notes
-------------------------------------------------------------------------------------

Houdini has an asset which is a built-in stereo cam rig with controls for IAD
and ZPS - Zero Parallax Setting - which controls the convergence point.

in mplay the left image scan be viewed as C and the right can be viewed as C2

IAD - the distance between the two cameras - the center of the lenses ?
ZPS - Zero parallax screen - houdini make a plane where points of the
two images intersect

*    The ZPS coincides with the viewing screen
*    Objects between the camera and the zps,
   or in front of the ZP appear to be in front of the screen
*   Objects behind the ZPS in 3D, appear to be behind the screen

* when there is no IOA (angle) - ie the cameras are parallel - the
convergence plane appears to be just 'beyond infinity' - or as far as the eyes can see.

* there doesnt seem to be a control for IOA on the Houdini StereoCamera
- the cameras are paralell

-------------------------------------------------------------------------------------

* "...the big caveat with toe in, is it creates geometric distortions
due to symmetric keystoning. "

http://forums.creativecow.net/thread/268/134
-------------------------------------------------------------------------------------------------

Algoythmic Interaxial Seperation Reduction
(to produce lower parallax values)

http://www.freshpatents.com/Algorithmic-interaxial-reduction-dt20080228ptan20080049100.php

In the art of stereoscopy, screen parallax is defined as a measure of the distance between
left and right corresponding or homologous image points when such points are projected
on a screen.

homologous from greek 'to agree'
biology : similarities between charateristics of organisms eg forelimbs in mammals
-------------------------------------------------------------------------------------------------

LINKS

Professional Anaglyph camera rigs
http://www.3dfilmfactory.com/3d_camera_rigs.html

French dude worked on meet the robinsons
makes his own anaglyphs and camera rigs
http://bernard.mendiburu.free.fr/pro/book/movies/

Avatar

Imax Cineams
http://www.imax.com/

Wikipedia : Lenticular Lenses
http://en.wikipedia.org/wiki/Lenticular_lens/

Lenticular Prints
http://www.gorillaprint.com.au/index.php?/print/lenticulars.html

D A Y B R E A K E R S

2010-02-01T13:26:00.000-08:00

woohoo !

my first feature film experience as an FX animator.

Big Kudos to the Team at Kanuka Studios !

trailer

Rangi Sutton - FX Supervisor
Kirsty Martin - FX coordinator
"Robert James Kelly" - Houdini TD
Allan Mckay - TD
DJ Nicke - Char Animator
Alicia Aguilera - Compositor
Loren Robinson - Compositor

for a full listing of credits:
http://www.imdb.com/title/tt0433362/fullcredits

some reviews:
http://www.imdb.com/title/tt0433362/

as i get time, ill try to write about the experience and the effects i worked on.

go see it at a cinema near you !

old chrommatic abberation post updated

2010-01-25T23:48:00.000-08:00

missing motion blur ? borrow some V !

2010-01-21T23:54:00.000-08:00

from gmail chat:
i did a nifty trick today ! (thanx Dave !)

...well nifty for me...

one of my frames for some reason had no motion blur

so on the previous frame and the frame after

i locked copies of the nodes.

Then took the velocity (v) off those - averaged them in a VOPSOP and which also applied the new v to the frame with the missing v.

then a switch SOP to switch between the old node and the fixed node for just that frame !

i feel like the attribute nodes are finally less abstract for me

i think i just needed a practical example of usage to feel comfortable with it

in the image - you can see 2 different ways of achieving this - the first method i used - on th e left is more kunky - more nodes - but it works. The second - the almighty VOPSOP is so elegant !

inside the VOPSOPS are 3 new nodes !

COPS bugs

2010-01-21T15:35:00.000-08:00

I know theres a few bug in COPS - but heres one i hadnt seen before

converting from 16 bit tif to 8 bit in a ROP - i got some really funky output.
soon solved however with a conevrt COP before the ROP

more smokin pt II !

2010-01-11T20:56:00.000-08:00

displacement problems

2010-01-07T22:26:00.000-08:00

displacement problems

more smokin !

