Interactive near-field illumination for photorealistic augmented reality on mobile devices

Mobile devices become more and more important today, especially for augmented reality (AR) applications in which the camera of the mobile device acts like a window into the mixed reality world. Up to now, no photorealistic augmentation is possible since the computational power of the mobile devices is still too weak. Even a streaming solution from a stationary PC would cause a latency that affects user interactions considerably. Therefore, we introduce a differential illumination method that allows for a consistent illumination of the inserted virtual objects on mobile devices, avoiding a delay. The necessary computation effort is shared between a stationary PC and the mobile devices to make use of the capacities available on both sides. The method is designed such that only a minimum amount of data has to be transferred asynchronously between the stationary PC and one or multiple mobile devices. This allows for an interactive illumination of virtual objects with a consistent appearance under both temporally and spatially varying real illumination conditions. To describe the complex near-field illumination in an indoor scenario, multiple HDR video cameras are used to capture the illumination from multiple directions. In this way, sources of illumination can be considered that are not directly visible to the mobile device because of occlusions and the limited field of view of built-in cameras.