Section: New Results

Axis 2: From Acquisition to Display

Outdoor Lighting for Augmented Reality

Figure 9. Consistent illumination of a virtual car in real outdoor lighting.

In augmented reality, one of the key tasks to achieve a convincing visual appearance consistency between virtual objects and video scenes is to have a coherent illumination along the whole sequence. As outdoor illumination is largely dependent on the weather, the lighting condition may change from frame to frame. We have proposed [17] a full image-based approach for online tracking of outdoor illumination variations from videos captured with moving cameras. Our key idea is to estimate the relative intensities of sunlight and skylight via a sparse set of planar feature-points extracted from each frame. To address the inevitable feature misalignments, a set of constraints are introduced to select the most reliable ones. Exploiting the spatial and temporal coherence of illumination, the relative intensities of sunlight and skylight are finally estimated by using an optimization process. We have validated our technique on a set of real-life videos and show that the results with our estimations are visually coherent along the video sequences (cf. Figure 9 ).