[Radiance-general] Re: falsecolor's isolux on observer's luminance.

[Greg Ward]

Hi Lucio,

Yes, it is true that pinterp needs to fill in missing pixel values,  
which is why you need a very high resolution image.  (In fact, it  
would make sense to set the vertical resolution higher than the  
horizontal resolution, with the -pa 0 option to allow non-square  
pixels.)  However, the results should still be valid.

If you are concerned about calculation efficiency, then you could  
write a script as you suggest.  First, you would use vwrays to feed  
rtrace and get it to generate intersection points for all the  
positions on the orthogonal view.  Second, you would apply a script  
to convert these positions to directions from the observer for a  
second rtrace run that would compute your radiance values.  This  
would be output to an image.  I guess it would go something like:

% vwrays -ff -vf ortho.vf -x XRES -y YRES -pa 0 \
	| rtrace -h -ff -op roadway.oct \
	| rcalc -if3 -of -e '$1=OX;$2=OY;$3=OZ;$4=$1-OX;$5=$2-OY;$6=$3-OZ' \
	| rtrace -ffc -x XRES -y YRES roadway.oct \
	| falsecolor -cl -s auto \
	| ra_tiff - roadway_lum.tif

where XRES and YRES are the desired map resolution and OX, OY, and OZ  
are the observer coordinates.  (E.g., add -e 'OX:10.5;OY:-3.9;OZ=2'  
to the rcalc line.)

I hope this makes sense.  It may require some adjustments -- I didn't  
test it out!

-Greg

> From: "loscotec\@libero\.it" <loscotec at libero.it>
> Date: February 4, 2008 9:39:02 AM PST
>
> Wonderfull!!!
>
> So powerfull is Radiance!! :o)
>
> That's really what I wanted ! Thank you very much !!!
>
> Now let's see if I'm able to really do it ! :-P
>
> Just a curiosity. Pinterp just interpolates datas, right? So as  
> much going far from the observer, as loosing detail, isn't it? This  
> is probably the reason why I need high resolution image.
>
> It is not possible to just calculate the points needed for the last  
> image orthogonal one) from the observer point of view , and save  
> results in an image format? It would probably need just a quite  
> simple script (which calls rtrace many times) and could save much  
> render time (definition is only were needed). Am I right? Or there  
> is something I didn't contemplate?
>
> Lucio
>