2009-12-17T22:46:00.001-08:00

complement displace (along normal affecting only P, not N)
scale -.5
amp 1
defualt shader noise on
complement displace (along normal affecting only P, not N)
scale -.5
amp 1
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale -.5
amp 2
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale .5 - displacing the wrong way ?
amp 2
defualt shader noise off
displace (along normal affecting only P, not N)
scale 1
amp 2
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale 1
amp 2
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale 2
amp 1
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale -2
amp 1
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale1
amp 1
defualt shader noise off
complement displace (along normal affecting only P, not N)
scale -1
amp 1
defualt shader noise off
displace (along normal affecting only P, not N)
scale 1
amp 1
defualt shader noise off
displace (along normal affecting only P, not N)
scale 1
amp 1
defualt shader noise on

no displacement
defualt shader noise on
no displacement,
no noise,
only vorticle action

pyro defaults:
you can see a bit of grey smoke forming from combustion over top of the fire
no scattering here
some lights instanced onto points in the fluid would be cool :)

plasma

2009-12-13T16:41:00.000-08:00

At Cutting Edge, I worked with TD Robert East - http://tenmenmarching.com
and VFX superman Steve Anderson, and producer Jo Gregory, to create
some 'plasma - in a belljar' type visuals for an anti-smoking ad.

I used some post processing on my renders to help the Flame operator
compile the layers into the finished product.

Our plasma was then driven by audio files to give the illusion that the plasma was energized by the voice of the actor.

smoke / cloud

2009-11-11T13:00:00.000-08:00

PBR test

2009-10-10T19:41:00.000-07:00

3x3 pixel samples
standard glass shader
PBR render,
VEX GI_light with 32 samples
13m45s on a dinosaur computer

6x6 pixel samples

Rangi Sutton's test scene

point instancing !

2009-09-27T00:24:00.000-07:00

a little play with point instancing inspired by the Duracell advert - here
http://www.postdreamer.com/video/602_duracell

working in Melbourne

2009-05-24T03:08:00.000-07:00

well we cant use Houdini ALL the time....shame...but im having a long awaited excursion in Maya now.

lots of information to come....if only i had time.

future topics could include:

fur/fur card generation in Houdini and transfer to Maya for rendering

with the new service pack from Maya, we can import vertex colours through FBX
in Houdini - the normals on the fur can be blended into the normals on the skin for better fur to skin blending
LODs on fur cards

grease and Mud with nParticles in Maya and Houdini
poly + voxel Dust in Houdini and Maya

rendering with nParticles from Maya Unlimited- on Maya Complete !

Mel script and equivalents in Houdini

in this production i learnt a bit about Mel from Pawell Grochola (Dneg)
, Joe Leveson (FrameStore / RSP / Fuel) and Jess Curtis (Fuel)

we used scripts for :

generating Lighting passes, and rendering FUR geometry
importing and exporting scene assets / general scene mangaement
importing obj sequences and animating the visibility like stop-mo

soon....

Houdini Fluid test

2009-02-11T04:49:00.000-08:00

early days...stuff i can improve on right away:
a reflection / environment map.

more resolution in the mesh / smaller fluid particles.

nicer render- ie a cyclorama - i have an asset for this !
shadows - a wet map. This could be created manually from a top down render
or there must be some procedural method - proximity between the fluid mesh and the
collision plane maybe affecting point colour...like an Amb Occlusion pass ! :)

to far too long to render on my old, old machine :)

Maya nParticles Tests

2009-02-09T02:12:00.000-08:00

2nd nParticle anim in maya
with cache sped up 10 times.

fisrt nParticle anim in maya

Maya PLE ncloth tests

2009-02-02T14:27:00.000-08:00

well it has been a REALLY long time since i played around in Maya,
what ami doing in Maya anyway ?! I have to do some comparisons.
Im also keen t investigate Maya and Houdini translation techniques.

4th test

tshirt

3rd ncloth test
sphere pulls the cloth around via a
constraint and collides with it

2nd n-cloth test, the torus has 2 'point constraints' on it
as well as a collision relationship with the cube and a noise field
turned on in the n-cloth solver.

