book

Web Mapping Illustrated

by Tyler Mitchell

June 2005

Beginner to intermediate

372 pages

10h 1m

English

O'Reilly Media, Inc.

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Youthful Exploration

1.1. The Power of Digital Maps
1.2.1. Personal Maps1.2.2. Technology Barriers
1.3.1. Web Map Users1.3.2. Web Sites with a Web Mapping Component1.3.2.1. Behind the web page1.3.2.2. Making your own web mapping site
2.1. Common Mapping Tasks
2.2.1. Finding Good Source Data2.2.2. Dependency on Digital Tools2.2.3. Understanding Data Formats2.2.4. Using the Right Tools
2.3.1. Viewing and Mapping2.3.2. Analysis2.3.3. Creating and Manipulating2.3.4. Conversion2.3.5. Sharing
3.1. Raster and Vector
3.3.1. Data Access and Performance3.3.2. Portability
3.4.1. Raster Formats Supported by GDAL3.4.2. Programming Libraries3.4.3. GDAL Utilities
3.5.1. Vector Formats Supported by OGR3.5.2. OGR Utilities and Examples
3.6.1. GIS Analysis with SQL
4.1. How MapServer Applications Operate
4.2.1. MapServer Executable4.2.2. MapServer's Map File4.2.3. Data Sources4.2.4. Output Map Image
4.3.1. Platforms4.3.2. Acquiring MapServer Binaries4.3.2.1. Windows versions4.3.2.2. Linux binaries4.3.2.3. Linux GIS distributions4.3.2.4. Linux RPM versions4.3.2.5. Debian Linux versions4.3.2.6. Mac OS X4.3.3. Compiling MapServer Source Code4.3.3.1. Downloading sources4.3.3.2. Configuring sources4.3.3.3. configure options4.3.3.4. Dependencies4.3.3.5. Making a compile4.3.3.6. Installation4.3.3.7. A quick test of the install
5.1. Appraising Your Data Needs5.1.1. Vector Maps or Raster Maps?5.1.2. What Kind of Vector Data Do You Require?5.1.3. What Kind of Raster Data Do You Require?5.1.4. What Scale of Map Do You Require?5.1.5. Do You Need Three Dimensions?
5.2.1. Finding Premade Maps5.2.2. Finding Satellite Images or Shaded Surface Maps5.2.3. Finding Map Data
6.1. Downloading the Demonstration Data
6.3.1. Viewing Summary Information About Airports6.3.2. Viewing Detailed Airport Location Information6.3.3. Viewing Statistics About a Satellite Image
6.4.1. Setting Up Processing Tools for Non-GNU Platforms6.4.2. Using ogrinfo to List Data in a Shapefile6.4.3. Using grep to Show Only the Names of the Airports6.4.4. Using wc to Count the Number of Airport Names6.4.5. Using sed to Find Specific Patterns in Airport Names6.4.6. Use sed to Reformat Print Results6.4.7. Using sed to Remove Lines and Trim the Front End of Lines6.4.8. Using sort to Create a List of Ordered Elevations6.4.9. Using uniq to Summarize Results of Duplicate Lines6.4.10. Other Powerful Text-Processing Tools
7.1. Converting Map Data
7.2.1. Geography Markup Language (GML)7.2.2. Converting a Shapefile to GML7.2.3. Creating a New File with Only a Subset of Point Features7.2.4. Putting One Airport to a New Shapefile7.2.5. Converting Shapefiles to Other File Formats7.2.6. Converting to a PostgreSQL Database
7.3.1. Translating an Image to Another Format7.3.2. Using gdal_translate to Create a JPEG Preview of a Satellite Image7.3.3. Clipping an Area of Interest and Creating a Small JPEG of a Satellite Image
8.1. Visualization and Mapping Programs8.1.1. Other Open Source Mapping Programs8.1.2. Other Free-to-Use Programs8.1.3. Other Commercial Programs
8.2.1. Installing OpenEV8.2.2. Loading Sample Map Data into OpenEV8.2.3. Open the Airports Shapefile8.2.4. Using the Layers Window8.2.5. Changing General Layer Settings8.2.6. Changing Draw Styles for Layers8.2.7. Adding More Data to the View
