Tile-Based Geospatial Information Systems

by Sample, John T.; Ioup, Elias

• ISBN13: 9781441976307
• ISBN10: 1441976302
• Format: Hardcover
• Copyright: 2010-11-15
• Publisher: Springer-Verlag New York Inc

Summary

Tile-based online mapping systems have replaced traditional Web GIS systems, because of their improved speed and usability. The trend towards tile-base systems was started by Internet services companies, such as Google, Yahoo, and Microsoft. They have been followed by the traditional GIS community, government organizations and open sourcedevelopment communities, because tile based systems yield faster and work stronger with 3-D mapping tools. Tile-Based Geospatial Information Systems: Principles and Practice presents a detailed examination of the principles of tile-based systems. Topics include discussions of projections, coordinate systems, image processing, data basing and indexing requirements and web access. Attention is devoted to understanding and development of algorithms needed to make tile-based systems functional and efficient. In addition to the theoretical examination of the topic, this book includes detailed practical content helpful to those charged with implementation of tile-based systems. Case studies are provided in the last 2 chapters of this book. Tile-Based Geospatial Information Systems: Principles and Practice is designed for a professional audience composed of researchers, practitioners and government workers, focusing on geographic information systems and internet technologies and image processing techniques related to GIS. This book is also suitable for advanced-level students in computer science and geography as a secondary text or reference book.

Table of Contents

Introduction	p. 1
Background of Web-Based Mapping Applications	p. 1
Properties of tile-based mapping systems	p. 2
Book Organization	p. 2
Logical Tile Schemes	p. 5
Introduction	p. 5
Global Logical Tile Scheme	p. 7
Blue Marble Example	p. 10
Mercator-Based Schema	p. 11
Variable Start Tile Schemes	p. 12
Standardized Schema	p. 15
References	p. 15
Tiled Mapping Clients	p. 17
Tile Calculation	p. 17
Discrete Map Scales	p. 18
Continuous Map Scales	p. 20
Tile Retrieval	p. 22
Local Tile Storage	p. 23
Network Tile Retrieval	p. 23
Generating the Map View	p. 25
Discrete Scales Map View	p. 25
Continuous Scales Map View	p. 26
Example Client	p. 28
Survey of Tile Map Clients	p. 28
Image Processing and Manipulation	p. 35
Basic Image Concepts	p. 35
Geospatial Images	p. 37
Specialized File Formats	p. 37
Image Manipulation	p. 39
Interpolation 1: Nearest Neighbor	p. 44
Interpolation 2: Bilinear	p. 45
Interpolation 3: Bicubic	p. 46
Choosing Image Formats for Tiles	p. 51
Choosing Tile Sizes	p. 57
Tuning Image Compression	p. 65
References	p. 79
Image Tile Creation	p. 81
Tile Creation from Random Images	p. 82
Tile Creation Preliminaries	p. 83
Bottom-Up Tile Creation	p. 83
Choosing the Base Level for a Set of Source Images	p. 83
Pull-Based Versus Push-Based Tile Creation	p. 87
Tile Creation Algorithms	p. 88
Scaling Process for Lower Resolution Levels	p. 89
Optimization of Tile Creation	p. 97
Caching Tile Sets in Memory to Improve Performance	p. 97
Partial Reading of Source Images	p. 99
Reading Random Areas from Source Images	p. 100
Tile Creation with Partial Source Image Reading	p. 103
Tile Creation with Parallel Computing	p. 103
Multi-Threading of Tile Creation Algorithms	p. 104
Tile Creation for Distributed Computing	p. 105
Partial Updating of Existing Tiled Image Sets	p. 108
References	p. 116
Tile Storage	p. 117
Introduction to Tile Storage	p. 117
Storing Image Tiles as Separate Files	p. 118
Database-Based Tile Storage	p. 121
Custom File Formats	p. 121
Comparative Performance	p. 122
Writing Tests	p. 123
Reading Tests	p. 124
Storage of Tile Metadata	p. 126
Storage of Tiles in Multi-Resolution Image Formats	p. 126
Memory-Cached Tile Storage	p. 127
Online Tile Storage	p. 127
Practical Tile Storage	p. 133
Introduction to Tile Indexes	p. 133
Storage by Zoom Level	p. 136
Introduction to Tile Clusters	p. 138
Tile Cluster Files	p. 139
Multiple Levels of Clusters	p. 140
Practical Implementation of Tile Clusters	p. 141
Application to Memory Cached Tiles	p. 142
Application to Distributed Computing	p. 142
Performance Optimizations of Tile Cluster Method	p. 142
Tile Serving	p. 151
Basics of HTTP	p. 151
Basic Tile Serving	p. 152
Tile Serving Scheme with Encoded Parameters	p. 153
Tile Serving Scheme with Encoded Paths	p. 155
Service Metadata Alternatives	p. 156
Conclusions	p. 157
References	p. 164
Map Projections	p. 165
Introduction to Datums, Coordinate Systems, and Projections	p. 165
The Shape of the Earth	p. 165
Datums	p. 166
Coordinate Systems	p. 169
Map Projections	p. 169
Different Map Projections	p. 170
Cylindrical Equidistant Projection	p. 171
Cylindrical Equal-Area Projection	p. 172
Mercator	p. 172
Universal Transverse Mercator	p. 172
Point Reprojection	p. 175
Map Reprojection	p. 177
Affine Transforms	p. 177
Interpolation	p. 179
Point-wise Reprojection	p. 180
Tablular Point-Wise Reprojection	p. 182
Map Projections for Tiled Imagery	p. 184
Storing Tiles in the Geodetic Projection	p. 184
Storing Tiles in the Mercator Projection	p. 185
Other Projections	p. 186
Which Projection for a Tiled-Mapping System?	p. 187
Conclusion	p. 188
References	p. 191
Tile Creation using Vector Data	p. 193
Vector Data	p. 193
Tile Creation	p. 194
Queries	p. 196
Storage	p. 196
Database Storage	p. 197
File System Storage	p. 200
Case Study: Tiles from Blue Marble Imagery	p. 205
Pull-Based Tiling	p. 205
Push-Based Tiling	p. 207
Results	p. 207
Case Study: Supporting Multiple Tile Clients	p. 221
KML Server	p. 221
Static KML Example	p. 221
Dynamic KML Example	p. 223
WMS Server	p. 223
WMS Servlet Implementation	p. 224
References	p. 233
Index	p. 235
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