AN INTRODUCTION TO OBJECT RECOGNITION

In this report we present a general introduction to object recognition . We begin with brief discussions of the terminology used in the objec t recognition literature and the psychophysical tasks that are used to investigate object recognition. We then discuss models of shape repre sentation. We dispense with the idea that shape representations are li ke the 3-D models used in computer aided design and explore instead mo dels of shape representation that are based on feature descriptions. A s these descriptions encode only the features that are visible from a particular viewpoint, they are generally viewpoint-specific, We discus s various means of achieving viewpoint-invariant recognition using suc h descriptions, including reliance on diagnostic features visible from a wide range of viewpoints, storage of multiple descriptions for each object, and the use of transformation mechanisms. Finally, we discuss how differences in viewpoint dependence that are often observed for w ithin-category and between-category recognition tasks could be due to differences in the types of features that are naturally available to d istinguish among different objects in these tasks.