"How Complicated Can It Be?"
The following text is Gil Castle's final draft of the
real estate column appearing in Business Geographics, March 1998
Copyright © 1998 GIS
During the five years that I've been writing the real estate column for Business Geographics, I've been very aware of the good-news-bad-news concerning the adoption of GIS by the real estate industry. The good news is that most real estate professionals have discovered GIS much more quickly than I anticipated—a validation of the relevance of this "location, location, location" technology to the needs of the industry. The bad news is that actual usage of the technology, especially in anyway approximating the sophistication in other fields, is lagging more than expected.
What's the problem? A full-blown GIS is undeniably complicated, requiring some level of understanding of software and data in the realms of cartography, spreadsheets, data base management systems, presentation graphics, Internet, etc. Though I believe that vendors have done a fairly decent job of making their products as "user friendly" as possible, learning and operating a GIS can nonetheless be time consuming and frustrating.
As a countermeasure, in my various lectures and workshops I find that an overview of GIS functions from simple to complex is helpful. Real estate professionals contemplating acquiring or already using a GIS thereby gain not only an understanding of what a GIS can do, but also a perspective on how much mental effort might be needed to exploit the technology's potential.
Accordingly, here is an outline of GIS functions ranked from the simplest to the most complex:
- Retrieving and displaying one or more maps (essentially just opening
a file, looking at the map, perhaps zooming in-out and scrolling-panning,
perhaps laying one map on top of another).
- Finding an address, the shortest route from A to B, adding simple annotation,
and similar options available at frequently visited mapping sites on the Internet.
- Retrieving certain types of information from the map by:
- Clicking on a map location to display attribute data about that
site, including text labels, numbers, photographs, other images;
- Selecting a pre-stored query from a menu to see a map of all sites
fulfilling the query's criteria, such as "all census tracts with a median
household income greater than $20,000 and an annual population growth
rate greater than one percent";
- Entering an ad hoc query, probably in an SQL-like format, again
to display all sites on the map fulfilling the user's specific criteria.
- Producing various types of thematic maps including:
- Shading polygons by different colors and patterns (e.g., census
tracts colored in five shades of green based on median household income);
- Using dot density functions (e.g., the number of dots placed in
each census tract is proportional to the population);
- Changing the width, color, and pattern of lines when thematically
mapping, say, traffic counts on a given city's arterials;
- Modifying the size, symbol, and color of individual points, such
a map of homes available for sale.
- Defining one or more regularly or irregularly shaped polygons (e.g.,
the primary, secondary, and tertiary trade areas of a retail outlet) and calculating
statistics about those polygons.
- Generating buffer zones and proximity calculations, such as all sales
"comps" within three miles of a subject property or within one mile of all
the freeway interchanges.
- Creating accurate, meaningful business graphics (bar charts, pie charts,
etc.) from mapped information.
- Importing and exporting tabular data from/to such widely used non-GIS
software packages as DBase, Excel, Lotus 1-2-3, Oracle, FoxPro, Paradox, etc.
- Developing real estate-specific models with outputs that can be mapped,
e.g., combining census tract-level data on the number of households and household
incomes into a retail buying power index.
- Employing network analysis functions, including:
- Finding the fastest and/or cheapest path from one one site to many
- Identifying the most efficient route connecting several destinations
(the "traveling salesman" problem).
- Accurately, completely, and efficiently geocoding (address matching)
properties on a map, such as all the locations of all the mortgages a bank
- Producing professional, compelling presentation graphics of cartographic
and related data, including the use of different colors, patterns, symbols,
fonts, raster images, layouts, etc.
- Storing and accurately registering to maps multiple types of raster
images, including simple photographs, high resolution aerial photography,
satellite data and videos.
- Digitizing (with a digitizing table or tablet) polygonal or linear features
not available from data vendors, such as proprietary submarket boundaries.
- Establishing and using real-time "hot links" (using DDE, OLE and other
protocols) between GIS and other software packages such as spreadsheets and
- Customizing a GIS with scripting languages provided by GIS vendors,
such as Avenue or MapBasic.
- Integrating third-party packages with the GIS, such as linking a GIS
to a Computer Aided Mass Appraisal (CAMA) package.
- Setting up pattern recognition modules (based on statistical and/or
artificial intelligence software) and "red flag agents" that search data bases
periodically for predefined circumstances, e.g., any new Class A office lease
A few caveats: The above list of functions does not begin to encompass all the functions available in GIS. Depending upon the particular GIS software employed, the ordering could change. Other observers would undoubtedly come up with a different ordering and even different classification system.
Hopefully, though, the above list will help both novice and expert real estate GIS users to determine where they are on the GIS learning curve, and the likely pay back of pushing onward.