Double Check Radiometric Scale Factor Calculation

[benjamin-heasly]

Renderer plugins apply a renderer-specific radiometric scale factor to renderings to bring multi-spectral images into units of radiance. The scale factors are computed with a utility that analyzes the results of a test scene.

We may need to update the utility to remove a factor of two, which we may have included by accident.

The correct conversion involves irradiance for a point at distance, which may be converted to radiance by:

irradiance = pi * radiance (correct)

It may be that we are using this incorrect conversion instead:

irradiance = 2pi * radiance (are we doing this by accident?)

So we should check our code and documentation to see if we need to make a correction:

• in code, including existing renderer plugins, utilities, and example scenes
• in our methods paper?
• on our wiki?

This issue is about determining whether we have an error at all. If we do, we can make a separate issue about correcting it.