1st test - one point constraint and a noise field in the solver

Fluids Tests

2009-01-28T18:57:00.000-08:00

HAIR TESTS

2009-01-28T04:52:00.001-08:00

much newer and nicer hair / fur renders in 2011 !

http://houdiniadventures.blogspot.com/2011/06/fur-renders.html

sidefx - ICE ! :D part 2

2009-01-12T07:30:00.000-08:00

The tricky thing about this, is its all procedurally built from a line.
A spline goes in - and this comes out ! Rendered out with takes and comped in COPS.

sidefx - ICE ! :D part 1

2009-01-11T19:46:00.000-08:00

next ill break it up into passes and try and push the look.....

random lines

2009-01-02T01:24:00.000-08:00

This was an interesting little bit of play :)

I started with a sphere, randomised the points - then with a point SOP,
lay a line over the points using the second channel - essentially shifting the line's points to those of the sphere. Then i converted it to nurbs and back to polys to smooth it out, and then added a few effects in COPS - voila !

Assemble

2008-12-20T05:25:00.000-08:00

Assemble HDA

new to 9.5 is the assemble HDA.
I first stumbled on this when i used a shelf tool to make a RBD Glue object. The Assemble HDA was automatically added just like the Auto Dopnet is added.

From the help file, Assemble is used in conjunction with Break and Shatter. Gone are the days of manually cutting up your model it seems ! The Break SOP already has bundled in it a fractalised grid or box or sphere - your choice, and boolean / Cookie operations that break the model up into seperate pieces for you !

Shatter goes one step further and allows multiple breaks by uisinfg the foreach SOP to re-iterate breaks over your object. I chose 10 breaks - and it bogged down quite a bit.

Once you have a bunch of 'shards' or pieces, you generally want to group these into their own groups with a common group prefix name, allowing you to use RBD fracture or RBD Glue DOPS to complete the sim.

This is where Assemble comes in. (Shatter already has an Assemble HDA bundled in it).

Assemble essentially uses a connectivity SOP and a partition
SOP to group all the pieces and give them a common prefix to the group names. It also has some options for edge cusping and faceting.

If the broken object is made Dynamic - Assemble is added automatically - as it did for me.

hers some more links:

http://forums.odforce.net/index.php?showtopic=8143
a shatter script for maya

pompom test

2008-11-30T22:42:00.000-08:00

my intial test for some cheerleaders pom poms

to make this i used wire dynamics, and fleshed it out with a trail sop.
my next version will have only 3 colours created with groups and wire to wire collisions and wire to handle collisions.

copy stamp play

2008-11-19T02:59:00.000-08:00

Remove Lonely Verts

2008-11-18T23:11:00.000-08:00

this entry contains a little bit of VOP-SOP fun as well as outlining the
process of making a digital asset in Houdini.

my friend Rob Kelly initially nutted this out - then i found that i needed
it, so i set about making one for myself which turned out to be easier than i thought.

my first attept was in H8 and i remember getting frustrated with for loops not working as i expected - but now with H9's Vop Sop - a truly versatile SOP. {i have since removed my sheep joke from this entry :D }

the main application for finding lonely verts ( verts that have less than 3 neighbors )
is to delete them so they dont interupt the subdivision process
Lonlely verts are often left behind in the modeling process - whenever several connecting edges are dissolved.

I added a VOP SOP - then after mucking around with the for each VOP - i realised every op in the VOP SOP was going to be applied to every point in the incoming geometry anyway - so i didnt need a for loop at all.

in the VOP SOP i simply have the point number from the global parameters (fom the incoming geometry) going into a neighbor sop - which counts how many neighboring points the current point has - and then decides if it should be coloured or not.

The trick here is to get the neighbor count to either zero or one which will act like a switch.
i noticed that a lonely vert has only 2 edges coming out of it - where as a 'healthy' vert has usually four - or three depending where it is on the model. There are exceptions however ! ie - the corners of a grid also only have two neighbors !

The only way ive though of so far to deal with these is to explicity ignore them by putting them into a group, before the asset does its job. We can streamline this process a little by some sort of edge detection or at the very least providing a field with the group name to ignore, as part of the asset.

