The principle aim of this study was to use the concept of image defocus related to feature depth in order to develop a system capable of converting a 2-dimensional greyscale image into a 3-dimensional depth map. An advantage of this concept (known as depth-from-defocus or simply DfD) over techniques such as stereo imaging is that there is no so-called ‘correspondence problem’ where the corresponding location of a feature or landmark point must be identified in each of the stereo images. The majority – and the most successful – of previous researchers in DfD have used some variation of a ‘two-image’ technique in order to separate the contribution of the original scene features from the defocus effect. The best of those have achieved results typically in the range of 1% to 2% error in the accuracy of depth estimation. This thesis presents a single-image method of generating a high-density, highaccuracy depth map via the evaluation of the edge profiles of a projected structured light pattern. A novel technique of moving the projected pattern during the image capture stage allows the development of a 4-dimensional look-up table. This technique offers a solution to one of the last remaining problems in DfD, that of spatial variance. It also uses a technique to remove the dependence of original scene reflectance. The final solution generates a depth map of up to 240,000 spatially invariant depth estimates per scene image, with an accuracy of within ± 0.5%, over a depth range of 10 cm. The depth map is generated in a processing time of approximately 14 seconds once the images are loaded.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:490400 |
| Date | January 2007 |
| Creators | Crofts, William Edward |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/65288/ |
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