[Radiance-general] -ar, -ad, -as, ahh $#*@!

[Rob Guglielmetti]

thanks everyone!

Mark, just for fun, I'm trying your -aa 0 -ad 16 trick right now (it'll 
be a while before I can post a result, methinks).

Martin, yours was a good heads up as to the essence of the problem -- 
once again I'm expecting brute force CPU cycles to make up for a lack of 
understanding about the guts of Radiance.

This is good, though.  I finally realize that mkillum can be thought of 
as a way of rolling your own ies files, sorta.

Greg Ward wrote:

> Hi Rob,
> 
> This seems to be a classic example of where you just can't rely on the 
> interreflection calculation in Radiance to solve your problem for you.  
> The basic assumption in this approximation is that the indirect 
> illumination varies slowly over surfaces, which clearly isn't the case 
> in this scene.

er, right.  =8-/

> Solution: you need to apply mkillum to create pseudo light sources 
> (imposters) for your indirect luminaires.  To do so, put a shallow box 
> with an open top around a single ceiling-mounted light source (5 
> rectangles) and use the "void" modifer for these, making sure they face 
> out into your room.  Let's say you called this file "light_in.rad".  
> Using either the octree for your room or a reduced one that just has 
> that one light source switched on (better), you would run mkillum thus:

lemme make sure I understand; these 5 rectangles would define the inside 
recess of the coffer, yes?  And I would call it out like so:

void polygon coffer.top
0
0
12
	0 0 -5
	0 10 -5
	10 10 -5
	10 0 -5

... and so on?

For the
> sake of calculational efficiency, I recommend that you also change the 
> light primitives in your original luminaire files to the "glow" type 
> with an effective distance equal to the diagonal of your luminaire 
> dimension, so as to avoid sending shadow rays to these sources 
> unnecessarily.

I *think* I understand...

> The net result should be a fast and accurate rendering of your space.

That's all I ever wanted. =8-)

I'll try these suggestions. Thanks guys.

----

      Rob Guglielmetti

e. rpg@rumblestrip.org
w. www.rumblestrip.org