Capture and Simulation of Fluorescence in Fabrics Estimating and simulating fluorescent appearance in fabrics using LEDs and an RGB camera.
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Examensarbete för masterexamen
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In textiles, fluorophores (fluorescent molecules) are mixed with dyes to help achieve
exceptionally vivid colours. Fluorophores help achieve such bright colours by absorbing
light with a short wavelength (such as hard to see ultra-violet) and re-emit
light with a longer wavelength (such as a blue, orange or red). The challenge when
simulating fluorescence is that it places demands on the rendering-system (the system
that simulates light interactions with the materials). An additional challenge
is that methods to capture this fluorescent behaviour require specialised laboratory
equipment. In this thesis, experiments are presented that aim to study if the multiple
levels of structure in fabrics introduce any angular dependence of the fluorescence.
The results suggest that in fluorescent yarns and fabrics there is no significant angular
dependence. This result indicates that fluorescence can be captured from a
flat sample from any distance, and that yarn-level resolution is not required in this
regard. Using those conclusions a practical capture setup for fluorescence in fabrics
is proposed. The method uses nine narrow-band LEDs, a consumer camera and
an image analysis procedure that estimates the wavelengths of the detected light
through numerical optimisation to give a re-radiance matrix. This matrix describes
the fluorescent material’s spectral response to wavelengths of incomming light. The
results using this capture setup are compared against raw data measured with a
spectrometer. The results show agreement. Finally, matrices acquired from the
capture setup are used to generate computer generated images of the materials under
different illuminations. These images are compared to photographs of the same
scenes.
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computer graphics, spectral rendering, fluorescence, appearance capture, material modelling