Four Light Total Appearance Imaging of Paintings. Berns 00000Paper abstract bibtex The total appearance of a painting is defined by its spatially varying spectral reflectance factor, surface macrostructure (depth or surface normal), and surface microstructure (bi-directional reflectance distribution function, BRDF). For paintings with uniform BRDF (e.g., varnished), their total appearance can be measured using equipment commonly found in a photographic studio. Such a system was built and tested for several acrylic- dispersion paintings. The system consisted of three or four strobes affixed with triacetate film lin ear polarizers and a Dual-RGB camera also affixed with a linear polarizer in order to achieve cross polarization. Using the principles of photometric stereo, images of each light source taken sequentially from 45° from the normal and 90° apart annularly (four lights) or 30° from the normal and 120° apart annularly (three lights) were used to measure surface normal. A learning-based algorithm was used to measure colorimetry and spectral reflectance factor. Software, Artviewer , was written to render images for specific geometries and for studio lighting. The system produced images that approximated, but not equaled, conventional studio photography. Because diffuse data were collected, these images are useful for the long-term evaluation of color changes. Evaluation of the surface normal provides new information for the technical examination of artwork.
@misc{berns_four_nodate,
title = {Four {Light} {Total} {Appearance} {Imaging} of {Paintings}},
url = {http://www.cis.rit.edu/DocumentLibrary/admin/uploads/CIS000127.pdf},
abstract = {The total appearance of a painting is defined by its spatially
varying spectral reflectance factor, surface macrostructure (depth
or surface normal), and surface microstructure (bi-directional
reflectance distribution function,
BRDF). For paintings with
uniform BRDF (e.g., varnished), their total appearance can be
measured using equipment commonly found in a photographic
studio. Such a system was built and tested for several acrylic-
dispersion paintings. The system consisted of three or four strobes
affixed with triacetate film lin
ear polarizers and a Dual-RGB
camera also affixed with a linear polarizer in order to achieve
cross polarization. Using the principles of photometric stereo,
images of each light source taken sequentially from 45° from the
normal and 90° apart annularly (four lights) or 30° from the
normal and 120° apart annularly (three lights) were used to
measure surface normal. A learning-based algorithm was used to
measure colorimetry and spectral reflectance factor. Software,
Artviewer
, was written to render images for specific geometries
and for studio lighting. The system produced images that
approximated, but not equaled, conventional studio photography.
Because diffuse data were collected, these images are useful for
the long-term evaluation of color changes. Evaluation of the
surface normal provides new information for the technical
examination of artwork.},
urldate = {2017-02-08TZ},
author = {Berns},
note = {00000},
keywords = {appearance}
}
Downloads: 0
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