Friday, December 26, 2008

Angkor Wat in 3D Revisited

Several months ago I wrote about a 3D feature extraction project based on aerial photography at the temple complex of Angkor Wat in Cambodia. While photogrammetric reconstruction is one avenue of documenting historical sites, another method is terrestrial laser scanning. While Cyark has been mentioned before, I thought I'd highlight the foundation again here since it is such an excellent resource for terrestrial laser scanning in the context of archeology and documenting cultural heritage.

Aside from the slick presentation, one of the really nice features of the website is a 3D point cloud viewer, which allows you to navigate various scenes in 3D. While the point clouds are pre-cooked for the viewer (which has a 2 million point limitation), the density is still enough to provide a very realistic experience. You can even see a couple of people in the "Outer Cruciform Courtyard at Banteay Kdei". The process for digital heritage preservation is outlined quite well in this paper.

Angkor Wat 3D Model

Point Cloud: Outer Cruciform Courtyard at Banteay Kdei

One question this raises is which technology, photogrammetry or laser scanning, is the most effective (cost, quality, processing time, etcetera) for cultural heritage projects. For a study on that, check out this paper, which compares terrestrial laser scanning with "terrestrial photogrammetry" (photos are taken from the ground with an SLR camera, not aerial photogrammetry although the processing principles are similar). As one might expect, the study indicates several pros and cons of each method, as well as a look into combining methods. The cost of hardware is higher with terrestrial laser scanning, and the processing (automatic and manual) for both methods can be fairly intensive depending on the level of detail and accuracy required.

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