The coloured points are grouped by their colour and the option is there in the asset to delete them or not. Having a toggle is a good way to see what the bleep is happening.

Mercedes Benz Video !

2008-11-05T04:43:00.000-08:00

Mercedes video obtained !!!

monthly research : IFD files

2008-11-01T06:01:00.000-07:00

the IFD (Image File Descriptor ?) files in Houdini / mantra are the equivalent of the RIB files for Renderman -
they are a description of the 3D scene for that frame.

from the help files:
ifd is the file format produced by houdini..and consumed by mantra.
The IFD file contains a complete description of the scene and how to render it.

you can render an image directly from an ifd file in the shell without opening houdini simply type:

mantra < [the name of the ifd file]

I wonder what an ifd looks like if i open it ?

heres one i made from houdini:

IFD created by Houdini Version: 9.5.255
# Generation Time: Nov 05, 2008 at 14:14:24
# Render Defs: /lv0/opt/hfs9.5.255_linux_x86_64/houdini/soho/IFDmantra9.5.py
# HIP File: /lv0/tbe/shots/6_4/hip/6_4_ink_wire_tweak_v08_t02_dp.hip, $T=16.44, $FPS$

# Output driver: /out/ink_wire_BG1
ray_version VEX9.5.255
setenv HIP = "/lv0/tbe/shots/6_4/hip"
ray_property object velocityscale 0.02
# Retained geometry
# SOP /obj/rs_holdout_map1/geo1/RENDER
# Save geometry for /obj/rs_holdout_map1/geo1/RENDER at time 16.44
ray_start geo # {

ray_detail /obj/rs_holdout_map1/geo1/RENDER stdin

BgeoV^@^@^@^E

...and the rest is garbled by my text editor - pico.

soft body test with particles

2008-10-10T20:17:00.000-07:00

this was surprisingly easy wih the shelf tools !

I also used pops to emit a few particles where the softy collided.

Copy Stamp Play

2008-09-02T18:28:00.000-07:00

some copy stamping.

the scale and rotation (mostly in Y) is randomized based on $PT.
I used the fit01 expression to fit my random values into a desirable range.

in the first pic, the cards are just planes, but in the second, the cards are 3D with a slight bevel, and some noise (offset for each card through stamping)

to get the Houdini logo - i made sure 'use Template Attributes was on.'
so the Cd att. (color) was copied from the grid (the template) to the cards.
In my shader - i told it to use a Cd parameter and wired this into the colour so the colour info was piped through to the shader as well.

In my current version - i decided to animate the swirl feature of the logo into appearance. In the top view i made a rough poly curve /line that matched the spiral using my grid (with the texture's colours transferred to its points)
as a template.

I then gave it white point colours and animated a sphere along it, then transferred the color to the cards. For the sphere to leave a permanent trail behind it I used a trail sop....thus the cards are animated to turn white.

One issue i had with this attribute transfer - was that because the sphere with the white points is animated - and the grid/ ground plane is of finite resolution - the distance from the spheres points and the grids points changes as the sphere moves around - giving a flickering effect on the white. - The attribute transfer's distance is constantly changing as the spheres points move closer to and further away from the points on the grid.

To get around this - Rob suggested using a group. This was n easy solution - the sphere with trails - intersects the points on the grid (or the points scattered on the grid) and adds them to the group. This group then controls which points have their point colours changed.

misc tests

2008-07-30T05:48:00.000-07:00

some old tests

weekly.....monthly research...

2008-06-24T04:34:00.000-07:00

a glance at nuke...

i had a bit of a play with Nuke this morning...so i though why not have another

look at it...

---------------

from wikipedia:

Nuke (the name deriving from 'new compositor')^[1] was originally developed by Bill Spitzak of Digital Domain for in-house use beginning in 1993. Nuke used the FLTK toolkit, which was developed in-house at Digital Domain and was subsequently released under the GNU LGPL in 1998.

