Right then...snow

[pixelmonk]

First off, I'm aware this post could well be a double. I swear I put this up just a minute ago but couldn't find it anywhere. My sincerest if it turns out that I did. On with the show...

So I quickly find out I can do a nice polystyrene and some great toothpaste but success with snow is eluding me.

I've seen various semi-tutorials covering "snowy effects" using the SNOW node and others including bits of bump and specularity to give a model the feeling of being snowed on but each example seems a little half hearted. For a start it gives the snow little or no build up. What about after a heavy January?

There's even a shader on Highend3D but again this is just a speckly blanket to wrap around what ever model is intended for use.

More specifically I'm after a build up of snow over a small object, rather than a blanket of snow over a wide area...

http://www.noobynoobs.net/junk/mobject.jpg

There's obviously a spot of snow modeling to be done.

It's become quite a challenge. So then...

Snow is basically a large group of small crystaline pieces (and therefore micro-faceted?). These pieces are translucent (relatively transparent I guess) but their colective density in a pack prevents much light from getting through. I think part of the difficulty is that snow flakes are reflective and have broad highlights (an educated guess?) giving surface they contribute to (...the crazy path the light must take to travel into a mass of snow) incredibly complex specularity.

So far I've managed to get a good result for only the surface texture (the feel), hence the references to polystyrene. This result forms one small part of the following question...

How does snow react to light and how might I simulate it at a level beyond wrapping a shiney sheet over a model. Er... discuss?
Can't you start by using a simple RAMP for transparency for a snow shader you create from scratch?

[crashd]

This could be exactly what you're looking for :

http://www.highend3d.com/maya/tutorials/snow/

or at least a good starting point. there is a lot you _could_ do to improve this, but once you're on the road im sure you'll come up with lots of other things to do with it.
-dave

[Als]

Check "avalenge" fluids example!
This will get you started big time!


Al

First off, I'm aware this post could well be a double. I swear I put this up just a minute ago but couldn't find it anywhere. My sincerest if it turns out that I did. On with the show...

So I quickly find out I can do a nice polystyrene and some great toothpaste but success with snow is eluding me.

I've seen various semi-tutorials covering "snowy effects" using the SNOW node and others including bits of bump and specularity to give a model the feeling of being snowed on but each example seems a little half hearted. For a start it gives the snow little or no build up. What about after a heavy January?

There's even a shader on Highend3D but again this is just a speckly blanket to wrap around what ever model is intended for use.

More specifically I'm after a build up of snow over a small object, rather than a blanket of snow over a wide area...

http://www.noobynoobs.net/junk/mobject.jpg

There's obviously a spot of snow modeling to be done.

It's become quite a challenge. So then...

Snow is basically a large group of small crystaline pieces (and therefore micro-faceted?). These pieces are translucent (relatively transparent I guess) but their colective density in a pack prevents much light from getting through. I think part of the difficulty is that snow flakes are reflective and have broad highlights (an educated guess?) giving surface they contribute to (...the crazy path the light must take to travel into a mass of snow) incredibly complex specularity.

So far I've managed to get a good result for only the surface texture (the feel), hence the references to polystyrene. This result forms one small part of the following question...

How does snow react to light and how might I simulate it at a level beyond wrapping a shiney sheet over a model. Er... discuss?

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