[Radiance-general] irradiance vs. radiance / luminance vs. illuminance

[Marija Velickovic]

Hi all,

A question related to Greg previous mail:

On Fri, Sep 5, 2008 at 7:13 PM, Greg Ward <gregoryjward at gmail.com> wrote:

> Radiance is W/m2.sr while irradiance is W/m2.  Luminance is lm/m2.sr
>> (cd/m2) while illuminance is lm/m2 (lux).  I think this means radiance
>> and luminance are properties of a (solid angle) source while irradiance
>> and luminance are properties of a (flat) surface?
>>
>
> That is correct.  Bear in mind that certain surfaces do not report
> irradiance, such as glass, which you see through as usual with the -i
> option.


and


> Right again -- sources don't report light landing on them (irradiance),
> since they are considered to be emitters, and thus aren't affected by the -i
> option.
>
>
So if I understand well, when we calculate irradiance image (rpict -i
option) depending of surface materials, for various objects different values
are reported :
*light sources (light,glow) - radiance
*glass - radiance?
*trans - ?
*illum - radiance?
*other materials - irradiance

Please fill the blanks :)

Thanks,
Marija
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