Efficient Model Library Access by Projectively Invariant Indexing Functions

Projectively invariant shape descriptors allow fast indexing into model libraries without the need for pose computation or camera calibration. This paper describes progress in building a model based vision system for plane objects that uses algebraic projective invariants. We give a brief account of these descriptors and then describe the recognition system, giving examples of the invariant techniques working on real images

Digital Image Access & Retrieval

The 33th Annual Clinic on Library Applications of Data Processing, held at the University of Illinois at Urbana-Champaign in March of 1996, addressed the theme of "Digital Image Access & Retrieval." The papers from this conference cover a wide range of topics concerning digital imaging technology for visual resource collections. Papers covered three general areas: (1) systems, planning, and implementation; (2) automatic and semi-automatic indexing; and (3) preservation with the bulk of the conference focusing on indexing and retrieval.published or submitted for publicatio

Exploiting object dynamics for recognition and control

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2007.Includes bibliographical references (p. 127-132).This thesis explores how state-of-the-art object recognition methods can benefit from integrating information across multiple observations of an object. Considered are active vision systems that allow to steer the camera along predetermined trajectories, resulting in sweeps of ordered views of an object. For systems of this kind, a solution is presented that exploits the order relationship between successive frames to derive a classifier based on the characteristic motion of local features across the sweep. It is shown that this motion model reveals structural information about the object that can be exploited for recognition. The main contribution of this thesis is a recognition system that extends invariant local features (shape context) into the time domain by adding the mentioned feature motion model into a joint classifier. Second, an entropy-based view selection scheme is presented that allows the vision system to skip ahead to highly discriminative viewing positions. Using two datasets, one standard (ETH-80) and one collected from our robot head, both feature motion and active view selection extensions are shown to achieve a higher-quality hypothesis about the presented object quicker than a baseline system treating object views as an unordered stream of images.by Philipp Robbel.S.M

Probabilistic geometric grammars for object recognition

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 121-123).This thesis presents a generative three-dimensional (3D) representation and recognition framework for classes of objects. The framework uses probabilistic grammars to represent object classes recursively in terms of their parts, thereby exploiting the hierarchical and substitutive structure inherent to many types of objects. The framework models the 3) geometric characteristics of object parts using multivariate conditional Gaussians over dimensions, position, and rotation. I present algorithms for learning geometric models and rule probabilities given parsed 3D examples and a fixed grammar. I also present a parsing algorithm for classifying unlabeled, unparsed 3D examples given a geometric grammar. Finally, I describe the results of a set of experiments designed to investigate the chosen model representation of the framework.by Margaret Aida Aycinena.S.M

The role of saliencey and error propagation in visual object recognition

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Includes bibliographical references (p. 162-171).by Tao Daniel Alter.Ph.D