I am working with Deflections trying to simulate snow. I have a hilly mesh with lots of subdivisions (this may be a problem?). my question is: is there a way to “catch” the snow on the mesh so the particles above will collect on top?
i have been working with it for a little and i keep running into some strange problems and i can only guess that it is my settings. the particles jump off onto wiered tangents well above the mesh as if… well i dont even know as if. Help?
-zark
is this in the wrong place?
This is in the right place. You could try setting your ground mesh to deflect the particles and give it a very high damping value so that the snow doesnt bounce. I still don’t know that this will give very satisfactory results. You may need to apply the subdivision on your ground mesh first. I doubt that this is your problem, but you might want to check the normals on your deflector mesh as well.
I will try to load up some renders or the blend it self but even with damping at 1 and permeability at 0 the particles leap off tangent to the mesh 1 unit above the mesh (they never actually reach the mesh). I have random movement of particles off and i have just a small amount of inital velocity on.
What i am expecting is that the particles go straight down until they reach the mesh and then stop.
I believe that it makes a difference when both mesh and particle are on the same layer? is that correct?
this is a render of the 150th frame, the particles should be traveling straight down and stoping, but none of them reach the mesh. the particles out to the side are my problem (they all will end up on the same path). they are shooting off tangent to the mesh (so it seems). anybody know my problem?
sorry for the quality.
One thing I have learned about particles is that after you change anything as far as deflectors and their position, you have to hit the ‘recalc all’ button on the particle generator window.
But in spite of that, I have run into similar issues in the following scenarios:
Basically, my conclusions have been that it doesn’t work in standard animation. Does it work any better in game mode with the physics engine? Don’t know yet… haven’t gotten into that. All I can say is that for me, particles are out of control. And what’s the deal with 2nd and 3rd generation particles going twice as fast as their parents? I have beat my head against these walls for hours… nay, DAYS… I have worked through all the stuff in the manuals and the tutorials I could find.
If someone could help us with any of the above tasks, I would dearly appreciate it.
For snow you could make the animation reversing the timeline.
I explain, you emit the snow for the floor using vertex groups, to emit from where you want . then reversing the rendered frames your snow should stick on the floor . You should also make multiple duplicates of the emitter to have more randomness …
The best way to do this would be to use an animated texture to simulate the increasing snow coverage. You could also animate the shape of the ground to simulate the rising level of the snow.
You have to know when to cheat. :)) This is a perfect time for that.
Also, being wintertime, I would suggest using less green for the grass.
I really want to get around to doing a snow tutorial and maybe a blizzard tutorial but, time is short right now.
Good luck.
The best way to do this would be to use the new particle patch. 
It does 20 times more stuff 10 times better with 1/2 the hassle.
reverse the snow falling?!!! delic, its GENIUS love it! also how i plan on achiving the effect is by turing on all unborn particles to simulate the particles collecting on surface. this may have been your idea to begin with but just thought id add it.
BlackBoe: ill try the particle patch out, didnt know there was one.
kernond: i was trying to stay away from cheating as much as possible, although your idea is valid. I wanted the simulation to look more like the flakes were landing, and not have random white spots show up with out any cause as with an animated texture.
Have you tried force fields and deflection forces?
Maybe if you tried to animate it at as a really stiff and powdery fluid.
In the particle patch, you can use brownian motion and air drag. And you can make particles die as soon as they hit the ground, so if you have ‘show dead’ on, then they’ll just sit there.