Recognition by prototypes

A scheme for recognizing 3D objects from single 2D images is introduced. The scheme proceeds in two stages. In the categorization stage, the image is matched against prototype objects, and in the identification stage, the observed object is matched against the individual models of its class, where classes are expected to contain objects with relatively similar shapes. The advantage of categorizing the object before it is identified is twofold. First, the image is compared to a smaller number of models, since only models that belong to the object´s class need to be considered. Second, the cost of comparing the image to each model in a class is very low, because correspondence is computed once for the whole class. The correspondence and object pose computed in the categorization stage to align the prototype with the image are reused in the identification stage to align the individual models with the image. As a result, identification is reduced to a series of simple template comparisons