The following images show the Cornell University's famous "Cornell Box"
reference scene for 3D rendering...
(1) as a photograph taken from the "real thing" at Cornell University,
using sophisticated calibrated equipment, at a wavelength of 600nm; the
original is an OpenEXR image; I applied linear brightness adjustment for
more contrast and converted to PNG for convenience, which shouldn't hurt
its fitness for serving as a reference image, but if in doubt you can
compare with the original
(http://www.graphics.cornell.edu/online/box/box_exr.zip).
(2) as a POV-Ray 3.7 render using geometry, surface reflectance and
light source data as published by the Cornell University
(http://www.graphics.cornell.edu/online/box/data.html) for a wavelength
of 600nm, using "assumed_gamma 2.2"; light intensity was adjusted in an
attempt to obtain a similar overall brightness as the photograph; notice
how the side walls still appear much too dark while some other areas are
already too bright.
(3) ditto but with gamma-correction applied to the color values; notice
how this fixes the relative brightness of the surfaces, but otherwise
still leaves the image with a much stronger contrast than with the "real
thing".
(4) using the original color values again, but without "assumed_gamma".
The brightness of the light source was adjusted by exactly the same
factor that the photograph had been brightened; no other parameters were
tweaked. Notice how the "real thing" is simulated pretty faithfully.
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Attachments:
Download '600nm.png' (1639 KB)
Download 'cornell_gamma22_raw.png' (95 KB)
Download 'cornell_gamma22_adjusted.png' (112 KB)
Download 'cornell_gamma10.png' (89 KB)
Preview of image '600nm.png'
Preview of image 'cornell_gamma22_raw.png'
Preview of image 'cornell_gamma22_adjusted.png'
Preview of image 'cornell_gamma10.png'
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