Relightable texture for use in rendering an image

摘要

Free-viewpoint rendering is improved by determining a colour component of a relightable texture and surface normals set, preferably pre-rendering to quicken rendering on weak devices. View analysis (204) estimates scene geometry (e.g. model) and segments initial (e.g. blended) texture (I(x)) into materials, the initial texture being separable into a colour estimate and a corresponding shading estimate. Initial coarse colour estimate is determined (206) for each material. Scale factor(s) are determined (208) for scaling the initial coarse colour estimates relative to each other for materials to appear lit by similar irradiance. Scale factors are determined based on differences between irradiance estimates determined for the materials based on shading estimates which correspond with scaled versions of the materials initial coarse colour estimates. Global irradiance function is determined (210) describing scene illumination using determined scale factors. Global irradiance function and initial texture determine (212) a further colour (A(x)) and corresponding shading estimates (S(x)), the former representing the colour component of the relightable texture. Surface normals set (nopt (x)) is determined using the global irradiance function and further shading estimate. Separating colour from shading allows relighting of the scene by applying different lighting effects to colour estimates. Surface normals allow correct application of lighting effects to the colour estimate.