[Radiance-general] using rpict like a range scanner

[Greg Ward]

Another caveat -- the -z output from rpict is the "effective ray 
length," not the distance to first intersection.  This means that for 
glass or mirror surfaces, it may be the distance to the object seen 
through the glass or mirror rather than the distance to the glass or 
mirror surface itself.

If you really want the first object intersection distance, regardless 
of material type, you should use the vwrays command together with 
rtrace and the -oL option.

-Greg

> From: Peter Apian-Bennewitz <apian at pab-opto.de>
> Date: September 13, 2004 10:42:00 AM PDT
>
> Greg Ward wrote:
>
>>> From: Tarik Rahman <tarik.rahman at ed.ac.uk>
>>> Date: September 13, 2004 8:13:36 AM PDT
>>>
>>> Hi
>>> When using rpict -z to get pixel distances, are these distances the 
>>> distance
>>> from viewpoint until it hits the first object, just like a laser 
>>> range scanner?
>>
>>
>> Yes, unless you have assigned a fore clipping plane (-vo option), in 
>> which case it is the distance from this plane (which may be a 
>> cylinder or a sphere for the -vtc, -vta and -vth options).
>>
>> -Greg