Psys demo 2: Location Emitter and Mesh Emission

So i fiddled around a bit more with the idea of having attributes but decided against it.
It added a lot of complexity and work-arounds into the mix and seemed like an overkill
for now.


Here's another video showing a comparison between location emitters and Mesh emissions.

Psys: demo 2: Location Emitter and Mesh Emitters from bhavesh pandey on Vimeo.


So for now I have decided to focus more efforts on implementing Ray-Triangle intersection
routines for the particles and hopefully implementing an accelerated data structure for fast neighbour
lookups (but nothing too elaborate).
Maybe another weekend.

Psys demo 1: AABB

Ok, so I have added a kill() routine as well as another routine to compute an
Axis Aligned Bounding Box for the Particle system along with another routine to
draw this AABB.

Psys demo 1: AABB from bhavesh pandey on Vimeo.

Now, I would quite like to implement 2 more things into this.
1) Ray / Intersection capabilities akin to Houdini's Ray SOP for basic collision detection etc.
2) An accelerated data structure for fast neighbour lookups.

After this I'm pretty sure I'll have most of the things I'll need for the time ( :D )
I would like to spend some  time cleaning the code and then profiling + optimising it further
along with some other projects I have in mind.

Will post another update later..

Ciao.

Using volumes for Particle-Object interaction and velocity updates.

I was doing research on volumes for a particular project at the University. The core of the research was based on how we could get correct dynamics behaviour in a Particles-Object simulation. Following is a Particle-Object system I did in houdini to get correct Velocity transfer updates using an SDF representation of the colliding object.

This setup uses POPs and is faster than a FLIP simulation. Additionally it could be coupled with additional systems using conditions based off curvature of the object or the velocity of the object.

Here's a short flipbook:



following are some screenshots from the same test:





I'm still continuing to work on these and how volumes could be used to achieve some highly detailed movements in particles. Also going through some books on levelsets at the moment, would be posting some more results later.

ODE Solver..and some fun! (ode to ODE Solver!)

this is flipbooked sequence of a Rigid Body Simulation with in Houdini using the ODE Solver..

Actually this is more of a Hybrid..using POPs, VOP POPs, SOPs, and DOPs in Houdini..

There were 2 DOP simulations used for different purposes..

The Particles were also Advected to get a specific movement.

Main intention behind this was simply my NEED to work with the ODE Solver. ODE is mainly used for Dynamics in gaming and cant work with complex geometry..So I made up a Truck (sort of :P ) using simple primitives and used that for the Dynamics..

Though ODE Solvers are much faster than Houdini's RBDs, there's a lot of difference between the accuracy and the ability to handle Complex Geometry within a simulation.

SESI implementing ODE in Houdini is awesome! Now we have a choice in case we want just a Pre-Vis or if we are working with simple Geometry types.

The simulation for DOPs took no more than 4-5 seconds per frame..(sometimes lower than this)

POPs and VOP POPs was almost realtime..

Specs:

500 different RBDs simulated together.

DOPs Sim time: 4-5 secs per frame. (max..sometimes lower than this)

which is amazingly fast considering my system configs:

2GB RAM,

intel core 2duo, 2.1GHz, 32 bit, WinXP

Fluid Simulation....(of a Viscous and thick fluid)

This literally ate my head off....the simulation was pretty straight but what actually took time was retiming entirely and deleting the stray particles..since i needed the mesh to also stretch I lost the luxury of "Exclude the Lone Particles" option :(

this is a low res version..the original simulation turned out to be very fast but the movement of the fluid was pretty good....so I retimed the entire simulation using a custom Retime node (scripted in Python by Michael Rice) further there were quite a few stray particles which were deleted using ID attributes using a customised setup within Houdini. This could also be done using one cheap solution but its very heavy on the processing side..(sounds so Ironic....haha).

Also, I'm working on few other effects..will post updates once they are finished.

few of the experiments with the color and look can be seen in the pictures..please note that these were low resolution test render pictures

The Biblical Flood..of CHOCOLATE :D (fluid simulation)

hhmm..things moving pretty good and fast this once..(is it because my college is over??..hmm*thinking* hehehe)

orrighty..so here's the Fluid Simulation I had posted last time....just few changes though

I made it lot more Viscous..I wanted to give different look kinda like a chocolate..

