- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Multiple light source optical flow for translations...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Multiple light source optical flow for translations and rotations in the image plane Takagi, Shingo Jason
Abstract
The classic optical flow constraint equation is accurate under conditions of translation and distant light sources, but becomes inaccurate under conditions where the object may rotate or deform. The inaccuracies are generally a result of the changing intensities at points under rotation or deformation. The changing intensities of these points are associated with the changing surface gradients. We investigate a novel approach to multiple light source optical flow under known reflectance properties. This novel approach is specialized for translation and for rotation around axes which are parallel to the optical axis. The assumption that the object is moving under translation, rotation, or a combination of translation androtation in the image plane allows us to introduce a physical surface area constraint. Even with this additional constraint, however, the problem still remains locally underdetermined. At each time frame, our multiple light source optical flow approach assumes that three images are acquired from the same viewpoint, but under three different illumination conditions. Photometric stereo determines many of the coefficients in our underdetermined system, which has six equations in seven unknowns at each pixel in the image. Two of the unknowns are the optical flow components. Another three of the unknowns are the total derivatives of the three intensities with respect to time. The last two are the total derivatives of the surface gradients with respect to time. A variety of local regularization methods were investigated to select optical flow estimates which best matched the known motion fields. All the experimental results for this approach were obtained from synthetic data, in which the motion fields were known.
Item Metadata
Title |
Multiple light source optical flow for translations and rotations in the image plane
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2001
|
Description |
The classic optical flow constraint equation is accurate under conditions of
translation and distant light sources, but becomes inaccurate under conditions where the
object may rotate or deform. The inaccuracies are generally a result of the changing
intensities at points under rotation or deformation. The changing intensities of these
points are associated with the changing surface gradients. We investigate a novel
approach to multiple light source optical flow under known reflectance properties. This
novel approach is specialized for translation and for rotation around axes which are
parallel to the optical axis. The assumption that the object is moving under translation,
rotation, or a combination of translation androtation in the image plane allows us to
introduce a physical surface area constraint. Even with this additional constraint,
however, the problem still remains locally underdetermined.
At each time frame, our multiple light source optical flow approach assumes that
three images are acquired from the same viewpoint, but under three different illumination
conditions. Photometric stereo determines many of the coefficients in our
underdetermined system, which has six equations in seven unknowns at each pixel in the
image. Two of the unknowns are the optical flow components. Another three of the
unknowns are the total derivatives of the three intensities with respect to time. The last
two are the total derivatives of the surface gradients with respect to time. A variety of
local regularization methods were investigated to select optical flow estimates which best
matched the known motion fields. All the experimental results for this approach were
obtained from synthetic data, in which the motion fields were known.
|
Extent |
11950220 bytes
|
Genre | |
Type | |
File Format |
application/pdf
|
Language |
eng
|
Date Available |
2009-07-29
|
Provider |
Vancouver : University of British Columbia Library
|
Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
|
DOI |
10.14288/1.0051694
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Graduation Date |
2001-05
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.