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Three participating fluorescent bodies illuminated by ultra violet light.
A relative spectral emission functions is used to make a linear shift in the wavelenghts
which makes the bodies re-emit blue, yellow and red light.
Note that the fluorescent objects do not block the light coming from
the ceiling (cast shadow) because it is actually the only visible lightsource
in the scene. This is, of course, due to the re-emission of
energy from the ultra violet band.
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Abstract
The present paper concerns two independent parts. In the first
part of this project a modification to the radiative transfer equation,
which takes the effects of fluorescence into account, is formulated.
The derivation is based on the law of Beer-Lambert-Bouguer and
the resulting modification can be seen as an extension to the inscattering
term which creates a dependence between every wavelength.
The way of introducing terms that models fluorescence has
in previous work been a straightforward process without further argumentation.
The theory introduced here differ from previous work
in the way of derivation and argumentation. A method on how to
model the result using the method of photon mapping [Jensen 2001]
is proposed and illustrated using an implemented spectral render.
The case of phosphorescence is not considered, but the theory proposed
can be used to some extent.
In the second part a method for evaluating the radiance estimate,
used in the photon mapping technique, is proposed. This method is
built upon the strength of Fourier series and was originally intended
to be used as an optimization tool to render the results in the first
part of the paper. The introduction of the series eliminates the need
of photon maps for rendering and enables minimal space requirements
for representing the flux density. It also replaces the kd-tree
search, which in turn enables the series to be easily implemented
on graphical hardware even though this paper does not target this.
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