In 2007, The Foundry, a London-based plug-in development house, took over development and marketing of Nuke from D2.^[7] The Foundry released Nuke 4.7 in June 2007,^[8] and Nuke 5 was released in early 2008, which replaced the interface with Qt and added Python scripting, and support for a stereoscopic workflow. Nuke supports use of The Foundry plug-ins via its support for the OpenFX standard.

--------------------------

some notes:

just like fusion, you can hit 1 to get a viewer to pop up to display the node your focussed on.....which means you can select any node and then hit one to pop up a

preview of your tree at that position.

I noticed the menu has an open recent option....with the hot keys Alt - Shift -1, 2,3 etc...

Alt-G go directly to a frame...cool !

Alt-I script info..

Search / - just like houdini and linux !

CTRL-D disconnect or remove input

Zoom:

CTRL and a number to zoom in

ALT- and a number to zoom out.

F for fit and + and - to zoom in and out.

ALT-MMB for interactive zoom

ALT-LMB for Pan

` toggle the viewer

SHIFT ~ curve editor

S settings - you can specify a proxy here as well as general project settings

Shift - S preferences...

------------------------------------

ok from here i decided to investigate based on common tools:

a more structured approach...

splines / curves

add a bezier node under the draw submenu of 'modifiers' or tools

or just press P

CTRL-ALT-click to draw....

it seems by default the spline is closed.

some thoughts / questions and answers about splines from working in Fusion , After FX and Shake:

P (shift-p) allows me to draw a path

can i easily hide them ? -
O for Overlay toggles all the viewer type overlaid controls

can i animate the number of CV's ? and how is this interpolated ?

would I really want to do this ? i noticed shake was kinda klunkyu in this area -
you had to plan ahead with your keyframes.

can i easily control a feathered falloff or soft edge of the spline ?
using control gives me a soft edge for the bezier - indicated by a dotted line

the dotted line seems to actually indicate the beginning of the fall-off - not the end.

The solid line indicates the end of the fall off - where the spline is not having any effect - the outer most extreme region of the spline.

in fact moving the dotted - inner line can actually move the outer line as well - as if they were linked. CTRL gives independent control.

like shake.

x or right clicking and choosing 'BREAK' on the point will break the bezier handles.

cusp (corner) and blur / unblur and smooth (relink bezier handles) is also avail from this RC menu.

the help button has quite a few tips:

there is a transform jack when a few points are selected

you can also select points by clicking on the line between the points

Can i easily animate the spline as a whole ?

(there appears to be a handle like in shake)

the actual function of splines and masking seems a bit different
you can have a bezier node function with no input - it can exist in it s own right
in order to get some results that were logical to me...
i had to :

to be continued....

ok so i had some difficulties getting used to the masking with Nuke.
finally i read some of the help files: :)

from the first tutorial script i see that adding a mask or bezier shape to an image
fills it with white by default - so by changing the colour to black and inverting the mask i was able to cut a section of the im age out and overlay it (over) on something else.
So if want to use a filtere to affect just a region of an image this is one way i could do it.
Im really after a more direct way - luch as in fusion where you apply the filter to an image (which applies it to the entire image) then you can plug a mask into an imput designed for accepting masks and the filster is constrained tot hat mask.
the same process is complete in three nodes rather than four..

mercedes glk website launched !

2008-06-16T06:35:00.000-07:00

Mercedes Job makes it to SideFX's REEL !!!

www.mercedes-glk.com

looks amazing...but be warned - it takes a while to come down
hats off in a big way to the talent at Realise and Kanuka Studios !

some fun !

2008-06-09T23:22:00.001-07:00

springy curves emitting some particles...

ICP, Isixpack, BIC (rangi sutton)

2008-06-01T03:23:00.000-07:00

ICP - convert images to rat format for better memory usage in Houdini.

after typing in a shell (in a houdini environment)
i get:

icp copies one image file to another, optionally performing simple
operations.

icp [options]

some options

-u output uncompressed if supported
-v turn on verbose
-f flip vertically
-F flip horizontally
-R flop image 90 degrees couter clock wise
-r scale to w x h res.
-s scale to a percent of the original
-c crop area in UV coords
-C crop area in pixels
-P include planes at the specified indices
-L load with cineon LUT
-O save with cineon lut
-N do not convert cineon from 10 bit log

isixpack takes 6 images and makes a reflection map in rat format.

type for help

% isixpack -

------------------------

from the help - there is 3 ways to convert images.
1. through COPS
2. converting in MPLAY
3. isixpack - mentioned above

AH HA !

what i was really after was the bic command (written by rangi Sutton)

the bic command converts images between formats.

