Improving Photon Mapping Towards an Interactive Stage Lighting Framework

In this work we present an improved rendering algorithm for the planning of stage lighting using photon mapping, since existing software implements algorithms that do not suit the lighting workflow in a theatre adequately. During theatre lighting, positional changes of light sources are occuring rarely compared to intensity and color changes: Once a light is positioned and aimed correctly, many intensity and color values are tested. Thus, intensity and color changes must be recomputed very fast whereas positional changes may take longer to be rendered. The algorithm we present provides such fast recalculations and furthermore balances idle times of user and renderer. In our algorithm image synthesis is split into a rendering and a real-time updating process. Additionally the wellknown concept of splitting the photon map into a global and a caustic map is consequently refined to light-specific photon maps and intensity buffers. The presented prototypic system utilizes general purpose API to get further insight into and proof of the concepts. Results indicate that the proposed algorithm can efficiently be used to plan and simulate stage lighting in a theatre.