Web-Mapping Hacks

September 1, 2005 By: Jonathan W. Lowe

In your life as a geospatial practitioner, how many curious colleagues brand new to all things geospatial have asked, "Can you recommend one or two good books introducing GIS?" What these colleagues want is a book that not only explains geospatial concepts, but also teaches the hands-on use of GIS tools. There are plenty of textbooks providing the concepts of geospatial computing — explaining map projections, differentiating vector from raster, cautioning against cartographic deception, and so on — but they don't include tutorials with real software. You'll often find excellent geospatial tutorials in the manuals accompanying proprietary GIS vendor software, but, understandably, your typical colleague isn't prepared to invest $1,500 in commercial GIS products just to satisfy his curiosity. So, for years, I've had no appropriate answer to requests for introductory GIS books.

Jonathan W. Lowe

Next time I'm asked, though, I'll point out two new O'Reilly titles: Web Mapping Illustrated by Tyler Mitchell and Mapping Hacks by Schuyler Erle, Rich Gibson, and Jo Walsh. Both illustrate general concepts with step-by-step tutorials that revolve entirely around free, open-source geospatial tools. Based on these books, our curious colleagues can take GIS for an immediate test drive by downloading the freely available software. While appropriate as introductory texts, these new books are also useful to experienced practitioners, particularly those comparing open-source software with proprietary competitors. And O'Reilly's usual clean formatting, attention to technical detail, and solid editing make for a smooth read. This column reviews both books.

Exploiting Open-Source Toolkits

Mitchell's Web Mapping Illustrated: Using Open Source GIS Toolkits introduces his readers to geospatial applications with the ultimate goal of serving interactive maps on the Internet. Within this context, Mitchell covers the concepts and tools of general digital mapping, Web mapping, data management, and spatial database management. The tutorials use OpenEV, UMN (University of Minnesota) MapServer, PostGIS, and the Geospatial Data Abstraction Library (GDAL) with OGR. All are freely available online for Linux, UNIX, Mac, and Windows platforms.

After a conceptual tour of digital mapping and tools, Mitchell launches into the book's main purpose: a tutorial that leaves the reader with an interactive mapping Web site fed by a spatial database and capable of delivering Open Geospatial Consortium (OGC)-compliant Web mapping or Web feature services. The tutorial begins with installation instructions for UMN's MapServer, software that accepts map requests from a HyperText Transfer Protocol server such as Apache and returns map images or feature coordinates. Because MapServer provides such core functionality, people from a wide range of backgrounds want it to run on their favorite system. Known supported systems are Windows 2000, XP, and 95; Linux (RedHat/SuSE/Debian/Mandrake, versions 6 – 9); Solaris; Mac OS X Panther; VMware running Windows and Linux; FreeBSD; SCO Open-Server; and SGI IRIX. (If MapServer doesn't yet work on your favorite platform, you may be able to modify the source code to make it work.) MapServer is a small package but capable of extension to a variety of other open-source tools, spatial databases, and data input and output formats — serving maps as PDF documents, for instance. To use the extra options, they must be enabled when installing MapServer. Mitchell devotes a whole chapter to explaining that process. And for the faint of heart (or just busy), the chapter closes with contact information for 20 organizations that provide commercial services for MapServer.