8

150 Chapter 17: Rendering
Normal bump maps corrected using Flip Horizontal
Red and blue are more evenly distributed, with blue
predominating.
With the maps corrected, the full rendering,
whether with 3ds Max or a hardware renderer,
looks better.
Corrected normal maps render more smoothly, without
discontinuity.
Thearrowsshowhowthemapsarecorrectlyalignedto
wrap around the pant legs.
Noise when Render i ng a Nor ma l B ump
Map with the mental ray Renderer
If you use the mental ray renderer to render a
normal bump map, and the model has overlapping
faces (for example, where the low-resolution and
high-resolution objects overlap i n space), then
thenormalbumpmapcanshownoisewherethe
faces overlap.
Red areas show noise from overlapping faces
The workaround is to adjust either the high-res or
the low-res object s o that faces are not coincident.
One way to do so is to use a
Push modifier (page
1–769)
. After you have generated the normal map,
you can turn off the Push modifier .
Tip: If another object in the scene continues to
cause problems with the map rendering, you
can make it invisible to normal projection by
going to its Object Properties dialog, and in the
Rendering Control group, turning off Visible To
Reflection/Refraction.
Over l appi ng UV Coordina tes
Overlapping UV coordinates can cause rendering
errors in Render To Texture. The problem is
especially noticeable on characters that have