Usage: bic -i  -o  [-e] image_file_names

Takes each of the image files specified with image_file_names and converts them
to image files of the format specified with the output_format. The files
specified with image_file_names should be image files of the type specified
with the -i input_format.

Valid file formats are:

pic jpg jpeg tga gif gif89 rgb sgi yuv pict pix cin tx rat exr

Input files should have these suffixes.  eg myrender.rgb
Requires a valid Sidefx Houdini License.

Written by Rangi Sutton on 20/3/97 for HM3d Graphics Systems

Ball o' Worms

2008-05-19T04:15:00.001-07:00

Trials and tribulations...

well..im working on a new ball of worms and theres been some interesting developments...

the worms...
i took the old geometry from max in obj format and decided i could improve in it in Houdini - the ends of the worms in max had some 'bogeys' due to bezier handles being present and the fact that i told max to create the geometry in the spline object itself.

in Houdini, i used partition and connectivity to create a group for each worm, then i deleted all the worms except one, then rebuilt the group with a copy SOP - an awesome technique first shown to me by one of David Gary's old video tuts - the particles flowing along the l-system.

this way - all operations applied to the one remaing worm can also be applied to the entire list of groups / of worms :)

i grouped a bunch of co-linear - in worm space :) - points by using group by range, and then made a new spline from this, then swept new worms after re-sampling the spline giving me much cleaner worms...the obj was much too high in res.

then i decided to add a ring slightly fatter around the middle - see the pic ? and this was done by extruding - which was not good for the UVs - likewise i capped the open ends of the polys - bad for proceduralism and UVs. There was also a UV errorof some sort ruining my renders.

so today i went about solving these issues and opened up a can of well.....worms :|

my proc method of selecting the ends had to be scrapped - i made groups for the first and last point of the splines the swept the worms - proc ok - but then after copying spheres to these points i wasnt really cleanly selecting points or prims for extrusions or capping.

the sweeping itself also had to be redone unfortunately - as did the UV mapping - but uncovered some interesting techniques. The UVs were made with Rob K's (meshsmooth) unfold curve SOP
which looks at the angle of segments on the curve and then applies that same angle as a rotation to the specific segments and thus straightens out the curve. With the same method used for the backbone curve - a sweep with give you a flat plane which can easily be mapped - these UVs can then be transferred to the same sweep (with curly cuves) thus mapping the worm.

I also decided to go to town with the image and add some rain and all the water FX that would go with it - rain splashing against the ball of dirt and trhe worms and causing mud, and water dripping off the worms and bouncing around on the set / cyclorama. Joy...more cans of worms !

more updates to follow soon.

some Renderman

2008-05-13T17:28:00.000-07:00

I can translate this to VEX later.
seems i need to know vi or something similar for efficient text editing.
at the moment i have Context which seems ok and has custom features for editing RIB files but not sure about VEX.

from "Renderman for beginners"
1.4 "How a renderer works"

3D scene description
|
object to world to camera transformation
|
clipping, culling, projection
|
raterisation,hidden surface elimination, shading
|
rendered image in frame buffer or stored on disk.