8.3.1. Zooming8.3.2. Panning8.3.3. Color Theming8.3.4. Loading a Raster8.3.5. Reprojecting Data to Match Another Layer8.3.6. Creating a 3D View8.3.6.1. Preparing the Digital Elevation Model8.3.6.2. Preparing the drape image8.3.6.3. Initiating the 3D view8.3.6.4. Navigating the 3D view
9.1. Planning Your Map9.1.1. Choosing a General Scale and Extent9.1.2. Identifying Data Requirements for Your Base Map9.1.3. What Are Your Sources?9.1.3.1. GPS9.1.3.2. Air photo interpretation9.1.3.3. Derived products9.1.3.4. Local knowledge
9.2.1. Clipping Out an Area of Interest9.2.2. Starting to Draw Your Map Features9.2.2.1. Mapping locations of interest (point data)9.2.2.2. Creating and saving tabular attributes9.2.2.3. Mapping roads and transportation paths (linear datalinear data9.2.2.4. Mapping regions of interest (area/polygons data)
10.1. MapServer Utilities
10.2.1. Acquire Some Mapping Data10.2.2. Creating a Simple MapServer Map File10.2.3. Map File Rules and Recommendations10.2.4. Creating Your First Map Image10.2.5. Adding Labels to the Map10.2.6. Determining the Extent of a Country10.2.7. Color Theming the Map10.2.8. Understanding Operators10.2.9. Creating a Map Legend10.2.10. Adding a Scale Bar Using the scalebar Command10.2.11. The Final Map File
11.1. Preparing and Testing MapServer11.1.1. MapServer for Windows (MS4W)11.1.2. MapServer on Linux with Apache11.1.3. Configuring Apache11.1.3.1. Windows temporary image folder location11.1.3.2. Linux temporary image folder location11.1.4. Testing and Troubleshooting11.1.4.1. Testing mapserv.exe on Windows11.1.4.2. Testing mapserv with Apache on Linux11.1.5. Testing the MapServer Setup Using a Demo Application
11.2.1. Changing the Initial Extent of the Map11.2.2. Changing the Map Projection11.2.2.1. Setting the map and layer projections11.2.2.2. Choosing an output map projection11.2.2.3. EPSG projection codes versus project details11.2.2.4. Modifying the map extent11.2.3. Modifying Image Size to Better Fit the Extent of the Map11.2.4. Adding Zoom and Recenter Tools to the Web Page11.2.5. Adding a List of Layers to Choose From11.2.6. Adding a Legend to the Application11.2.6.1. Removing the embedded legend from the map file11.2.6.2. Adding the legend graphic to the web page11.2.6.3. Adding a link to the legend image11.2.7. Adding a Scale Bar to the Application11.2.8. Adding an Overview/Reference Map to the Application
12.1. Web Services for Mapping
12.2.1. Why Use These Services?12.2.2. Internal Versus External Needs
12.3.1. Web Map Service (WMS)12.3.1.1. Checking the capabilities of a WMS provider12.3.1.2. Manually requesting a map from a WMS source12.3.1.3. Adding a WMS layer to a MapServer map file12.3.1.4. Using MapServer as a WMS server12.3.1.5. Checking your own WMS capabilities document12.3.2. Web Feature Service (WFS)12.3.2.1. Checking the capabilities of a WFS provider12.3.2.2. Manually requesting data from a WFS source12.3.2.3. Adding a WFS layer to a MapServer map file12.3.2.4. Using MapServer as a WFS server12.3.2.5. Checking your own WFS capabilities document
13.1. Introducing PostGIS
13.2.1. Server-Based GIS
13.3.1. PostGIS for Windows13.3.2. PostGIS for Linux13.3.2.1. RPM packages13.3.2.2. Debian packages13.3.3. PostGIS for Mac OS X
