Estimating Outdoor Illumination Conditions Based on Detection of Dynamic Shadows

The paper proposes a technique for estimation outdoor illumination conditions in terms of sun and sky radiances directly from pixel values of dynamic shadows detected in video sequences produved by a commercial stereo camera. The technique is applied to the rendering of virtual object into the image stream to achieve realistic Augmented Reality where the shading and the shadowing of virtual objects is consistent with the real scene. Other techniques require the presence of a known object, a light probe, in the scene for estimating illumination. The technique proposed here works in general scenes and does not require High Dynamic Range imagery. Experiments demonstrate that sun and sky radiances are estimated within 7% of ground truth values.