[Radiance-general] Re: physically-based landscapes

[Greg Ward]

Hi Santiago,

> From: "Santiago Torres" <tiago@tkh.att.ne.jp>
>
> I`ve been trying more, and the mapping now works fine, so the sky 
> finally
> looks like the original picture. However, I still have problems with 
> the
> illuminance values. I am defining it like this:
>
> void colorpict skyfunc
> 7 noop noop noop sky_orig.pic fisheye.cal fish_u fish_v -rx 90 -rz 180
> 0
> 1 1

What is the last real argument (A1=1) for?  I think fisheye.cal just 
ignores it.

> And then using skyfunc normally, like from gensky. The "mapped" sky 
> gives me
> an illuminance 5 to 7 times lower than the original sky (although the
> distribution is the same). I could define the sky source seven times
> stronger to compensate, but I`m sure there must be an explanation for 
> this
> and a correct solution. Please, what am I doing wrong?

What is in sky_orig.pic?  Is it possible that you exposed it with pfilt 
or something -- you need to have the original values in there.  The 
direct output of rpict should work, but passing it through pfilt would 
not.

> Another problem is when I apply the sky to a scene with a room and a 
> window.
> If I follow Greg`s method to define the window, it works perfect, 
> however if
> I use the mapping to define a sky and then define a window as I would 
> do
> with a "gensky`d" sky, there seems to be no direct sunlight in the 
> room.
> Again, what am I doing wrong?

Gensky creates a separate source for the sun, whereas it gets included 
as a small spot in sky_orig.pic, which the indirect calculation is 
hard-pressed to find.  To get it to work as gensky, you would have to 
take the solar source from gensky and reapply it in your model.

-Greg