GenBSDF matrix for solar band

1

I’m learning GenBSDF and I want to check if my understanding is correct. The XML file from GenBSDF only includes results for the visible band. So is there any options to tell GenBSDF to generate matrix for the solar band as well, or because no spectral data is provided then the matrix for visible band is the same as that for the solar band?

I really appreciate your help.
Fan

1 Like
2

While there are no options to specify solar or NIR bands, you can always provide a model whose reflectances, etc. correspond to different spectral integrals. You can then edit the (presumably Klems) XML file to change the spectrum specified in the following tags:

		<Wavelength unit="Integral">Visible</Wavelength>
		<SourceSpectrum>CIE Illuminant D65 1nm.ssp</SourceSpectrum>
		<DetectorSpectrum>ASTM E308 1931 Y.dsp</DetectorSpectrum>

Unfortunately, I’m not versed in how these are used, so I’m not sure what to replace them with, but you can probably copy tags from an XML file produced by the WINDOW program.

Cheers,
-Greg

3

Thank you. I see. GenBSDF is unable to generate reflectances/transmittance for other spectral integrals except visible band, and if I still want to provide a model reflectances/transmittances correspond to these spectral integrals, I could manually edit the XML file by adding new tags.

4

Well, setting reflectances and transmittances along with geometry is always your responsibility when you provide a model for genBSDF. You just need to make sure that whatever coefficients you use correspond to your desired spectral band.

5

So for a certain spectral band, I specify reflectances and transmittance along with the geometry, and then the results from genBSDF are matrics for that spectral band although the label in XML file is “visible” as the following picture shows.

image
image1067×305 44.8 KB

6

Yes. The red, green, and blue channels in Radiance correspond to any wavebands you like, you just need to set the values accordingly. They are more or less independent of each other until the final summation to a Y channel. If you set them in unison, your BSDF data will correspond to your selected waveband.