Sample / Ioup Tile-Based Geospatial Information Systems

Principles and Practices
1. Auflage 2010
ISBN: 978-1-4419-7631-4
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 237 Seiten

Tile-based mapping systems have grown to become the dominant form of mapping system with the rise of Web-based mapping tools. The origin of this book is a desire to collect all our discoveries, techniques, and best practices for creating a til- mapping system into one combined volume. The intent of this text is to provide a comprehensive guide to the theory behind creating a tiled-map system as well as a practical guide to create a concrete implementation. Stennis Space Center, MS John Sample May 2010 Elias Ioup vii Acknowledgements The authors would like to thank the Naval Research Laboratory's Base Program, program element number 0602435N, for sponsoring this research. Additionally, the following people provided technical assistance without which this book would not have been possible: Perry Beason, Frank McCreedy, Norm Schoenhardt, Brett Hode, Bruce Lin, Annie Holladay, Juliette Ioup, and Hillary Mesick. ix Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1 Background of Web-Based Mapping Applications . . . . . . . . . . . . . . . 1 1. 2 Properties of tile-based mapping systems . . . . . . . . . . . . . . . . . . . . . . . 2 1. 3 Book Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Logical Tile Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. 2 Global Logical Tile Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. 3 Blue Marble Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2. 4 Mercator-Based Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. 5 Variable Start Tile Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2. 6 Standardized Schema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 Tiled Mapping Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3. 1 Tile Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3. 1. 1 Discrete Map Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3. 1. 2 Continuous Map Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3. 2 Tile Retrieval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3. 2. 1 Local Tile Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dr. John T. Sample has worked for 12 years as a scientist in the Naval Research Laboratory's Geospatial Sciences and Technology branch. He has authored and edited articles, books, and book chapters on the topic of web based GIS. He currently has two patents granted related to web based GIS. He has developed a number of tile-based mapping systems in use by the Department of Defense and Department of Homeland Security. Dr. Sample received a Ph.D. in computer science from Louisiana State University in 2003 and a B.S. in mathematics from the University of Southern Mississippi in 1999.Elias Z. K. Ioup is a Computer Scientist with the Naval Research Laboratory working on several geospatial research programs. He is the principal investigator for the GHUB Distributed Geospatial Repository program and a lead developer on the Geospatial Information Database (GIDB). These programs represent leading DoD efforts to leverage geospatial capabilities using Service Oriented Architectures and Web services. Elias Ioup received a Master's degree in Computer Science from the University of New Orleans in 2006 and Bachelor's degrees in Mathematics and Computer Science from the University of Chicago in 2003. He is currently a Ph.D. candidate in Engineering and Applied Science at the University of New Orleans.

Autoren/Hrsg.

Sample, John T.

