The price for these advantages is paid by the surgeon, who loses direct contact with the operation site. The necessary visual information is mediated by a specialized camera (the endoscope) and is presented on a screen. While preliminary systems experimenting with stereo optics are already available, today's surgery is usually performed under monoscopic conditions. Due to geometrical constraints posed by the external control of the surgical instruments through the trocar hull, the surgeon loses the manipulative freedom usually available in open surgery to a great extent.

     Performing operations under these conditions demands very specific capabilities of the surgeon, which can only be gained with extensive training. At present, the basic optical and manipulative skills can be learned by using inexpensive, traditional training devices. These training units allow the trainee to learn navigating under monoscopic visual feedback, as well as to acquire basic manual competence. In this way the surgeon becomes accustomed to completing a particular task, but because the real-life effect is lost, he gets only a limited training range in dexterity and problem solving. Additionally, the organs used by these units are generally made of foam, wherefore realistic surgical training is impossible. And while experiments on animals are sometimes used for testing new surgical techniques, practical as well as ethical reasons strongly restrict their use in everyday surgical training.

     Virtual reality based surgical simulator systems offer a very elegant possibility to enrich and enhance traditional education. A wide range of VR simulator systems have been proposed and implemented in the past few years. Some of them are restricted to purely diagnostic endoscopical investigations ( [6]), while others, for example, allow the training of surgical procedures for laparoscopic ([ 1], [ 2]), arthroscopic ([ 5]), or radiological ([ 7]) interventions.