[Radiance-general] accounting for irradiance due to ultraviolet in rtrace

[Robert Ong]

Thank you both Greg and Chris. Now, I understand the concept pretty clearly.

Kind Regards,
Robert

On 24/10/11 22:17, Christopher Rush wrote:
>
> An example might be to use a typical sky definition (e.g. using gensky 
> or gendaylit commands), and perform all of your calculations as if you 
> were doing standard lighting calcs. You would get output in values 
> related to lumens (in other words, human-response-corrected visible 
> Watts of spectral radiation). And looking into the units, lux is 
> synonymous with lumens/m2. If you calculate 100 lumens per meter 
> square (lux) at a point using the standard methods, and you know your 
> light source (for example daylight under those particular sky 
> conditions) emits X Watts in the 120-400nm range for every lumen, then 
> your UV component would be 100X Watts of UV.
>
> You would not multiply your material definition by 4, but typically 
> material reflectance is given for the visible or full solar range. You 
> would have to know (or assume) the properties for UV. For example, a 
> piece of glass with a PVB interlayer might have a 50% transmission in 
> the visible range, but less than 1% transmission in the UV range. Not 
> all materials might have that much variation between visible and UV 
> properties, but you have to be sure that the material properties you 
> use apply to the UV spectrum.
>
> Also consider subtleties of the light source. Different levels of 
> cloud cover probably affect the proportion of UV in the resulting 
> radiation at the earth's surface. Electric light sources might be 
> easier to deal with by converting units.
>
> @Chris: do you mean I should scale my source and material definition by 4?
>
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