Scale and Orientation-invariant Scene Similarity Metrics for Image Queries

In this paper we extend our previous work on shape-based queries to support queries on configurations of image objects. Here we consider spatial reasoning, especially directional and metric object relationships. Existing models for spatial reasoning tend to rely on pre-identified cardinal directions and minimal scale variations, assumption that cannot be considered as given in our image applications, where orientations and scale may vary substantially, and are often unknown. Accordingly, we have developed the method of varying baselines to identify similarities in direction and distance relations. Our method allows us to evaluate directional similarities without a priori knowledge of cardinal directions, and to compare distance relations even when query scene and database content differ in scale by unknown amounts. We use our method to evaluate similarity between a user-defined query scene and object configurations. Here we present this new method, and discuss its role within a broader image retrieval framework

Archaeoastronomy in the Khmer heartland

The heartland of the Khmer empire is literally crowded by magnificent monuments built in the course of many centuries. These monuments include the world-famous state-temples, such as Angkor Wat, but also many other temples and huge water reservoirs. Using Google Earth data as well as GIS data and reconstructing the ancient sky with Stellarium, we investigate here on the relationships of astronomy with orientation and topography in a systematic fashion, following the methods of modern Archaeoastronomy and strictly keeping at a bay vague or esoteric proposals put forward by many authors in the past. As a result, a very clear pattern of cardinal orientation and alignment arises, connected with the temple's symbolism and the management of power by the Khmer kings. As a bonus, the comparison with the Angkor monuments allows to put forward a explanation for the anomalous orientation of the unique two peripheral state temples of Cambodia.Comment: Archaeoastronomy/History of Astronom

A decidable weakening of Compass Logic based on cone-shaped cardinal directions

We introduce a modal logic, called Cone Logic, whose formulas describe properties of points in the plane and spatial relationships between them. Points are labelled by proposition letters and spatial relations are induced by the four cone-shaped cardinal directions. Cone Logic can be seen as a weakening of Venema's Compass Logic. We prove that, unlike Compass Logic and other projection-based spatial logics, its satisfiability problem is decidable (precisely, PSPACE-complete). We also show that it is expressive enough to capture meaningful interval temporal logics - in particular, the interval temporal logic of Allen's relations "Begins", "During", and "Later", and their transposes

Kinematics nomenclature for physiological accelerations with special reference to vestibular applications

Kinematics nomenclature for physiological accelerations and special reference to vestibular apparatu