I am facing some issues though..as is always the case..things tend to get nasty with me....good thing is..i'm nastier than them hahaha

Ok..lets move on..

I have some Self Shadowing artifacts as you can see in the picture. Issue is if I increase the bias and raytracing intersection distance..I'm losing a lot of shadow detail..

Wanted to see both the pics (i.e. with and without Motion Blur) just for fun of it..

I have thought of some camera movements and stuff but nothing specific as yet.

PS: well thats enough about 'the Biblical Flood of Chocolate' :D

The wetmap implementation is still not complete..but its almost there..(trust me guys I know it..I have done it before :P )

(yeah i know..still not there with the ART of cracking FUnnY jOkES )

flood in the bathtub??

i'm getting terribly restless..reason??

one of the most frustrating thing for me is no longer there to eat my head off.

Since I had worked on Realflow (which I really liked), I could not really get my grasp on the particle fluids in Houdini.

I cant really blame Houdini for this....its all my misunderstanding. I was trying to work on Houdini the way I used to in Realflow. Having said that I must say, Houdini and Realflow are very much alike if some of the things are cleared when you switch. In a way Houdini gives far more control to the user as compared to Realflow.

I'm not taking anything away from Realflow because I simply cant. Its made for fluids and dynamics....I do also feel its faster than the fluids in Houdini.

I use Houdini fluids for the simple reason: MORE CONTROL.

Realflow did not have a official Houdini export until now (there's a beta version Realflow plug-in for the same..for more details on this please cheack Odforce.)

And since I have been working on Houdini primarily for everythin, I cant really use RF fluids.

Also there's a lot of control which if leveraged properly, can get you amazing results.

Anyways, I used to be really irritated because of lousy and stupid looking meshing of the Particle Fluids....which I again confess was my lack of understanding.

Finally while working on this personal project the solution dawns upon me.

Its got to do with the Particle Seperation.

If you have a high seperation (which I used to keep high to get better speed) the partcles will be farther away from each other and thus when meshed, the mesh turns out to be entirely stupid. (come on I could draw up a better mesh on paper than THAT).

This once, I kept the separation lower, keeping sure it not unnecessarily slowing my system (a value lower than 0.1 but higher than 0.01 usually gives good performance/quality ratio) I tried to get the desired look changing parameters like Bounce, Friction etc.

Once I got something similar to what I wanted, then I would try to up the resolution.

Well to be honest, I also cheated a bit as far as resolution of the sim is concerned.

Ok, its still in a Work In Progress image so I have got a screen capture and a quick test render done (which is nothing fancy: no motion blur..no texture etc).

almost done with the wetmaps implementation. (Houdini doesnot generate wetmaps straight out of the box..but to learn how it could be done is even more fascinating!)

Will update later :)

PS: please ignore the title....it's another side effect of my self imposed isolation haha :D

choco........late!!

this is a quick post because i gotta catch up some sleep now.

this is a simulation for (technically its not a simulation, as it does not involve correct physics..but still i just wanted to mimic that moment) molten chocolate falling on the surface....

done using only POPs within houdini (POPs with no dynamics..just particle context forces etc)

will update about it later when i wake up....

buona notte :D

PS: choco........late is just a choco sim gone late!! (aaarrrghh)

abomination!! ------->volume shading and rendering

this is not some abomination bashing up the hulk..

i was pretty saturated with the crater project and decided to take a break

to do some fun stuff!

Having always wanted to get my hands on a scene where something breaks and releases

particles into air.

Well, so I decided to get going with a scene where a sortt of a statue falls on the ground and breaks

releasing dust in air.

The result was pure ABOMINATION!

The spurt of dust looks more like a bomb explosion's smoke.

Clearly I increased the number of particles being emitted in my utter enthusiasm.

No complains....learnt great stuff about volumes and shading volumes etc..More importantly,

got few ideas for the shader used for the smoke!

I'm putting a Low Res test render pic up here.