[Radiance-general] Plotting specific points

[Greg Ward]

Hi Chris,

Unfortunately, there is no program that will do what you want directly, 
as it would be an easy thing to do.  The only way I could figure out to 
do this without writing a very nasty pcomb script is a hack involving 
vwrays and glow sources in rpict.  For a 1024x768 image, it would go 
something like this:

% echo void glow sglow 0 0 4 100 0 0 0 > sources.rad
% vwrays -i orig.pic < image.pts | rcalc -o 'sglow source s${recno} 0 0 
4 ${$4} ${$5} ${$6} 2' >> sources.rad
% oconv sources.rad | rpict -vf orig.pic -w -x 1024 -y 768 \
	| pcompos orig.pic 0 0 -t 1 - 0 0 > spotty.pic
% rm sources.rad

The file "orig.pic" is your original rendering, and "image.pts" is a 
set of x and y picture coordinates (x left to right, y bottom to top) 
giving positions in this image where you want to place red spots.  
(Change the echo command if you want a different color.)  The vwrays 
then generates rays to each point in the image, which get converted to 
2-degree distant sources by the rcalc command.  (Again, you may wish to 
alter this if 2 is too big or too small.)  Finally, we render these 
sources and superimpose them on the original picture using rpict and 
pcompos (with a threshold), resulting in "spotty.pic".

I haven't tried this, and I probably messed up some bit of it, but 
hopefully you'll be able to sort it out.

-Greg

> From: Christopher Kings-Lynne <chriskl at familyhealth.com.au>
> Date: February 16, 2005 5:59:08 AM PST
>
> Hmmm, does anyone know the best/easiest way to take a file of x and y 
> coordinates of dots, and draw those dots on a .pic?
>
> Chris