Perspective projection through parallel projected slabs for virtual endoscopy

Virtual endoscopy is a promising medical application for volume rendering techniques where perspective projection is mandatory. Most of the acceleration techniques for direct volume rendering make use of parallel projection. This is also the case of the current generation of VolumePro systems, which achieve real-time frame rates but unfortunately just provide parallel projection. In this paper, an algorithm to approximate perspective volume rendering using parallel projected slabs is presented. The introduced error due to the approximation is investigated. Based on the error estimation, an improvement to the basic algorithm is presented. The improvement increases the frame rate keeping the global maximal error bounded. The usability of the algorithm is shown through the virtual endoscopic investigation of various types of medical data sets.