3D imaging systems and algorithms give virtual representations of the real world. New emergent hardware systems can combine virtual information and the real world. Virtual and real information must be also visually confronted in order to facilitate our comprehension of the data. We propose a solution which entails the superimposition of a real image of the anatomical areas visualised in a surgical operation with 3D digital data sets. Unlike other solutions which display virtual images in the real world, our method involves ray traced texture mapping which displays real images in a computed world.