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

[Greg Ward]

Hi Lucio,

I'm glad that the basic idea works.  The command I sent you does  
literally what you asked, which is to show the luminance in the  
direction of the desired point.  As you noticed, the ray does not  
necessarily get there.  To ensure that it does, you could simply  
start the ray closer to the target point by replacing the rcalc  
command with:

	rcalc -if3 -of -e '$1=$1-nrm*Dx;$2=$2-nrm*Dy;$3=$3-nrm*Dz;$4=Dx; 
$5=Dy;$6=Dz' \
			-e 'Dx=$1-OX;Dy=$2-OY;Dz=$3-OZ;nrm=0.001/sqrt(Dx*Dx+Dy*Dy+Dz*Dz)'

What this does is start each ray a short distance (0.001 in world  
units) from the target point, ensuring that no intervening geometry  
obstructs the view.

I hope this helps.
-Greg

> From: "loscotec\@libero\.it" <loscotec at libero.it>
> Date: February 8, 2008 5:26:38 AM PST
>
> I finally tried the isolux plot from a different view as you  
> suggested me, Greg .
>
> Thank you very very very much for your help !
>
> it does wark properly and I did not even had to correct formula  
> "wrays.." as it was already correct !
>
> I tried aslo the pinterp strategy, but, having my observer a very  
> small angle of view on the street, the requested resolution of the  
> first image would have been far to big.
>
> I figured out that the vwrays method does not work correctly if  
> there are some obstructions between observer and calculated point .  
> As I'm feeding rtrace view view directions.. !
>
> Is there a stratagem to control this in some way? I dont really  
> need it right now, but i could in the future and I'm really  
> interested in trying to build up some solid calculation program.. !
>
> Thank you very much again !
>
> Lucio