I've searched the normal mapping thread and i didnt find this tip so I thought I'd post it here.
If you are rendering with mental ray there is a superb time saving feature called 'Round Corners'.
Basically any hard edges the shader sees are automatically 'beveled' using a bump mapping trick.
The cool thing about this is that it's RTT compatible.
Heres a rendered example of the shader in action. both objects have exactly the same geometry.
As as example i created this simple scene containing some boxes and a few bits of floating geometry The boxes are arranged in a grid pattern but obviously as they are not beveld they read as 1 flat surface.
Using a Standard material to bake a normal map i get this
Now if I add a Arch & Design Material to the geometry, scroll down to 'Special Effects' and turn on round corners. I get this:
Ok there are some things you can do to speed this all up.
Firstly turn off Final Gather. this really slows things down
Secondly I've written a script to apply the round corners shader to a standard material which will render quicker
--Create a Standard Material with a round corners shader
mat = standardMaterial()
mat.bumpEnabled = on
mat.bumpMapAmount = 100
mat.bumpMap = Architectural__Round_Corners_Bump ()
meditMaterials = mat
This will replace the material you have in slot 1 of the material editor. the shader fits in the standard materials bump slot. so you can tweak the radius there