ICE rain

[Pancho]

What I want to achive is realistic rain that falls onto objects, splashes, sticks onto them, drips away or builds little streams on the surface, tearing away static drops and so on. Like in reality, like on a windshield. You see many drops, splashes of rain hitting the glass, small streams off water flowing away to the bottom.

Playing around with polygonizer (I need to export the rain as obj.) I realize that the best results (realistic, organic forms) will be achived when using as many particles per drop as possible. So a single particle for each drop won't do. so when there is a particle emitter, it needs to spawn little groups of particles sticking together.

I checked vimeo and youtube and searched on google for this subject, but couldn't find anything usefull. I've never done anything like this, so any help is appreciated.

As it is intended for HD it needs to hold up visually even in a close up.

What'll be great is if the trails running down the object will be thicker and have more volume at the "head" of the movement and a thinner "tail".

Cheers and thanks for any tips and hints.
Thomas

[gustavoeb]

I would ask this guy:

[Pancho]

Thanks, Gustavo

I played around all evening yesterday with Lagoa. One thing I don't understand is how to spawn groups of particles.

If I use a simple plane as a particle emitter it is no problem to spawn particles across this area. I wonder how I could spawn a certain amount of Lagoa particles at each of these particles. Like 10-20 for each drop. These drops then could fall like regular raindrops onto my object.

The Lagoa material I created didn't stick like water to the surface. I played with the tension and stickiness of the collision object, but the drops easily fell away from this object and didn't slide on it, or were sticking to it without moving anymore.

Although the drops tended to explode easily while crossing sharp edges or obstacles on the collision object. Usually a surface tension of 2 and internal and external pressure of 0,1 gave me results trhat behaved like water visually (e.g. forming drops while floationg in zero gravity).

I although tried to use regular particles, but they tend to not keep their volume when using attraction forces and the coagulate force.

Any tips appreciated.

Cheers
Thomas

[Pancho]

PErhaps Lagoa isn't the best solution for this purpose, but as I don't know how to approach this in an effective way, I'm open to proposals.

But my experiene with the built in polygonizer makes me realize that each drop should be made up of "as many" particles as possible. If the surface of the collision object has something like a "slip" map on it which makes it easier of more difficult for a drop to slip on the surface, the drops would deform while moving on the surface, while the surface tension would take care that they don't tear apart.

Just an idea. I also found a water condensation tut on Caffeine Abuse, which is of some inspiration, but I would like to take it a bit futher.

Cheers and have a good start into the week
Thomas

[Pancho]

For a start i would be glad if someone could advice me how to generate particle "drops". I imagine it this way. Point cloud a generates simple particles on a grid, lifetime one frame. Point cloud b generates as many particles as will fit into the sphere shaped particles of cloud a. Is this possible? Will i be able to use the particle drops in lagoa or sph fluids or the new physics based particle simulation? I am curious for any idea!

Cheers
Thomas

[Daniel Brassard]

Here is some links providing useful information for you to try. Check the ICE tree at the end of the XSI List thread, very informative. There is also a raindrop compound from Victor Fernendez Cotura available.

http://softimage.wiki.softimage.com/xsi ... leMass.htm
http://caffeineabuse.blogspot.com/2010/ ... g-ice.html
http://vimeo.com/34950017
http://groups.google.com/group/xsi_list ... af31e713ee

An oldy but goody, still useful info if you replace the old particle system with ICE Particles!

http://www.inframez.com/papers/xsi_rippulu.htm

Also, the surface hit by the water should have some stickiness to it or the water will slide of it too easily as per the cafeine abuse water droplet tutorial.

My 2-cents, Hope that help!