[Radiance-general] Sky component only

[nick devlin]

Thomas,

I used mkillum yesterday and bingo!!! got some better results, that I am  
trying to validate.
One question though, I just need to be certain that there is no ambient  
light in my results.

so to check, I am using the following for mkillum and then rtrace:

mkillum -I -h -dp 2046 -ar 32 -ms 0.063 -ds .2 -dt .05 -dc .75 -dr 3 -sj 1  
-st .01 -ab 0 -aa .1 -ad 512 -as 256 -av 0 0 0 -lr 12 -lw .0005 -af  
scene2.amb scene2.oct < window.rad > mkwin2.rad

rtrace -I -h -dp 2046 -ar 32 -ms 0.063 -ds .2 -dt .05 -dc .75 -dr 3 -sj 1  
-st .01 -ae Zero_Ref -ab 0 -aa .1 -ad 512 -as 256 -av 0 0 0 -lr 12 -lw  
.0005 -af scene2.amb mkscene2.oct < mk1.pts > existing3.dat

I assume that by setting -ab 0 and -av 0 0 0 there should be no ambient  
calculation, and indeed, lookamb just returns the values from rtrace,  
rather than a data file for value, position etc.. I believe this is a good  
thing.

Your thoughts would be greatly apprecicated however.

many thanks

nick


On 22.09.2005, at 13:19, nick devlin wrote:

> Thomas,
>  thanks for that. I had tried it in the past but rtrace returns
> values of zero!!
>  I was confused about this, until I remember that for a uniform, or  
> overcast sky (the types I am testing), the sky is a glow source, which I  
> believe is not tested in the direct calculation.
> which means I am back to the drawing board.

You could probably replace your windows with illums
using mkillum and a higher -ab value. For your final
rtrace calculations you can use -ab 0 again and only
get the "direct" contribution of the window illum.

I have to admit that I don't know what causes your
problems and therefore this approche may fail as well.


Thomas