No description available.

The representation of terrain by a regular grid Digital Elevation Model (DEM) requires a large amount of data which increases with the resolution. The nature of the typical applications of terrain data, for example, aeronautical navigation, dictates that the reliability of the data is of prime importance. Thus any compression scheme used for compressing OEMs, in the presence of errors, must be able to achieve competitive compression while retaining a level of accuracy in the decompressed data. The requirements for effective data compression and error control tend to conflict. In some situations, for example, mobile storage devices used in hostile environments, the use of both techniques is essential. In this research the use of data compression for a storage channel subject to error is considered. The suitability of some standard data compression techniques (statistical and dictionary based methods) for robust terrain compression, is examined. The results indicate, as expected, that these methods, as they stand, are unable to tolerate any error in the compressed data. Five possible methods for the robust progressive compression of terrain data, based on common image and other compression methods, are developed and implemented. The five methods are a bit splitting method, a grid interpolation method, a discrete cosine transform based method, a vector quantization based method and a linear quadtree method. All methods are used in conjunction with a statistical encoder. Each method identifies the information critical for obtaining a good approximation to the original terrain, and thus the information which requires strong error control. It is shown that grid interpolation is the natural choice for lossless robust DEM compression. A progressive strategy which incorporates various levels of data is employed. The levels are formed by down-sampling the data to form a coarse and fine grid of elevations. Grid interpolation techniques are then employed to obtain an approximation of the fine grid from the coarse grid. The corrections to this approximation are then compressed using an arithmetic encoder. This process is done repeatedly to produce the required number of levels. Protection is achieved primarily through the use of BCH codes. The protection is incorporated in such a way that the coarsest levels of data receive stronger error control. Secondary error detection mechanisms exist through the use of the arithmetic encoder and also some prior knowledge of the compressed data. The software developed here proves to be successful with regard to progressively reconstructing terrain in the presence of errors, while also producing compression results which compare favourably with theoretical results based on a known DEM compression method. Consideration is also given to the task of validating the decompressed data, and determining if terrain data may be distinguished from other digital data. A series of tests which use the grid interpolation and DCT methods discussed previously are used, along with Moran's Index, to measure spatial auto correlation. Local tests based on image processing techniques (edge and point detection masks) are also employed to detect any anomalies in data which may otherwise be classified as terrain. The results indicate that while the differentiation of terrain and uncorrelated data is a relatively straightforward task, the task of distinguishing between terrain data and other correlated data provides great scope for further research.

Thesis (M.S.)--University of Arkansas, Fayetteville, 2000. / "August 2000." Includes bibliographical references (leaves 74-76).

Thesis (Master)--İzmir Institute Of Technology, İzmir, 2005. / Keywords: image segmentation, remote sensing, dynamic programming, aerial images, Coastline matching, coastline extraction. Includes bibliographical references (leaves. 61-63).

Thesis (Ph. D.)--University of Idaho, 2005. / Abstract. "December, 2005." Includes bibliographical references. Also available online in PDF format.

Maps are among the oldest and the most popular forms of graphical communication, which have always been highly regarded for high efficiency of information transfer. Regardless of how efficient two-dimensional maps are, three-dimensional interactive maps offer significant improvements and benefits over their traditional counterparts. While the enabling technologies for three-dimensional (3D) mapping have been ready for some time, and the benefits are significant, one might expect that a wide adoption of threedimensional maps should already be happening. However, for some reason, the transition to 3D cartography is not happening as quickly and effectively, as would be allowed by the technological and social conditioning. In this work we discuss three-dimensional interactive maps in depth from both the theoretical and practical perspective, as well as show the benefits for a number of applications, and identify some of the factors that inhibit their popularization. We define 3D maps and threedimensional cartography, and discuss its relations with the broader discipline of geovisualization. We demonstrate that more 3D cartographic research would benefit users of maps, as well as those of GIS and geovisualization products. Three-dimensional maps are such a broad subject, and they encompass so many different things, that hard definitions are difficult. That is why we use a technical description and propose a set of functional factors that differentiate, describe and define threedimensional maps, instead of trying to provide a single narrow definition. We also discuss and validate various cartographic, functional, practical and technical aspects of three-dimensional maps, by a practical exercise of implementation of a 3D mapping platform. The platform developed, called the 3D Map Viewer, is used to demonstrate the usefulness of 3D maps, and discuss a number of applications where they offer benefits over the existing approaches. By applying our platform to different tasks we also prove that efficient 3D mapping products may be built today, without a need for further technological progress. We believe that the adoption of 3D cartography would benefit a widerange of users, and that it has a potential to stimulate progress in numerous disciplines of business, life and science. It is our objective to contribute to widespread recognition of three-dimensional maps’ usefulness, and to adhere to their continued development and popularization.

This thesis describes automated cartographic name placement using rule-based systems. In particular it describes the problem involved with designing a system which is flexible enough to place names on a variety of maps. This is demonstrated using logic programming techniques written in PROLOG. Most previous name placement systems are either map specific or have demonstrated only a few aspects of name placement. However two of these systems, which use the rule-based approach for solving the name placement problem, do show greater flexibility. Nevertheless all known results from these seem unsophisticated when compared to many manually produced maps. This thesis describes further research into the use of rule-based systems. The systems described have the capability to handle a wider range of maps of greater complexity. Also described is a procedural program which implements an iterative strategy for name placement on the Ordnance Survey Route Planner map. The research attempts to classify label positions and configurations used on a wide range of maps and discusses ways of implementing these in an automated name placement system. A range of name placement rules are also studied in order to decide what type of data a flexible automated name placement system must be able to access. A combined vector and raster data structure approach is adopted. This supplies the necessary "visual" information needed to apply most of the name placement rules. Name placement and database primitives are used to construct the high level rules which make up the rule-based systems. This work has been undertaken in collaboration with the Ordnance Survey. The procedural name placement program, capable of placing names on the 1:625000 Route Planner map, has been implemented at their headquarters.

No description available.

No description available.

Thesis (M.S. in computer science)--Washington State University, December 2007. / Includes bibliographical references (p. 62-66).