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148 Chapter 17: Rendering
The reason is that with the default projection cage,
the rays par allel the sides of the indentation, and
so details are lost.
Projection rays (shown in red) parallel the sides of the
indentation.
To c o r re c t t h e p ro b l e m , you c a n m o ve t h e e n d o f
the cage upward, and scale it inward a little, s o the
rays don’t run s o nearly parallel to the side of the
indentation.
Raising and scaling the upper end of the projection c age.
When the cage is adjusted this way, the indentation
appears in the normal bump map.
With the corrected cage, the upper indentation appears
correctly in the norm al bump map.
Tip: In situtations like this, another solution can b e
to use Break on the vertices in the region of the
low-resolution object where detail is missing from
the map. This increases the number of vertices
in the cage, and reduces the chances of geometry
being missed. If you use this metho d, it is likely
you will need to make further adjustments to the
projection cage, as well.