Efficient unfolding of virtual endoscopy using linear ray interpolation

Unfold rendering enables us to understand the internal structure of organs more precisely. The most commonly used unfolding method is to cast rays radially along a pre-computed camera path. However, this may produce images of false pathological structures. Details on the organ surface may be lost when the organ's curvature is relatively large due to adjacent ray planes crossing. Several methods are presented to avoid the penetration of ray planes. These methods result in severe computational overhead. We propose an efficient method of penetration-free ray casting for unfolding. It computes ray planes that do not intersect neighboring planes, using the noble intersection avoidance method. It determines the direction of all the rays fired from intermediate sampling points, by linearly interpolating the direction of the rays on two of the original ray planes. Experimental results show that it does not produce erroneous images since it exploits simple linear interpolation.