Displacement is one important feature that most GI renderers support. Here we would be specifically speaking about mental ray displacement techniques.
If you were to use the displacement modifier, a heavy mesh is a pre requisite.But with these GI renderers, the displacement is calculated at render times . So heavy mesh is not required to get good displacement.
I have tried to explain some simple but efficient methods on how we could get a considerably good displacement with these renderers. Then it could be grass, cloth, carpets, fur, rock surface, or almost anything that you could imagine; all you need is a displacement map and the shader(and ofcourse the GI renderer)
One good question that may arise for a few- What are displacement maps?
Ideally they are similar to bump maps. The only only difference being, bumping doesn’t deform your mesh.Neither does it subdivide your mesh. But displacement subdivides the mesh according to the input greyscale displacement mas. These maps are in desaturated maps wherein the white areas are lifted, black regions are sunken during the displacement process.
A few examples might help explain the displacement process. Lets try displacing grass. I prefer using 3ds max( dats my preferred tool of trade ). Displacement works equally good with other 3d packages.
I created a plane with segments 30 x 30. That’s enough since mental ray will displace the mesh subdividing it while it renders. I converted the plane to Editable poly and instead of using the noise modifier, I used the push pull paint deformation, to get the uneven ground. Lets choose Mental ray as the renderer.
And these are my Mental ray settings:
Lets make the grass shader. We will use the mental ray basic template shader. Then use the DGS mat for surface shader and our displacement map in the displacement slot.
You can get the grass material from here
http://img252.imageshack.us/img252/2901/kissos2xxlc4xe.jpg
And the displacement map here
http://img371.imageshack.us/img371/8858/kissos2xxlb0sd.jpg
Here are my material settings.
Mental ray shader for grass.Dgs shader for the surface mat and height displacement map for the displacement
The diffuse map is the grass map that I have included.
Height map is the displacement map that I have included
This is a screenshot of my viewport.
I included a skylight with multiplier 1
And a mental ray area spot for the sun. with multiplier 0.85.
We are all set. Just hit render. Sit back till mental ray calculates and renders out the beautiful displacement. Heres what I got.
Pretty simple?
Let me show you this effect on a sphere to closely seehow the grass is actually displaced
Remember to UV map the model before you even use displacement on it.
You may try changing the settings for displacement. Max level helps you get detailed displacement even wid a low poly mesh. However the rendering time increases with the increase in max level.
Similarly I had lots of fun doing fur and skin scales, using different bitmaps and displacement maps. Different displacement maps, different height displacement settings.
Here are few of them
Next I would probably brief up displacement in vray and brazil
Any questions? You may write to us.