Projective alignment with regions

TitleProjective alignment with regions
Publication TypeJournal Articles
Year of Publication2001
AuthorsBasri R, Jacobs DW
JournalPattern Analysis and Machine Intelligence, IEEE Transactions on
Pagination519 - 527
Date Published2001/05//
ISBN Number0162-8828
Keywordsalgebra;object, alignment;projective, approach;segmentation, errors;image, fixed, objects;pose, occlusion;planar, patterns;partial, points;flow, recognition;, recovery;projective, segmentation;matrix, transformations;region-based

We have previously proposed (Basri and Jacobs, 1999, and Jacobs and Basri, 1999) an approach to recognition that uses regions to determine the pose of objects while allowing for partial occlusion of the regions. Regions introduce an attractive alternative to existing global and local approaches, since, unlike global features, they can handle occlusion and segmentation errors, and unlike local features they are not as sensitive to sensor errors, and they are easier to match. The region-based approach also uses image information directly, without the construction of intermediate representations, such as algebraic descriptions, which may be difficult to reliably compute. We further analyze properties of the method for planar objects undergoing projective transformations. In particular, we prove that three visible regions are sufficient to determine the transformation uniquely and that for a large class of objects, two regions are insufficient for this purpose. However, we show that when several regions are available, the pose of the object can generally be recovered even when some or all regions are significantly occluded. Our analysis is based on investigating the flow patterns of points under projective transformations in the presence of fixed points