High-res to Low-res Casting with Granny

Quality

On the left is the original, high-res version of the mesh, which is comprised of over thirty thousand triangles. This version was texture-mapped and bump-mapped in Maya to the artists' satisfaction, using several maps each 2048 x 2048 in dimension. On the right is the low-res version of the mesh, with just under 900 triangles. The artist created this geometry in Maya using the original subdivision cage of the high-res version and Maya's detail reduction facilities. Granny's integrated Maya normal caster was then used to automatically generate the normal map and texture maps for the low-res version.

As you can see from these screenshots from our test rendering application, the transfer is remarkebly accurate. The only real way to tell the difference between the models is using the profile edges, which of course will always be hard on the low-res model since there is not enough geometric fidelity, or by using areas where there is not enough texture resolution on the low-res model for the caster to capture fine detail (such as in the eyebrows). Obviously, both of these situations are under the control of the artist, who could opt to subdivide certain silouette edges that were important, or assign greater texel density to places where more resolution was needed.