Consistent normal orientation for polygonal meshes

In this paper we propose a new method that can consistently orient all normals of any mesh (if at all possible), while ensuring that most polygons are seen with their front-faces from most viewpoints. Our algorithm combines the proximity-based with a new visibility-based approach. Thus, it virtually eliminates the problems of proximity-based approaches, while avoiding the limitations of previous solid-based approaches. Our new method builds a connectivity graph of the patches of the model, which encodes the "proximity" of neighboring patches. In addition, it augments this graph with two visibility coefficients for each patch. Based on this graph, a global consistent orientation of all patches is quickly found by a greedy optimization. We have tested our new method with a large suite of models, many of which from the automotive industry. The results show that almost all models can be oriented consistently and sensibly using our new algorithm.