TVBRDF: Database of Time-Varying BRDF


Documentation

The acquisition and the modeling details of our work can be referred to the following paper:
"Time-Varying BRDFs,"
Bo Sun, Kalyan Sunkavalli, Ravi Ramamoorthi, Peter Belhumeur and Shree Nayar,
Eurographics 2006 Workshop on Natural Phenomena,
Sep, 2006.
[PDF] [bib] [©]


Acquisition Rig

This video illustrates our acquisition rig in action:


As shown in the above figure, our system is composed of four key components:
  • Four Dragonfly color cameras (operating at 25 fps and 640 x 480 resolution) mounted on an aluminum frame
  • A sample plate with adjustable tilt
  • A programmable Adept robot
  • A light arm holding a halogen light source and a diffuser.
The four cameras lie in a vertical plane. All the camera optical axes pass through the center of the sample plate, which has four extensible legs to adjust its height and tilt. All sample materials are prepared as planar patches and placed on a tray on the plate, as shown in the inset of the figure. The light source has a stable radiant intensity and the diffuser is used to make the irradiance uniform over the entire sample. The robot moves the light source around the sample plate along a semi-circle.

This design affords us two critical advantages over other BRDF measurement systems:
  1. We are able to scan materials very quickly. Every semi-circle the light source navigates takes 12 seconds. We move the light source across the sample 3 times and capture images with varying intensities. Each measurement thus takes only 36 seconds and this enables us to sample the time axis of the TVBRDFs very finely.

  2. We are able to capture radiance values at every half degree of the plane of incidence (12 seconds * 180 degrees / 25 fps = 0.5 degrees / frame). This dense sampling allows us to measure and fits specularities accurately even for very shiny materials.

TVBRDF Database Home
Contact: tvbrdf@cs.columbia.edu
Last modified: 06/03/2007