Geometric modelling for virtual colon unfolding

A virtual endoscopie view is not necessarily the best way to examine a hollow organ, such us, the colon. The inner surface of the colon is where polyps are located, and therefore what is examined by the physicians. A flight through the colon using a common endoscopie view shows a smal! percentage of the inner surface. Virtually unfolding of the colon can be a more etficient way to look at the inner surface. We propose two methods to unfold the colon : a method that unfolds the colon locally using local projections, and a method that obtains global unfolding of the colon by achieving a suitable parameterization of its surface.