We aim to obtain qualitatively correct estimates of g, the coefficient of the HG phase function, for different contaminants. The following image shows our setup, which is similar to the setup for measuring optical thickness patterns, except in two places. First, we use a laser instead of a projector. Second, we use a uniform contaminant layer. We first measure the thickness of this layer. When the laser beam hits the contaminants, part of it will scatter towards the Lambertian board and generate a falloff (or lobe) pattern on the board. The center region will have a very strong spike due to the attenuated laser, while the brightness of other regions is due to the scattering. From this falloff image, we can fit g through optimization.


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The database contains 12 samples, including various kinds of contaminations, plus one example with clean glass which is used as a simple verification. The images of the falloff patterns are high dynamic range and in EXR format. For more information about EXR, visit OpenEXR please. Moreover, we also show the plots of the fitting, in which the blue curves are the fit and the red circles are the measurements.

Click each of the sample in the following table to download. Also, the 12 samples are zipped and can be downloaded together here (46MB). We provide some Matlab code for reading and writing EXR files, as well as code for estimating g here.

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Contact: jwgu@cs.columbia.edu
Last modified: 06/02/2007