Accurate image based relighting through optimization
Pieter Peers | Philip Dutré |
Contact: Computer Graphics Research Group
Poster at Eurographics Workshop on Rendering 2002
Abstract
In this report we present a new re-lighting technique that, for a single viewpoint, accurately captures the reflectance field of real and virtual objects, without restrictions on their geometrical complexity or material properties. As a result the objects can be re-lit under arbitrary lighting conditions. To capture the reflectance field, we take photographs of an object lit by several lighting patterns on a surrounding discretized hemicube. The illumination of each pixel due to emitted radiance from each discrete patch on the hemicube is approximated by a reflection coefficient and a rectangular support which are found through an optimization procedure. The discretization of the hemicube ensures sufficient angular sampling to capture diffuse material properties. The use of a per patch support accommodates the small solid angle of a incoming light important for specular materials. To re-light the object, the target illumination, a high-dynamic range environment map, is averaged over the support and multiplied by the reflection coefficient, per pixel and per discrete patch on the hemicube. The results obtained show accurate re-lighting of diffuse as well as specular objects.
Keywords: Image Based Relighting, Light Stage, Environment matting, Illumination patterns, Optiization
Downloads
- EGWR Paper (PDF, 2.3MB)
- EGWR poster (PPT, 71kB)
- Siggraph Paper (PDF, 1.7MB)
- Siggraph Presentation (PPT, 3.8M)
- Technical report (PDF, 3.1MB)