[Radiance-general] mkillum illuminating outside?

[Jack de Valpine]

Hi Lars,

One thing that we do to confirm orientation is to test the relevant 
geometry by assigning a glow material. Front will "glow" back will be black.

-Jack

Greg Ward wrote:
> Hi Lars,
>
> Nice that I slept through this one, too...  Your debugging tips are 
> helpful.  Another way to determine whether you are looking at the back 
> or front of a surface is in rvu, which reports the first surface hit 
> (even if it's invisible) and tells you back or front.  This is only 
> for materials that care which side you hit, like lights, illums, 
> dielectric, etc.  Plastic and metal won't let you know.  The only way 
> to tell for these surfaces is to turn backface visibility off with 
> -bv0.  This can cause your scene to look a bit confused, so I only 
> recommend it as a last resort.
>
> Best,
> -Greg
>
>> From: "Lars O. Grobe" <akilog at nus.edu.sg>
>> Date: February 11, 2009 3:30:18 AM PST
>>
>> Sorry, this was a stupid mistake of mine. When I replaced the polygon 
>> surface that I had been using before by a !gensurf-line, I ended up 
>> with a wrong surface normal. This made my illum become oriented to 
>> the outside world. As the other surfaces where still facing inwards, 
>> the culprit surface still got enough light from the sides to 
>> illuminate the opposite wall. I only found this when I switched to 
>> the light modifier type using mkillums l+, because than the surface 
>> appeared completely black when seen from inside (the illum being not 
>> visible itself makes this kind of debugging more difficult, and I was 
>> 100% sure that the orientation was ok because I had tested it before 
>> - but than there had been the polygon).
>>
>> So, this is my second non-problem reported to the list, sorry for 
>> messing up your mail boxes...
>>
>> CU Lars.
>
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