The Robotics Institute

Carnegie Mellon Robotics Institute

Copyright notice: This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. These works may not be reposted without the explicit permission of the copyright holder.

Abstract

The structure-from-motion problem has been extensively studied in the field of computer vision. Yet, the bulk of the existing work assumes that the scene contains only a single moving object. The more realistic case where an unknown number of objects move in the scene has received little attention, especially for its theoretical treatment. In this paper we present a new method for separating and recovering the motion and shape of multiple independently moving objects in a sequence of images. The method does not require prior knowledge of the number of objects, nor is dependent on any grouping of features into an object at the image level. For this purpose, we introduce a mathematical construct of object shapes, called the shape interaction matrix, which is invariant to both the object motions and the selection of coordinate systems. This invariant structure is computable solely from the observed trajectories of image features without grouping them into individual objects. Once the matrix is computed, it allows for segmenting features into objects by the process of transforming it into a canonical form, as well as recovering the shape and motion of each object. Even though the theory works under a broad set of projection mod& (scaled orthography, paraperspective and affine), they must be linear, in other words, it, does not work with projective "cameras".

Notes

Associated Center(s) / Consortia: Vision and Autonomous Systems Center

Text Reference

Jo? Costeira and Takeo Kanade, "A Multi-body Factorization Method for Independently Moving Objects," tech. report CMU-RI-TR-97-30, Robotics Institute, Carnegie Mellon University, May, 1997

BibTeX Reference

@techreport{Kanade_1997_914,
   author = "Jo? Costeira and Takeo Kanade",
   title = "A Multi-body Factorization Method for Independently Moving Objects",
   booktitle = "",
   institution = "Robotics Institute",
   month = "May",
   year = "1997",
   number= "CMU-RI-TR-97-30",
   address= "Pittsburgh, PA",
}

The Robotics Institute

Menu