Projection of 3D space onto a 2D surface relies on the computer graphics camera, which is designed like the camera obscura. The procedure follows the laws of perspective projection and does not explicitly consider the viewer of the rendered image. Our approach is to extend this camera model in order to involve human perception into the rendering of 3D scenes. The aim is to create a user-centred spatial impression by a 2D image. By integrating the user into this process, implicit interactions can be applied to provide interfaces for an efficient and coherent communication of information in virtual environments. This paper introduces user-specific and context-specific parameters that must be taken into account when designing presence-aware applications. To this end, we present a concept of an interactive exhibition based on implicit interaction and point out its applicability in information design of three-dimensional scenes.