[Radiance-general] computing illuminance across a grid

[Georg Mischler]

> > 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.

I really hate this damned machine,
I wish that I could sell it.
It never does quite what I want,
But only what I tell it.


Ok, I admit that the default parameters of the various Radiance
programs are not designed to give you a first "nice looking"
result without any tweaking. Which is probably a healthy fact
to get bumped against right before the first illusions of
perfection can kick in... ;)


> 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?

You can run a "rad -n" on the rif, and copy the relevant parts of
the output to a file. Then use the @<file> parameter with rtrace.
In fact, it often is a good idea to run a small picture before the
rtrace, to more thoroughly initialize the ambient file. The few
dozen initial rays from your grid may not cause the altorithm to
look at all corners of your space in sufficient density, which can
result in somewhat erratic or even lopsided output values.


-schorsch

-- 
Georg Mischler  --  simulations developer  --  schorsch at schorsch.com
+schorsch.com+  --  lighting design tools  --  http://www.schorsch.com/