clipka <ano### [at] anonymousorg> wrote:
> Am 27.05.2011 00:15, schrieb Crippso:
> > Hi,
> >
> > I've only just downloaded pov-ray so sorry if this is a really stupid
> > question...
> >
> > I understand that the camera model in pov-ray is that of an ideal pin hole
> > camera, and that the field of view of the camera is set which essentially
> > defines the properties of the 'lens' in front of the camera.
> >
> > What I'd really like to be able to do is model what a focal plane array (FPA)
> > would see when a camera has no lens to focus the rays. In this 'no-lens'
> > scenario I'd like to define an approximate field of view by placing the FPA at
> > the back face of a cylinder, with an aperture in the front face.
> >
> > Is this possible in pov-ray?
>
> Possibly the most realistic way to model this would be as follows:
>
> - Build your "camera" using scene geometry, including a placeholder
> dummy for the FPA, which should be a plain white diffuse slab (pigment {
> rgb 1.0 } finish { ambient 0 diffuse 1.0 specular 0 }).
>
> - Turn on radiosity (you may need very high-quality settings, especially
> a high "count" value). This will effectively project the scene onto the
> FPA dummy slab (very blurry).
>
> - Use an orthographic camera placed just a tiny bit in front of the FPA
> dummy, oriented to look at the FPA dummy, to capture the pattern of
> light projected onto the dummy. (Note that you may actually get a
> mirrored image.)

Thanks, thats very helpful. I've given it a try and am getting some good results
by playing around with the radiosity settings.

I'd like to place a flat disc in front of my FPA that is acting as a lambertian
emitter. The FPA will see part of this emitter through the aperture in the
cylinder. Is it possible to include such surfaces in povray by setting their
ambient value to a number representing the radiance of the surface?

Much advice on radiosity suggests ambient should always be set to zero so I
wasn't sure if using ambient was a good way of generating a lambertian emitter
when using radiosity.

Ultimately I would like to be able to use the pixel values I obtain when looking
at the diffuse slab that represents the FPA and convert these to Watts (or
photons per second) based on the amount of light emission from the flat disc.
Any advice on the best way to acheive this would be very helpful too (I have
already set gamma to 1.0)

Thanks
Stuart

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