Ioup, Elias

Inhaltsverzeichnis

1;Preface;8
2;Acknowledgements;10
3;Contents;12
4;1 Introduction;16
4.1;1.1 Background of Web-Based Mapping Applications;16
4.2;1.2 Properties of tile-based mapping systems;17
4.3;1.3 Book Organization;17
5;2 Logical Tile Schemes;19
5.1;2.1 Introduction;19
5.2;2.2 Global Logical Tile Scheme;21
5.3;2.3 Blue Marble Example;24
5.4;2.4 Mercator-Based Schema;25
5.5;2.5 Variable Start Tile Schemes;26
5.6;2.6 Standardized Schema;29
5.7;References;29
6;3 Tiled Mapping Clients;30
6.1;3.1 Tile Calculation;30
6.1.1;3.1.1 Discrete Map Scales;31
6.1.2;3.1.2 Continuous Map Scales;33
6.2;3.2 Tile Retrieval;35
6.2.1;3.2.1 Local Tile Storage;36
6.2.2;3.2.2 Network Tile Retrieval;36
6.3;3.3 Generating the Map View;38
6.3.1;3.3.1 Discrete Scales Map View;38
6.3.2;3.3.2 Continuous Scales Map View;39
6.4;3.4 Example Client;41
6.5;3.5 Survey of Tile Map Clients;41
7;4 Image Processing and Manipulation;47
7.1;4.1 Basic Image Concepts;47
7.2;4.2 Geospatial Images;49
7.2.1;4.2.1 Specialized File Formats;49
7.3;4.3 Image Manipulation;51
7.3.1;4.3.1 Interpolation 1: Nearest Neighbor;56
7.3.2;4.3.2 Interpolation 2: Bilinear;57
7.3.3;4.3.3 Interpolation 3: Bicubic;58
7.4;4.4 Choosing Image Formats for Tiles;63
7.5;4.5 Choosing Tile Sizes;69
7.6;4.6 Tuning Image Compression;77
7.7;References;91
8;5 Image Tile Creation;92
8.1;5.1 Tile Creation from Random Images;93
8.2;5.2 Tile Creation Preliminaries;94
8.2.1;5.2.1 Bottom-Up Tile Creation;94
8.2.2;5.2.2 Choosing the Base Level for a Set of Source Images;94
8.2.3;5.2.3 Pull-Based Versus Push-Based Tile Creation;98
8.3;5.3 Tile Creation Algorithms;99
8.3.1;5.3.1 Scaling Process for Lower Resolution Levels;100
9;6 Optimization of Tile Creation;107
9.1;6.1 Caching Tile Sets in Memory to Improve Performance;107
9.2;6.2 Partial Reading of Source Images;109
9.2.1;6.2.1 Reading Random Areas from Source Images;110
9.2.2;6.2.2 Tile Creation with Partial Source Image Reading;113
9.3;6.3 Tile Creation with Parallel Computing;113
9.3.1;6.3.1 Multi-Threading of Tile Creation Algorithms;114
9.3.2;6.3.2 Tile Creation for Distributed Computing;115
9.3.2.1;6.3.2.1 MPI;116
9.3.2.2;6.3.2.2 MapReduce;117
9.3.2.3;6.3.2.3 Ad Hoc Clustering;118
9.4;6.4 Partial Updating of Existing Tiled Image Sets;118
9.5;References;126
10;7 Tile Storage;127
10.1;7.1 Introduction to Tile Storage;127
10.2;7.2 Storing Image Tiles as Separate Files;128
10.3;7.3 Database-Based Tile Storage;131
10.4;7.4 Custom File Formats;131
10.5;7.5 Comparative Performance;132
10.5.1;7.5.1 Writing Tests;133
10.5.2;7.5.2 Reading Tests;134
10.5.2.1;7.5.2.1 Random Tile Access Tests;134
10.5.2.2;7.5.2.2 Effect of Cached Tile Data;135
10.6;7.6 Storage of Tile Metadata;136
10.7;7.7 Storage of Tiles in Multi-Resolution Image Formats;136
10.8;7.8 Memory-Cached Tile Storage;137
10.9;7.9 Online Tile Storage;137
11;8 Practical Tile Storage;142
11.1;8.1 Introduction to Tile Indexes;142
11.2;8.2 Storage by Zoom Level;145
11.3;8.3 Introduction to Tile Clusters;147
11.4;8.4 Tile Cluster Files;148
11.5;8.5 Multiple Levels of Clusters;149
11.6;8.6 Practical Implementation of Tile Clusters;150
11.7;8.7 Application to Memory Cached Tiles;151
11.8;8.8 Application to Distributed Computing;151
11.9;8.9 Performance Optimizations of Tile Cluster Method;151
12;9 Tile Serving;159
12.1;9.1 Basics of HTTP;159
12.2;9.2 Basic Tile Serving;160
12.3;9.3 Tile Serving Scheme with Encoded Parameters;161
12.4;9.4 Tile Serving Scheme with Encoded Paths;163
12.5;9.5 Service Metadata Alternatives;164
12.6;9.6 Conclusions;165
12.7;References;172
13;10 Map Projections;173
13.1;10.1 Introduction to Datums, Coordinate Systems, and Projections;173
13.1.1;10.1.1 The Shape of the Earth;173
13.1.2;10.1.2 Datums;174
13.1.3;10.1.3 Coordinate Systems;177
13.2;10.2 Map Projections;177
13.2.1;10.2.1 Different Map Projections;178
13.2.2;10.2.2 Cylindrical Equidistant Projection;179
13.2.3;10.2.3 Cylindrical Equal-Area Projection;180
13.2.4;10.2.4 Mercator;180
13.2.5;10.2.5 Universal Transverse Mercator;180
13.3;10.3 Point Reprojection;183
13.4;10.4 Map Reprojection;185
13.4.1;10.4.1 Affine Transforms;185
13.4.2;10.4.2 Interpolation;187
13.4.3;10.4.3 Point-wise Reprojection;188
13.4.4;10.4.4 Tablular Point-Wise Reprojection;190
13.5;10.5 Map Projections for Tiled Imagery;192
13.5.1;10.5.1 Storing Tiles in the Geodetic Projection;192
13.5.2;10.5.2 Storing Tiles in the Mercator Projection;193
13.5.3;10.5.3 Other Projections;194
13.5.4;10.5.4 Which Projection for a Tiled-Mapping System?;195
13.6;10.6 Conclusion;196
13.7;References;199
14;11 Tile Creation using Vector Data;200
14.1;11.1 Vector Data;200
14.2;11.2 Tile Creation;201
14.3;11.3 Queries;203
14.4;11.4 Storage;203
14.4.1;11.4.1 Database Storage;204
14.4.2;11.4.2 File System Storage;207
15;12 Case Study: Tiles from Blue Marble Imagery;211
15.1;12.1 Pull-Based Tiling;211
15.2;12.2 Push-Based Tiling;213
15.3;12.3 Results;213
16;13 Case Study: Supporting Multiple Tile Clients;227
16.1;13.1 KML Server;227
16.1.1;13.1.1 Static KML Example;227
16.1.2;13.1.2 Dynamic KML Example;229
16.2;13.2 WMS Server;229
16.2.1;13.2.1 WMS Servlet Implementation;230
16.3;References;239
17;Index;240