Grass

Creating the grass dust and other vegetation for the desert scene was one of the biggest tasks. To make the grass look convincing it had to be spread as far as the eye could see this involved different levels of detail so that the close ups would show individual blades of grass and in the far out shots its still possible to make it out.

Using the inbuilt scatter command i could spread the vegetation across the scene but this was no where near efficient since the poly could was too great and there was not much control over the spread. after many tries with the scatter effect i decided to settle on using particle instances.

using particles i could control the spread of the vegetation using a greyscale map and by altering an existing procedural i could generate vast amounts of random terrain. The problem with using procedurals is that they are co-ordinate based and could not work with particle spread since particles can only be spread with a 2D map but by uv scaling the plane to the vertex colour map any procedural could be used to generate a surface.

Particles in the background were lower in poly count but still takin a long time to render but by excluing them from the vray sun they did not generate shadows which lowered rendering time and kept the same level of quality.

The same technique for distributing grass was used for dust and dirt since the spread and density could be instantly altered using a greyscale map. Using particles meant i could create a few variants within one sub-shaded model and they would all be randomly distributed.

To improve efficiency i used simple textured planes for the far out shots, these planes had opacity maps that showed each piece individually