Taking GIS to the Web
A primer for getting your bearings
on Internet-based mapping software
- By Patrick Marshall
- Apr 08, 2002
The saying about a picture being worth a thousand words may not always be true, but it certainly applies to most of the information handled by federal agencies.
Such things as trade patterns, census data and environmental hazards often can be visualized better when they are displayed on maps. If the maps are on the Internet and citizens, agency staff and contractors can find the information they need, their value is even greater.
At the Commerce Department's International Trade Association Web site (ese.export.gov), it only takes a few clicks to call up a world map showing which countries have imported the highest values of U.S. paper products. The Web site also can display which countries have experienced the greatest increases in imports of computers and electronic products from California.
Or if you're concerned about ways to fight fires in your area, take a look at GeoMAC, a collaborative effort of the Interior Department's U.S. Geological Survey, the Agriculture Department's Forest Service and other agencies. GeoMAC is an Internet mapping tool originally designed for coordinating firefighting efforts, but it's also available to the public at www.geomac.gov.
These are just two examples of the growing number of sites being offered by federal agencies and departments that employ geographical information system (GIS) programs to deliver interactive maps and data to the Web and secure intranets.
GIS programs have been growing ever more popular in government agencies, thanks to their ability to enrich traditional data by combining it with geographic data. The programs are being used for varied purposes, from analyzing crime patterns to allocating aid in urban areas to dispatching emergency-response teams to disaster sites.
The basis of a GIS program is simple. Using the program, you either create or import geometric features — points, lines and regions. The features are tied to a coordinate system, just like the latitude and longitude coordinates in an atlas. Next, you attach data to the same coordinates. It may be demographic data attached to ZIP codes or census tracts, or it may be environmental data attached to specific map coordinates. Some programs even allow you to include elevation data, making it possible to do 3-D analysis for purposes such as analyzing water runoff.
This week, we review MapInfo Corp.'s MapInfo Professional 6.5 and its Internet-serving software, MapXtreme. Next week, we will review ESRI's new ArcGIS and ArcIMS, its Internet-serving software, as well as Caliper Corp.'s Maptitude for the Web 4.5.
MapInfo: Stepping up in GIS
Originally developed as a desktop application geared toward the needs of end users — rather than the needs of cartographers or applications developers — MapInfo Professional gradually has been acquiring the development muscle and map-creation tools that were previously the exclusive domain of workstation-based heavyweights such as ESRI's ArcInfo/ArcView and Intergraph Corp.'s GeoMedia.
With Version 6.5 and the soon-to-be-released Version 7.0, MapInfo continues the march toward the upper reaches of enterprise-level professional GIS.
In addition to a solid set of basic map-creation and digitizing tools, MapInfo Professional offers extras not found in many desktop GIS programs, such as gradient shading, which allows you to effectively display such data as temperatures and elevations on a grid map, as well as contour and smoothing tools, which takes the angles out of the polylines, a series of straight lines connected by nodes. Version 6.0 of the program, which we reviewed online on Sept. 27, 2000, added the ability to display gradients in 3-D.
We were also impressed with MapInfo's ability to easily create polygons around existing map objects, a feature that greatly simplifies a number of map-creation tasks.
Version 6.5 of MapInfo adds still more advanced features. We especially enjoyed the slickness of the program's new raster translucency feature. When you place a raster image on a map layer, Version 6.5 enables you to set a measure of translucency, allowing underlying layers to show through.
Less dramatic but at least as significant, Version 6.5 has added support for additional grid file formats — digital elevation model (DEM), or digital terrain elevation data (DTED) or GTOPO30, a global DEM. Taken together, these enhancements greatly improve MapInfo Professional's ability to display terrain.
MapInfo has also improved the program's basic feature-creation tools, especially the ability to create multipoint objects, to create collections of objects of the same or different types, to control snap tolerances and to disaggregate objects.
Still, MapInfo has a way to go if it aims to eventually compare with the map-creation capabilities of the likes of ESRI's new ArcGIS suite. MapInfo has a theoretical limitation of a million nodes for a single object. In practice, however, very few maps consist of a single object and therefore have a limit of 32,000 nodes when multiple objects exist in a single file — limits that can be exceeded with large and detailed maps. What's more, MapInfo does not support remote processing to improve performance during map creation as ArcGIS does.
MapInfo also has enhanced the program's analytic and display capabilities, areas that have long been strong points for the software. In addition to the broad variety of theme maps available in earlier versions, Version 6.5 includes a new "prism" map feature that enables you to display 3-D extrusion of regions depending on a specified value.
You might, for example, show a map of the United States, with each state a different height depending upon the size of its population. At the same time, of course, you can effectively display a different variable using color ranges.
We continue to be impressed by broad support for projections and external databases — most recently, support for Oracle 8.17 — as well as by the speed with which the company provides support for new versions of major databases.
Unlike some GIS programs, including ArcGIS, MapInfo has adopted the strategy of "living inside" external databases. All data operations are performed within the external databases, so synchronization of data is not an issue. In addition, security enforced by the database does not have to be duplicated in the GIS program. The only drawback is a potential performance slowdown when large amounts of data are processing.
Serving to the Web
In MapXtreme, MapInfo also offers a surprisingly strong set of tools for serving interactive maps to the Web. We tested the Microsoft Corp. Windows version of the program, although it is available in a Java version, which, until the next version is released, offers somewhat more flexibility in application development.
MapXtreme c0mprises four primary modules. The Geoset Manager allows you to keep collections of map layers and their settings at hand so that you don't have to open them individually when employing them in Web applications.
The server administrator makes it easy to configure runtime instances of MapXtreme and to specify the geosets to be employed.
MapInfo has also included an easy-to-use application wizard that makes it simple to generate some basic Web applications. We were pleased to see that MapInfo provides a tool, MapXstress, for estimating performance based on simulated user loads and, when appropriate, to increase the number of MapXServers running.
The Bottom Line
As with previous versions, MapInfo offers users an attractive feature set — backed by extensive consulting services — in an attractively priced and scalable product line.
It's true that MapInfo doesn't offer as extensive a set of optional add-ins as ESRI does, though it does integrate such optional tools as Global Positioning System and enhanced geocoding tools. Nor does MapInfo offer map-creation tools that mimic computer-aided design, as ArcGIS does. And those wanting to perform application development should take note that MapInfo application development requires the proprietary programming languages MapBasic and MapX.
If these limitations aren't deal killers for your agency or department, you'll find MapInfo to be a very strong combination of power, ease of use and affordability.
How We Tested
A sense of direction
In this update, we looked at the three top scorers in our previous comparison in September 2000 — solutions from ESRI, Caliper Corp. and MapInfo Corp. This time, in addition to assessing the general tools provided for map creation and analysis, we gave special weight to two factors of growing importance to users in federal agencies.
First, we compared the tools provided for moving interactive maps to the Web. Second, we examined the ease with which each program integrated with external data. This includes both the program's ability to employ shape files and other geographic data in a variety of formats and the program's ability to integrate with nongeographic data in external databases.
We decided to refrain from assigning comparative scores for this review. Each program aims to fulfill different user needs, and in fact, many departments and agencies employ two or three of the solutions for different tasks.
Our goal in this comparison is to provide readers with information that will be helpful in deciding which application might best suit specific GIS needs.