Illumination of Image-based Objects

A new data representation of image-based objects is presented. With this representation, the user can change the illumination as well as the viewpoint of an image-based scene. Physically correct imagery can be generated without knowing any geometrical information (e.g. depth or surface normal) of the scene. By treating each pixel on the image plane as a surface element, we can measure its apparent BRDF (bidirectional reflectance distribution function) by collecting information in the sampled images. These BRDFs allow us to calculate the correct pixel colour under a new illumination set-up by fitting the intensity, direction and number of the fight sources. We demonstrate that the proposed representation allows re-rendering of the scene illuminated by different types of fight sources. Moreover, two compression schemes, spherical harmonics and discrete cosine transform, are proposed to compress the huge amount of tabular BRDF data.