[Radiance-general] computing illuminance across a grid

[Rob Guglielmetti]

On 23 May 2002, at 11:35, I wrote:

> Also, I'm wondering how rtrace gets its information, since
> it's working with an octree, not a pic file.  I don't
> understand how it can compute irradiance so fast unless it
> somehow works with a pic file and/or the cached ambient
> file.  Along those lines, if you want accurate values for a
> room, and only have generated a pic of, say, the north
> elevation, how accurate are the vertical illuminance values
> on the south elevation?  

And then later I wrote:

> > Some more info:
> >
> > I just did a falsecolor image of my scene and it too 
shows
> > a totally dark room, with a single patch of direct sun. 
> > The rest of the space is < 1Lux.

To which Schorsch replied:

> That's a pretty safe indicator for the -ab 0 syndrome...

Which I suppose is one way of saying RTFM.  Sorry gang.  
Now I see that rtrace needs to be told what to do just 
like rpict, in terms of the myriad switches.  Sigh.  I guess 
coming from the Lightscape/radiosity world I still can't 
shake the idea that once you wait a while for a calc, all 
the data is there for the asking.  

Is there a way to somehow tell rad to do some rtrace 
stuff and have rad control the options based on a .rif file, 
in the manner that rad controls rpict?

         ====================
 Rob Guglielmetti <rpg777@earthlink.net>
    http://home.earthlink.net/~rpg777