Richard Hughes wrote: > On that note, what does SPECTRAL_NORM mean? I expected it to mean that > all the data vales were normallized to that value, but example.sp > seems to have data values larger than the SPECTRAL_NORM value. It's a bit vague. The intention is to disambiguate 0..1 and 0..100% ranges for reflectance and transmittance. For emission, setting it to 1.0 is safest. Graeme.