  In this paper, we present an approach to enhance and improve the current
normal map rendering technique. Our algorithm is based on semi-discrete Optimal
Mass Transportation (OMT) theory and has a solid theoretical base. The key
difference from previous normal map method is that we preserve the local area
when we unwrap a disk-like 3D surface onto 2D plane. Compared to the currently
used techniques which is based on conformal parameterization, our method does
not need to cut a surface into many small pieces to avoid the large area
distortion. The following charts packing step is also unnecessary in our
framework. Our method is practical and makes the normal map technique more
robust and efficient.

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