Oscillation of the Measurement Accuracy of the Center Location of an Ellipse on a Digital Image
Circular targets are often utilized in photogrammetry and a circle on a plane is projected as an ellipse onto an oblique image. This paper reports an experiment conducted to investigate whether the measurement accuracy of the center location of an ellipse on a digital image oscillates as its dimensi...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-08-01
|
| Series: | The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-3/211/2014/isprsarchives-XL-3-211-2014.pdf |
| Summary: | Circular targets are often utilized in photogrammetry and a circle on a plane is projected as an ellipse onto an oblique image. This
paper reports an experiment conducted to investigate whether the measurement accuracy of the center location of an ellipse on a
digital image oscillates as its dimension increases. The experiment was executed by the Monte Carlo simulation using 1024
synthesized images of which the centers were randomly distributed in one pixel for each ellipse. We investigated four typical
measurement methods: intensity-weighted centroid method, non-iterative ellipse fitting, iterative ellipse fitting with the star operator,
and least-squares matching. Three flattenings 0.00, 0.25, 0.50, and three rotation angles 0.0°, 22.5°, 45.0° were investigated in the
experiment. The experiment results clearly show that the measurement accuracy by all the investigated methods would oscillate as
the dimension of an ellipse increases. The measurement accuracy by the intensity-weighted centroid method and the non-iterative
ellipse fitting would oscillate smoothly, while that by the least-squares matching would oscillate considerably roughly. It would be
impossible to determine the cycle of the oscillation except the measurement accuracy by the intensity-weighted centroid method and
the non-iterative ellipse fitting when the rotation angle of an ellipse is 0.0° and 45.0°. The experiment results indicate that the
flattening and the rotation angle of an ellipse would affect the cycle of the oscillation as well. |
|---|---|
| ISSN: | 1682-1750 2194-9034 |