For visualization in virtual reality, two topics are of major importance: real-time rendering and realism. To meet these requirements, modern graphics hardware has to be applied wherever possible. A commonly used method to improve realism without decreasing the rendering speed is texturing. Today, fast texture mapping algorithms are even integrated in low-cost hardware. However, high-resolving and non-distorting texturing is very difficult and sometimes even impossible for non-convex complex polyhedra. Nevertheless, the realism of many virtual reality applications could be improved by using non-distorted textures. Especially in surgical simulation, each anatomical detail has to be placed correctly on very complex models of human organs. For this, a new method has been developed, allowing the interactive placement of high-resolution bitmaps to any desired position on the model's surface. In addition, the visualization quality can be improved by using an antialiasing filter. This method, called arbitrary texture placement, utilizes polyhedron decomposition to split one object of complex shape into N triangles. Treating each triangle of the surface as independent object it is possible to assign them an unique part of the texture space where color information can be stored. If a bitmap is applied to the polyhedron's surface, the involved triangles are determined and the pieces of the bitmap inside the triangle are stored at the corresponding areas in the texture space. An example shows the appliance of the method to an anatomical model of the ventricular system in the human brain, used for simulating minimally invasive neurosurgery.

A special-purpose robot system has been developed for neurosurgery. It contains control mechanisms developed from flight-simulator experience to allow precise motion and force-control using very low-force input. The robot constrains the tool motion to a safe region using methods developed for robotic surgery. These regions are defined pre-operatively using MRI segmentation techniques developed with the help of a simulator, ROBO-SIM. The intraoperative target location is tracked in real-time using ultrasound transducers. By applying updates using the ultrasound probe, safety is maintained by compensating for brain-shift. The overall system is being evaluated on phantoms.