Consistent Normal Orientation for Polygonal Meshes

(gzipped Postscript)
Print (PDF) On-Screen (PDF) Slides (PDF)
CGI'04 (250 kB) CGI'04 (270 kB) CGI'04 (270 kB) CGI'04 (1 MB)

The screen version is optimized for on-screen viewing: color plots and hyperlinks.
The print version is optimized for printing: no color plots, no hyperlinks.
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.
normal orientation, mesh repair, visibility, patch connectivity, modelling.
BibTeX entry
    author = "Pavel Borodin and Gabriel Zachmann and Reinhard Klein",
    title = "Consistent Normal Orientation for Polygonal Meshes",
    booktitle = "Computer Graphics International (CGI)",
    year = "2004",
    month = jun # "16--19",
    publisher = "IEEE Computer Society Press",
    keywords = "normal orientation, mesh repair, visibility,
                patch connectivity, modelling",
    address = "Crete, Greece",
    url = ""
In case of problems
In case of problems, please don't hesitate to contact me.
(For instance, if your host is not registered by the world-wide Domain Name Service (DNS), then you will not be able to ftp ...)
Gabriel Zachmann
Last modified: Sat Sep 10 15:56:44 MDT 2005