2.3 "How PRMan works" & Reyes algorithm

Rib file is parsed (scanned)
Primitives' bounds are checked to see if
they lie in the cameras frustrum ('vision') -
if not those 3primitives no longer need any calculations
|
primitives are checked to see if they are small enough for dicing
and if not - broken down or diced themselves into smaller chunks / sections
until they are small enough for the Reyes dicing
|
Reyes dicing into micropolygon grids
each primitive that is small enough is diced into a grid of micro-polygons
It is these micropolys that get shaded and eventually contribute to the
final pixel colors
|
shade at grid verts
|
bust the grid into individual micropolygons
|
each micropolygon is tested for bounds
incase a displacement shader has moved the position of the micropoly
|
each micropoly is then sampled at pre-determined sub-pixel locations
(There number of sub-pixel locations is set up as a control in the RIB file
or in the interface in the case of Mantra)
and a 'visible point list' is made with the Z depth values
|
the point list is then spatially blended and collapsed into a final pixel colour and opacity using filtering to weight between several samples for that pixel.
Some filtering algorithms you may have seen are:
Catmul-Rom
Linear
Blackmann
Hanning
etc
|
Finally - the array of pixels is sent to a display buffer or saved to disk.

ocean shader

2008-04-22T07:14:00.000-07:00

heres a crack at an ocean scene,
not happy with it yet...but its been interesting.

ill have to find a model to stick in the water...

i got a SSS pass in there but its hard to tell if it really working properly.

no white caps yet and no tru Zdepth yet - my dodgey ZDepth was made by using an edge detect on the alpha of the water essentially creating a horizon line then blurring this and adding it to itself for the desired effect.

this was used as a mask for desaturation and SSS as well as blur.

the spec is bloomed out as well...all comped in Houdini :)

edit: next time i might try and reduce the wave height in relation to zDepth to try and
fake the scale of the scene - like a perspective cheat...any ol' trick to reduce rendering times on my old box.

edit: looking at other peoples work - i realised
i can fake the distance with a flatten effect based on camera distance.

-----------------------
some more shader practice:
simple opacity
dont forget:
the RGB has to be multipled by the Alpha to get some black for the OPACITY.
in this example i had a 32 bit TGA - which i then broke into its RGB vector and a 4th float value (the alpha) with a convert VOP
(convert Vector4 to Vector)

an image with an alpha channel may need the 'premultiplied' treatment.
- this can be done in COPS.

weekly research: MIP mapping

2008-04-21T18:47:00.000-07:00

what is MIP ?

wikipedia has the answers

Mip maps (invented by Lance Williams in 1983)

... are pre-calculated, optimised collections of bitmaps that accompany a main texture, intending on increasing rendering spped and reducing artifacts.

MIP is an acronym, from the latin : multum in parvo, or "much in a small space"

If the full res map isnt required - the renderer will automatically switch to a lower res version, or interpolate between the full- res version and a lower res version - if tri-linear filtering is enabled.

see anistropic mip mapping.

capsule asset re-made

2008-04-21T07:45:00.000-07:00

the original capsule asset post (post #2 is updated with some pics)
and the asset was remade.

original capsule post

crab update !

2008-04-16T02:37:00.000-07:00

HOOOPLA !
a new render of the crab with rangi's HDRI shader
there'll be more renders as his face design will be changing...

some SSS...finally.

2008-04-15T05:52:00.000-07:00

ball ' o worms

2008-04-12T22:40:00.000-07:00

this was supposed to be for CGSphere - but the camera is slightly off....so i think ill do it again in Houdini ! :D

changing the colours and saturation in photoshop on the worms pass really helped with the realism. I would like to improve the realism of the dirt.

LINUX file permissions

2008-04-09T19:00:00.000-07:00

from www.linuxforums.org/security/file_permissions.html

r readable
w writable
x executable

u user
g group - ie Administrators
0 others - not a member of a group or the owner of the file
a all
- no permission

use ls -l to see file permissions

eg

ls -l myfile
-rwxr-x--- 1 george administrators 10 2006-03-09 21:31 myfile

so for george - the owner - the file is readable , writable and executable.
for other administrators - the file is only readable - not writable but still executable
other users cannot read, write or run this file.

changing permissions : chmod
if george wanted to give write permission tot he other administrators
he would type

chmod g+w myfile

see the url for details

tricks from the forums ! - thx to all Houdniks out there !

2008-04-09T01:27:00.000-07:00

To detect holes, in non-manifold geometry, you can use the Divide SOPs 'Removed shared Edges' Toggle.

If this returns no points or prims, than your geo is solid. Otherwise you have non-manifold geometry, (either has holes, or some flipped prims and what not)