In September of 1997, Environmental Systems Research Institute (ESRI) released version 1 of ArcExplorer. Since that time, over 500,000 copies of the product have been distributed. If it's not there already, ArcExplorer is on its way toward being the most widely used GIS product in the world, all within a span of 18 months.

ArcExplorer is a GIS data viewer with surprisingly strong and deep features. In addition to the expected zoom, pan, and identify tools, these features include:

• robust layer handling, including zoom layering
• thematic mapping - single symbol, unique value, class breaks
• strong query tools
• legend and inset "overview" map
• adjustable measuring and scaling tools
• street address matching (one point at a time)
• pretty smart and very flexible labeling

ArcExplorer reads ESRI's Shapefile (.shp) format vector data, as well as several image formats including BMP, TIFF, and ERDAS.

Despite the feature-rich nature, ArcExplorer is relatively easy and quick to learn. And you can save your work as projects. This, combined with the hard-to-beat price, has made ArcExplorer a very popular method of distributing mapping technology across organizations and to the general public.

ArcExplorer's unique architecture enables the manipulation of local data (maps on your hard drive or server) as well as data on internet sites which serve maps via ESRI's Internet Map Server. You can not, at this time, mix and match local and internet maps in the same ArcExplorer view.

One of the cleverest features implemented is the integration of ArcExplorer with ESRI's ArcData On Line program. You can use ArcExplorer over the internet to manipulate maps at ArcData On Line; once you've gotten zoomed in on the data and the part of the country you want, a little "hard-drive" button allows you to purchase and download the data then and there!

And it's Free
The price is certainly right. ArcExplorer is free, and freely distributable. You can even use the product in commercial applications without royalty payments to ESRI. The only requirement ESRI imposes is that the ESRI logo be a part of any distribution of the product.

When you've used this product for a while, you realize that ArcExplorer has done a really excellent job at carrying out the "80/20" rule; implementing the 20% of the features that are most important to 80% of the users of desktop mapping. One is tempted to ask how ESRI could fiinancially justify giving away this core functionality. Of course, making data (and projects) created by ESRI software more accessible might help expand the market for ESRI software that supports and creates that data format (shapefiles). Nevertheless I suspect the original motivation, inside ESRI's programming team, was simply: "We can do this; this would be cool!"

ArcExplorer is built on ESRI's MapObjects, with additional OCX tools from software publishers VideoSoft, inner-media, and Data Dynamics.

The current version of ArcExplorer is 1.1, released in July of 1998. Version 2 is scheduled for release this summer. ESRI also plans to release a new ArcExplorer Java version this summer. And the upcoming release of MapObjects Version 2.0 will include ArcExplorer component building blocks - the MapObject source code used to build ArcExplorer.

ArcExplorer and the Illinois State Police
The Illinois State Police( ISP) views ArcExplorer as a critical part of their plans to extend GIS throughout their Agency. Lex Bitner, Assistant Bureau Chief of the Strategic Planning and Analysis Bureau of ISP, explained how ArcExplorer is used and why it was chosen.

"We have a lot of 'this is where things are' data," says Ms. Bitner. "For instance, information about crashes: fatal crashes, alcohol-related, teen-driver, and so forth." Distributing this information is critical, and printing and distributing paper maps is cost-prohibitive. So the Bureau puts the data in Project files and presses them onto CD-ROMs with a copy of ArcExplorer.

This system has been applied at four ISP district offices so far. "We make two or three site visits to determine the appropriate data. Then we do 1/2-day of training, and follow up a week or two later with another visit," Ms. Bitner explained. New data is delivered on a monthly or every-two-week basis.

Ms. Bitner says "ArcExplorer is something our users can learn quickly to get the information they need on a map. They don't need to become mapping experts."

The Illinois State Police started this ArcExplorer project in November of 1998. By distributing this "free" application, they intend to build support for the other mapping implementations they have in mind:

• internet mapping for community safety officers and the general public
• intranet mapping for the State Police, with more data
• installing ArcView for those State Police users who need advanced analysis, and, eventually …
• in-car mobile data computers.

The internet portion of this plan is set to go online within the next few days. ESRI's Internet Map Server will be used to deploy the same type of information presently on the ArcExplorer-based CD-ROMs.

ISP's use of ArcExplorer to "whet people's appetite for mapping," as Ms. Bitner puts it, is a powerful example of how "free" software can be used to promote the dissemination of broader and deeper GIS technology.

You can download ArcExplorer (an approximately 7 MB file) from the ESRI web page.