Incident Light Measurement

The distribution and intensity of light incident upon a surface point or in a scene affects the amount of reflected radiance to the camera and more generally the appearance of objects. Knowledge of the incident light can aid in shape recovery through photometric analysis techniques such as shape-from-shading and photometric stereo, or may be used in reducing appearance variation caused by lighting. Various methods have been used for measurement of incident light. Different from algorithms for illumination estimation, incident light measurement does not infer lighting from indirect scene cues such as shading, but rather obtains direct observations of the light sources.