[Radiance-general] falsecolor and specific isocontours

[Gregory J. Ward]

Hi Chris,

No, falsecolor doesn't offer such an option.  However, you can do it 
yourself with pcomb:

	pcomb -e 'incontr=eq(we*li(1),16.5,0.25)' \
		-e 'ro=if(incontr,0,ri(1)' \
		-e 'go=if(incontr,1,gi(1)' \
		-e 'bo=if(incontr,0,bi(1)' \
		-e 'and(a,b):if(a,b,a)' \
		-e 'eq(a,b,eps):and(a-b+eps,b-a+eps)' \
		-o input.pic > contoured.pic

This assumes you meant 16.5 lux or nits (depending on whether 
"input.pic" was rendered with the -i option or not).  If you meant 16.5 
watts/sr/m^2, then take out the "we*" in the first expression.  I also 
used an epsilon of 0.25 about 16.5, so anything between 16.25 and 16.75 
will be colored green.  If you want some other range, you can adjust 
this.  If you want a perfectly sharp line, then you'll need to use the 
more sophisticated pcomb script within falsecolor, which I won't 
reproduce here.  Other options, such as placing a contour over a 
tone-mapped (pcond output) image are easily accommodated by altering 
the command above.

-Greg

> From: Christopher Kings-Lynne <chriskl at familyhealth.com.au>
> Date: February 3, 2005 3:10:37 AM PST
>
> Hi,
>
> Is there any way to tell falsecolor to draw contours at specific 
> isolevels, instead of its automatic method?
>
> ie. If I just wanted a contour at level 16.5 and that's all...
>
> Thanks,
>
> Chris