Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Calibration, recognition, and shape from silhouettes of stones
Includes bibliographical references (p. 229-239).
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Electrical Engineering
2014
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613182747475968 |
|---|---|
| access_status_str | Open Access |
| author | Forbes, Keith |
| author2 | Nicolls, Fred |
| author_browse | Forbes, Keith Nicolls, Fred |
| author_facet | Nicolls, Fred Forbes, Keith |
| author_sort | Forbes, Keith |
| collection | Thesis |
| description | Includes bibliographical references (p. 229-239). |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/8903 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:05.102Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | Department of Electrical Engineering |
| publisherStr | Department of Electrical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/8903 Calibration, recognition, and shape from silhouettes of stones Forbes, Keith Nicolls, Fred De Jager, Gerhard Electrical Engineering Includes bibliographical references (p. 229-239). Multi-view shape-from-silhouette systems are increasingly used for analysing stones. This thesis presents methods to estimate stone shape and to recognise individual stones from their silhouettes. Calibration of two image capture setups is investigated. First, a setup consisting of two mirrors and a camera is introduced. Pose and camera internal parameters are inferred from silhouettes alone. Second. the configuration and calibration of a high throughput multi-camera setup is covered. Multiple silhouette sets of a stone are merged into a single set by inferring relative poses between sets. This is achieved by adjusting pose parameters to maximise geometrical consistency specified by the epipolar tangency constraint. Shape properties (such as volume, flatness, and eiongation) are inferred more accurately from the merged silhouette sets than from the original silhouette sets. Merging is used to recognise individual stones from pairs of silhouette sets captured on different occasions. Merged sets with sufficient geometrical consistency are classified as matches (produced by the same stone), whereas inconsistent sets are classified as mismatches. Batch matching is determining the one-to-one correspondence between two unordered batches of silhouette sets of the same batch of stones. A probabilistic framework is used to combine recognition by merging (which is slow, but accurate) with the efficiency of computing shape distribution-based dissimilarity values. Two unordered batches of 1200 six-view silhouette sets of uncut gemstones are correctly matched in approximately 68 seconds (using a 3.2 GHz Pentium 4 machine]. An experiment that compares silhouette-based shape estimates with mechanical sieving demonstrates an application using the developed methods. A batch of 494 garnets is sieved 15 times. After each sieving, silhouette sets are captured for sub-batches in each bin. Batch matching is used to determine the IS sieve bins per stone. Better estimates of repeatability, and better understanding of the variability of the sieving process is obtained than if only histograms (the natural output of sieving) were considered. Silhouette-based sieve emulation is found to be more repeatable than mechanical sieving. 2014-10-29T10:01:34Z 2014-10-29T10:01:34Z 2007 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/8903 eng application/pdf Department of Electrical Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Electrical Engineering Forbes, Keith Calibration, recognition, and shape from silhouettes of stones |
| thesis_degree_str | Doctoral |
| title | Calibration, recognition, and shape from silhouettes of stones |
| title_full | Calibration, recognition, and shape from silhouettes of stones |
| title_fullStr | Calibration, recognition, and shape from silhouettes of stones |
| title_full_unstemmed | Calibration, recognition, and shape from silhouettes of stones |
| title_short | Calibration, recognition, and shape from silhouettes of stones |
| title_sort | calibration recognition and shape from silhouettes of stones |
| topic | Electrical Engineering |
| url | http://hdl.handle.net/11427/8903 |
| work_keys_str_mv | AT forbeskeith calibrationrecognitionandshapefromsilhouettesofstones |