Collisions between a minimally invasive surgical instrument and patient tissue are prevented in various ways. In one aspect a body cavity is mapped by recording positions of a surgical instrument, and the map is used to insert another surgical instrument. In another aspect, a surgical instrument is inserted into a space vacated by a guide tube. In yet another aspect, a volume is defined in which a control system permits an instrument to move, and the volume is a sum of one volume that is defined by previous movements of the instrument and other volume that is defined by the boundaries of an image capture component. In yet another aspect, a real time image of a surgical site is mosaiced over a previously recorded more distal image of the site. Surgical instruments are visible in the real time image, and representations of the surgical instruments as they would appear in the previously recorded image are generated and displayed on the previously recorded image. Consequently, a person moving the surgical instruments sees a representation of the instruments outside the field of view of an imaging system taking the real time images.