rendering maya fluids with motion blur using particles part 1

rendering Fluids as dense Particle cloud is common practice. the Krakatoa plus for maya or 3dmax is based on this concept. even without this plugin, you render the particles as point in maya hardware render or as clouds in maya software renderer or mental ray. the advantance: fast render times and most important –> motion blur !

this how it the particles look like:

on the right side i switched to software clouds mode and used radiusPP over lifetime


just place the emitter over your fluids emitter

set up the particle shape and use mayafluids as flied:


growing emitter

once, i had to create a growing particle wave, eating up an environment. i’ve used softtransform node with option “keep visualization in geometry” to quick a quick and easy circular mask and used it on noise.

for emission of the particle i need just growing part (difference from frames to frame). i’ve just subtract the emitter geo from previs frame to get only the growing part.

AOV shading fun in houdini

i just had a little fun with particles and AOV renderings. i’ve cached out a simple particle simulation. after i’ve created a shader with different AOV output’s, like speed, density, pressure etc….
this shader can do a nice sparkling or glitter effect. the AOV are also visible in houdini opengl for realtime feedback. the best things is the spec color are baked into attr, so its fool-proofed for stereo rendering.

now i’ve played in nuke to create a interesting looking effect.


and same opengl feedbacks:

volume axis field in houdini

if you come from maya fx field the first thing you will miss is  a kind “volume axisfield”  from houdini there always more then one way to get to the desired result. the simplest way to use metaballs.

i’ve  use a cycle primtive to copy metaballs (copy-node) to get torus shape. no just need add force node to copy sop and use the attractor inside the pop network. with correct settings it will create nice swirling motions like in this example.

this methods is nore flexible then volume filed in maya. the force can any shape build form metaballs. its not fastest methods but most situations, its good enough.

another example of the attractor node:

houdini waterfall levelset 1 setup

thats idea for an setup which i had back in avatar days when was working on the waterfall sequences. the waterfall setup in houdini is much easier. the data in houdini is much better to control. i am using 2d version of mountian texture to drive the mass and the velocity of the particles. i am faking air pressure with same vop pop operations. the result is pretty fast and under good control, i get the shape which i wanted.  the color show different level like density, pressure etc…

the next step is feed all the data into mantra rendering. mantra works wuite well but for close of water  –> i need a fast raytarcer like modo or vray. that will my next step. with current simulation setup i can push the details to the level i needed at still pretty fast sim times.

(its little slow, just realize the paramters –> final output should have the correct speed)

crashing wave setup

done in maya with nparticles and a same expression on collison, bounce and stickness.
sim time was 30 minutes on myold macbook for this 1000 frames.
this is first state of levelset. second simulation should triple the density and detail. overall is dirty fake for crashing wave. but the details looks promising and the simulation times are really fast.

i scattered some point for prepare meshing and rendering in modo fo this first levelset.

new old waterfall designer tool

i had time to optimize my rig for old project:
this is a quick demo of realtime preview of my waterfall rig. the volume represents the implicitly volume rendering in renderman. i used couds shape to show in maya opengl the size and opacity of the implicit volume (renderman).

here example of my expressions setup for faking air pressure:

this is a screen of my adjustable volume emitter for my waterfall rig. i can fit the emitter to edge of the rocks and adjust the amount of water on each position with a ramp:
i hope i can post a video with all “water-structure” feature of my rig.