13.5.1. Getting PostgreSQL Up and Running13.5.2. Enabling pl/pgsql Language Support13.5.3. Loading the postgis.sql Script13.5.4. Loading the spatial_ref_sys.sql Script13.5.5. Testing PostGIS Functionality
13.7.1. Using shp2pgsql13.7.2. Using ogr2ogr
13.8.1. Building Spatial Indexes13.8.2. Critical Tabular Indexes13.8.3. Querying for Spatial Proximity13.8.3.1. Find the county for a given point13.8.3.2. Querying for nearby county polygons13.8.3.3. Planning to visualize query results
13.9.1. Exporting PostGIS Data into a Shapefile or GML13.9.2. Viewing PostGIS Data in OpenEV13.9.3. Viewing PostGIS Data in MapServer13.9.3.1. Highlighting a subset of shapes13.9.3.2. Using subqueries for more complex SQL13.9.3.3. Using PostGIS attributes to draw labels13.9.4. Using PostGIS in Other Applications13.9.4.1. ArcMap and PostGIS
14.1. Introducing MapScript
14.2.1. Building MapScript from Source Code14.2.2. Obtaining Binary Versions of MapScript14.2.3. Getting Help
14.4.1. Opening the Map File and Drawing the Map14.4.2. Manipulating Map Settings14.4.3. Creating a Map File from Scratch
A.1. The Third Spheroid from the SunA.1.1. Geographic Coordinate SystemA.1.1.1. Decimal degrees versus degrees minutes secondsA.1.2. Map Projections: Flattening the SpheroidA.1.3. Planar/Projected Coordinate System
A.2.1. EPSG CodesA.2.1.1. EPSG versus epsg
A.3.1. Simple Cylindrical ProjectionA.3.1.1. MapServer syntaxA.3.2. Orthographic ProjectionA.3.2.1. MapServer syntaxA.3.3. Mercator ProjectionA.3.3.1. MapServer syntaxA.3.4. Transverse Mercator ProjectionA.3.4.1. MapServer syntaxA.3.5. Albers Equal Area ProjectionA.3.5.1. MapServer syntaxA.3.6. Stereographic ProjectionA.3.6.1. MapServer syntaxA.3.7. Universal Transverse Mercator ProjectionA.3.7.1. MapServer syntax
B.1. Vector DataB.1.1. MapServer and Vector Data AccessB.1.1.1. Using OGRB.1.2. Data Format TypesB.1.2.1. File-based dataB.1.2.2. Directory-based dataB.1.2.3. Database connections

Content preview from Web Mapping Illustrated

Converting Vector Data

Quite often data isn't in a format that makes it readily available for both mapping software and people to read. Many data formats store the geographic data in a binary format. This format is normally readable only by computers and is designed for software to use. Some spatial data formats are in a simple text format, which is easier to explore.

Geography Markup Language (GML)

One example of a text-based format is Geography Markup Language (GML). It uses a text syntax to encode coordinates into a text file. GML can then be read or manually edited without needing a special piece of software or at least nothing more than a common text editor. Creating GML from scratch isn't very pleasant. Fortunately, another OGR utility exists that can convert OGR-supported data formats into and out of other formats, including GML.

GML has three different versions: GML1, GML2, and GML3. There are many sub-versions as well. The differences between versions can be a problem because certain features may not be directly transferable to another. The tools introduced in this chapter use ogr2ogr, which outputs to GML2 format.

GML was designed to be suitable for data interoperability, allowing the exchange of spatial data using a common format. This has opened up the possibilities for various web services that operate using different software yet can communicate using this standard format. See Chapter 12 to learn more about this example.

GML's downside is its size. Text files can't hold ...