[Radiance-general] (no subject)

[Christopher Rush]

Could be reasonable. In a diffuse transmission situation I think it should be Luminance (cd/m2) = Back Face Incident Flux (lm/m2) * Diffuse Transmission (%) / Pi...   if your 18W CFL have degraded to 1000 lumens each then 4 * 1000 / 1 m2 * 50% / Pi = 636 cd/m2. Maybe your light box is smaller than 1 m2 but the diffusing surface is probably less than 50% transmission.

Ideally you should try to find a luminance meter you can use to verify your camera calibration in photosphere.

 > I'm interested in finding out what the value of my backlight is (600 cd/m2 photosphere tells me<http://jelleferinga.com/files/P1040667.jpg>).
> Does that seem reasonable? Isn't that perhaps a little low of 4* 18 watt tube lights ( they're old... )?

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