Not really.  The separation keyword allows you to specify the spacial
separation of photons at the center of the target object.  Of course,
photons are always spreading out (from the light source location) so the
actual spacing is always increasing as the photon moves farther from the
light source (unless it gets focused by a lens, of course).

I could have made the user specify an angular spacing (or a total number of
photons, for that matter) instead of a spacial separation.  I chose
spacial separation because it correlates directly with the size of the
gather radius (which the user must also specify).  Thus, once you have
the settings figured out for a scene, you can scale the separation
values and gather radius by the same amount to increase/decrease the
total number of photons.

As you move the light source closer and farther from the target object,
the angular density of the photons will change, but the total number of
photons will remain approximately the same.

-Nathan Kopp

Bob wrote:
> 
> Think I'll stick to rendering only. No programming math for me, thankyou.
> But back to the question about light source distance :) is it directly proportional
to
> the "separation" then? In other words, the closer or farther away a light, a
narrower or
> wider separation is needed to keep the same end result?
>

Post a reply to this message