Spatially Varying BRDF (Bidirectional Reflectance Distribution Function) describes how light is reflected at an opaque surface. A spatially varying BRDF indicates that the reflective properties of the surface vary across its spatial dimensions. In computer graphics and computer vision, understanding how the reflection of light changes across the surface of an object is crucial for realistic rendering. A spatially varying BRDF takes into account these variations in reflectance across different parts of an object.

Posts

SVBRDF-Invariant Shape and Reflectance Estimation from a Light-Field Camera

/in /by

Light-field cameras have recently emerged as a powerful tool for one-shot passive 3D shape capture. However, obtaining the shape of glossy objects like metals or plastics remains challenging, since standard Lambertian cues like photo-consistency cannot be easily applied. In this paper, we derive a spatially-varying (SV)BRDF-invariant theory for recovering 3D shape and reflectance from light-field cameras. Our key theoretical insight is a novel analysis of diffuse plus single-lobe SVBRDFs under a light-field setup. We show that, although direct shape recovery is not possible, an equation relating depths and normals can still be derived. Using this equation, we then propose using a polynomial (quadratic) shape prior to resolve the shape ambiguity. Once shape is estimated, we also recover the reflectance. We present extensive synthetic data on the entire MERL BRDF dataset, as well as a number of real examples to validate the theory, where we simultaneously recover shape and BRDFs from a single image taken with a Lytro Illum camera.

Read more