lots of grass

[mumle]

Hi, im trying to make a scene with a huge amount of grass, but when i make the distrubution-map smaller everything vanishes and it says i have to make it larger... So what are the best way cover a huge surface with grass? And there something special I can do to optimize it?

[iToo]

Hi,

There are a couple of parameters that limit the maximum number of items (Display rollout) and maximum density (Distribution rollout). If Forest shows a 'F' icon and doesn't display any items, use the "View Stats" windows (General rollout) to check what is the problem and increase these parameters.

However, there is a good trick to create a grassy field without using a huge number of instances:

- Using Forest, create a grass patch with some hundreds of blades
- In Display rollout, Change "Mode" parameter from "Automatic" to "Meshes"
- Create a new Forest object, taking the grass patch as Custom Object. On this, set Mode to "Automatic" (default value)

... and you get a hierarchy of two Forest objects working together. Adjust parameters to get the desired result. 

For very dense distributions, we usually use a "Full" distribution map, applying a Random Traslation of 20% to avoid the grid effect.

[mumle]

Thanks, will look at it tomorrow when im back at work. Loving your plugin 

[mumle]

It makes it easier to distribute it, but at work we have the pro version and by doing it that way its hard to make it follow a terrain. And as it is now, the most common problem i'm having with grass is the computer crashing when "transforming vertices". We are using vray.

[iToo]

It makes it easier to distribute it, but at work we have the pro version and by doing it that way its hard to make it follow a terrain. And as it is now, the most common problem i'm having with grass is the computer crashing when "transforming vertices". We are using vray.

Perhaps your grass patch is too large to follow the terrain... have you enabled "Align to Normals" in Surface options ?

No idea about the crashing problem, i would need to check the scene.

I just created a grass test scene, you can use it as help. It uses two linked Forest Pro objects + terrain + VRay, requires Max 2009.

[mumle]

so its easier for the memory to use two FP-systems than make the first patch into a single mesh and just use one system?

[iToo]

Not really, because VRay converts it to mesh before rendering. But this way you can modify the patch easily, without re-creating the mesh. Futhermore, would be possible to animate the Forest parameters to create some fancy effect (density, scale, rotation, tint....)

[mumle]

fair enough, I'm just mumle's liver trying to understand himself

[iToo]

I've uploaded a test scene using Mental Ray and Forest LIte (requires Max 2009).  It needs some material and lights adjustments, but could be used as base to work.