ground covered with stones

# 1 06-10-2008 , 09:35 AM

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Location: vienna

Posts: 1,095

How would I go if I want to simulate a ground covered with little stones like on the picture below?

my first idea was to create a particle cloud, apply gravity to them and let the particles then fall into a very flat open box to completely fill it.

things to find out:

- applying stone-like objects per particle. (does a random radiusPP pass values to the objects?) is it even possible to connect spheres to the particles? how do I connect them?

right now I have the box, particles and gravity. the particles fall until they collide with the box and bounce back waaay to much. (conserve energy..?) or do I have to use Per Particle Expressions to controll things like Velocity etc...?

lots of questions. I will do research now, and probably post results to my own questions. but I am sure there are some issues which take me more time than I have for this. so I wanted to post it as soon as possible.

hope you guys have some ideas!

thx

------
ah yes! forgot to tell.
the reason I start this so complicated is because I need a track from a caterpillar in the end which moved along the ground and left overlaying trace marks. I thought it would be the easiest thing to dynamically create this stuff since I need all different maps in the end. Diffuse, AO, Normal, Spec etc..

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everything starts and ends in the right place at the right time.

Last edited by Falott; 06-10-2008 at 09:38 AM.

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# 2 06-10-2008 , 04:31 PM

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Location: Minnesota, USA

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Just out of curiosity, are you going to be interacting with the stones at all?
Or are you just having them lay there on the ground?

I ask because this can be achieved in a variety of ways, some easier, and less heavy than others.

Lemme know user added image

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 3 06-10-2008 , 06:10 PM

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Let's say they just need to lay there for an instance? (It also interests me. I could have used something like that for a scene I did lately...)
Thanks,
Benny

When in doubt, delete history and freeze transformations.

My latest snake game
(Requires DirectX9 SDK and Framework)

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# 4 06-10-2008 , 10:22 PM

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Well, whether or not one wants them to simply rest on the ground, OR if one wants to interact with them, here is a list of ways to achieve this - and their proper uses:

---Maya i.e. 3D:

Particle Instancing - The particle intstancer can take a handful of randomly-shaped objects and randomly emit them over the entirety of a given surface with or without dynamics involved. Best solution for true 3D, light/shadow/dynamics etc.

Sprites - same deal as above, but not true 3d and thus cannot hold up at extreme off-angle shots, among other caveats such as clipping, loss of lighting control over a fake-3d surface, etc.

Scatter Melscript - Same as duplicate-special, but with randomized resulting positioning. Caveats include only being able to duplicate one rock at a time, so random looks with multiple objects are extremely difficult if not impossible.

Projection Mapping - Same as sprites, however, just one or more larger pieces of geometry (the road in this case) that is textured with a painting.

---In Post i.e. 2D:

Particles - If one has access to an advanced compositor with FBX-import ability such as Fusion, Flame etc. you can import FBX geometry and simply texture your geometry there. One advantage to this method is the ability to bake-out a Normal Map to control situations where you may need to completely relight your scene in post.

Sprites - Same issues as 3D above.

Projection mapping - Same issues as 3D unless you are using an advanced compositor like above and you can generate sphere particles there and color them with some rock material or project a texture on them.

Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com

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# 5 07-10-2008 , 02:57 AM

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first of all - thank you for your replies.

yes, interacting is the keypoint. goal is this: a ground covered with random sized stones. then a caterpillar will drive through the scene in circles and will leave tracks from its chains. I allready thought about to paint it in ZB but i am bad at painting, that´s the point. the scene is taken then for a realtime renderer and I´d like to use as much geometry as possible for the performance or just bake out a lower res geometry and hiRes normalmap. but since I need to achieve as much "photorealism" as possible for the final result I think it would be the best to simulate the whole stuff with real chains moving through real stones and get a natural result.

I allready tested a softbody simulation with a 200x200 nurbspatch and a ball rolling over it. allthough the resolution could be much more for my needs the calculating times are allready incredibly high. I could let it render over night but I fear that memory issues will arise.

I guess the particle instancer will be the next way to go.

everything starts and ends in the right place at the right time.

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# 6 07-10-2008 , 03:01 AM

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Location: IL

Posts: 738

Thanks, Never used particles before though... I've got so much to learn and still an unfinished project...
Thanks again,
Benny

When in doubt, delete history and freeze transformations.

My latest snake game
(Requires DirectX9 SDK and Framework)

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# 7 07-10-2008 , 03:32 AM

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Posts: 1,095

ok, particle instancing works fine (again apart from calculating times). I think it is best to connect them just in the end after the simulation of particles falling down went through. but I need the particles coliding with themself. I followed a tutorial where one used a radialField per particle. this seems to work but creates a pattern in areas with high particle density. it´s said that maya has no feature of intercollision between particles themselves.

i´ll try this plugin soon. but for now I am going to have a day off user added image

https://br.geocities.com/laloschmidek...sionField.html

download it here

https://www.highend3d.com/maya/downlo...ield-1949.html

____edit-----

aaaww - it´s maya v4 and v5 only

everything starts and ends in the right place at the right time.

Last edited by Falott; 07-10-2008 at 03:35 AM.

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