1. A system comprising a 3-D display device with a display screen, a means for addressing the display screen, and a renderer having an input for a 3-D model and an input for at least one viewpoint for rendering image information for supply to the addressing means wherein the renderer comprises an initial part ( 70 ) having an input for the 3-D model and for a main view point for rendering objects in the form of a main view point Z-stack ( 91 , 94 ) comprising stack layers (S 1 , S 2 , S 3 ) comprising color information and Z-values, the renderer further comprising a Z-stack constructor in which, from the main view point Z-stack ( 91 , 94 ) generated by the initial stage, Z-stacks ( 97 ) for additional viewpoints are constructed, and a further image information occlusion semantics stage for generating image information ( 79 ) from the Z-stacks ( 97 ).