A Large Carton

[brucelay]

Hi there,

I am making a shot having a big heavy carton dropped on the ground. I am planning to use spring to help me to add some realism on the carton's shape itself. But I am still not sure how I should manage the dust. (especially the momeny that the carton contacts with the ground) Could anyone show me the direction of how this dust effects could be done?

thank you for your attention!

[Marc]

Hey Bruce

One way that I sometimes do it is to cookie the ground plane with the falling object and set it to 'crease'. That way you get a curve along where the two are intersecting (move the ground plane up slightly if you need to. After that I screw with the normals for a while and use that as my source geometry.

I'd also like to hear if anyone has any other preferred methods of doing the same thing.

M

[Val]

Hey.

I was trying to do simular FX long time ago...

and best result I get with fluids emiting from particles...

here is example/one of my tests :

(it is not houdini)

(I think will be very dificl to do nise-SWIRLing just with particles)

(click on pic. to see quickTime movie)

[grasshopper]

The place to start is with good reference. I did a search for slo-mo movies with dust and found a couple of examples. They aren't ideal as you really want a light object landing on a dusty floor but this gives an indication of the swirls that appear in dust after an impact.

Man walking and kicking up dust

As to how to simulate the swirls well Marc's idea seems like a good way to get the initial blast direction. I would look at adding angular velocity with a turbulance function next to see if I can get a billowing effect.

john

[Jens]

I remember having done somthing similar: My idea was to have 3 levels of particles.

1. The 'first level' particles are only there for the initial direction. Like Marc suggested with a line emitter / trigger the emission with a collision event. Fairly few particles (~100)

2. The second particle generation orbits around those particles of 'level 1'. They were responsible for the swirly motion. (a few for each particle of level 1)

3. Those particles of level 2 acted as attractors for the large amount of particles of level 3. Level 3 particles had a fair amount of 'drag' + noise etc. and their opacity was linked to their velocity.

The good thing about such approach is that you have more or less seperate control on the different detail levels of the animation. Didn't look perfect, but it did the job well enough

Jens

[brucelay]

I did some simpel test with the particle but I found the most difficult part is to create the volume look of the smoke. Since there is no fluid in Houdini i am think about using some cloud shader mapped on each particle. Does anyone got any experience in making this type of shaders?

I remember having done somthing similar: My idea was to have 3 levels of particles.

1. The 'first level' particles are only there for the initial direction. Like Marc suggested with a line emitter / trigger the emission with a collision event. Fairly few particles (~100)

2. The second particle generation orbits around those particles of 'level 1'. They were responsible for the swirly motion. (a few for each particle of level 1)

3. Those particles of level 2 acted as attractors for the large amount of particles of level 3. Level 3 particles had a fair amount of 'drag' + noise etc. and their opacity was linked to their velocity.

The good thing about such approach is that you have more or less seperate control on the different detail levels of the animation. Didn't look perfect, but it did the job well enough

Jens

[Val]

I did some simpel test with the particle but I found the most difficult part is to create the volume look of the smoke. Since there is no fluid in Houdini i am think about using some cloud shader mapped on each particle. Does anyone got any experience in making this type of shaders?

if you use lots of particles with good adjustment you will get nice volume look,

I think it will be very "poor" compared to the way fluids moves.. but will looks nice

(for example you can use spheres with noise textures)

example--> quickTime.mov with lots of particles and spheres with noise-map

[brucelay]

HI Val,

Your Dust effects looks very nice! This is exactly the effects I want.

thank you for giving me the hint about using spheres with cloud!

if you use lots of particles with good adjustment you will get nice volume look,

I think it will be very "poor" compared to the way fluids moves.. but will looks nice

(for example you can use spheres with noise textures)

example--> quickTime.mov with lots of particles and spheres with noise-map

[Val]

HI Val,

Your Dust effects looks very nice! This is exactly the effects I want.

thank you for giving me the hint about using spheres with cloud!

you welcome..

(.. same metod like Mark sad.. I am emiting particles from curve/intersection..

and then based on velosyti of sphere generates number of particles and speed)