[Radiance-general] -ar and large scenes

[Greg Ward]

If your outdoor scene is hundreds of times larger than your indoor  
scene, you are probably better off setting -ar 0 and just suffering  
the long render times in the inside corners.  If the bounding cube is  
less than a hundred times larger than your interior space, then just  
increase your -ar setting by the corresponding factor, or let rad  
figure it out for you.

-Greg

> From: Rob Guglielmetti <rpg at rumblestrip.org>
> Date: November 18, 2005 3:19:58 PM PST
>
> Howdy folks.
>
> Been playing with the new "drape" command in AutoCAD 2006.  This  
> command makes it extremely easy to create terrain meshes, and I'm  
> working on a project that is located in a valley so I thought it'd  
> be nice to be able to model the valley since the mountains provide  
> some considerable shading in the morning and afternoons.  But of  
> course now my octree bounding box is quite large, which leads me to  
> this ditty from the rtrace manpage, regarding the -ar parameter:
>
> *"*The maximum  ambient  value  density  is the scene size times  
> the ambient accuracy (see the /-aa/ option below)  divided  by  the  
> ambient  resolution."
>
> By having such an expansive outdoor geometry, am I forcing a very  
> high -ar in order to get good data from rtraces in an interior  
> space, or if I use enough -ab will this not matter?  A test render  
> looked very flat too; I thought it was the mellow settings I used  
> for the test render, but now I'm concerned that without -ar's in  
> the thousands (!), my renderings will always look very flat.
> - Rob Guglielmetti
>