Qualitative Spatial and Temporal Reasoning (QSTR) is concerned with symbolic knowledge representation, typically over infinite domains. The motivations for employing QSTR techniques range from exploiting computational properties that allow efficient reasoning to capture human cognitive concepts in a computational framework. The notion of a qualitative calculus is one of the most prominent QSTR formalisms. This article presents the first overview of all qualitative calculi developed to date and their computational properties, together with generalized definitions of the fundamental concepts and methods, which now encompass all existing calculi. Moreover, we provide a classification of calculi according to their algebraic properties.
Humans are able to recognize objects in the presence of significant amounts of occlusion and changes in the view angle. In human and robot vision, these conditions are normal situations and not exceptions. In digital images one more problem occurs due to unstable outcomes of the segmentation algorithms. Thus, a normal case is that a given shape is only partially visible, and the visible part is distorted. To our knowledge there does not exist a shape representation and similarity approach that could work under these conditions. However, such an approach is necessary to solve the object recognition problem. The main contribution of this paper is the definition of an optimal partial shape similarity measure that works under these conditions. In particular, the presented novel approach to shape-based object recognition works even if only a small part of a given object is visible and the visible part is significantly distorted, assuming the visible part is distinctive. q
Qualitative spatial and temporal reasoning is based on socalled qualitative calculi. Algebraic properties of these calculi have several implications on reasoning algorithms. But what exactly is a qualitative calculus? And to which extent do the qualitative calculi proposed meet these demands? The literature provides various answers to the first question but only few facts about the second. In this paper we identify the minimal requirements to binary spatio-temporal calculi and we discuss the relevance of the according axioms for representation and reasoning. We also analyze existing qualitative calculi and provide a classification involving different notions of relation algebra.
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