"clipka" <nomail@nomail> wrote:
> "Colin" <nomail@nomail> wrote:
> > I'd like to use POV-Ray to evaluate light positioning and reflector design, and
> > thus would like to be able to map relative light intensities on a flat surface.
> > How might this be accomplished?
>
> I'm not quite sure whether I understand what you mean.
>
> What comes to my mind is designing a car headlight, and an attempt to simulate
> the pattern of light (a) created on a wall at a distance of whatsoever meters,
> and/or (b) the pattern of light created on the road.
>
> Does this come close to what you intend to do?
>
>
> If that is what you're doing, I guess you're looking for is...
>
> (1) PoV-ray's "ortographic camera", which allows you to render any surface
> without perspective distortion;
>
> (2) PoV-ray's "photon mapping" feature, which does forward raytracing (i.e.
> shooting light rays from a light source) and is specially designed to simulate
> lighting effects involving light being reflecting and/or refracted
> ("caustics").

So what I'm looking for is if you were tracing photons, how many per unit area
strikes a particular position on a surface. We usually measure this in things
like W/m2 or lux (lumens/m2).

So, say for example I put a point
light source above a flat surface. If I render it, I see that it's brightest
directly below the source. At a point some distance away from this centerline,
it is dimmer. What I would like is a metric for how much dimmer it is, as a
function of position. I assume this would be trivial from within the
ray-tracing algorithm; I'm just curious if it's possible from the user end.

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