Seattle, Washington, Makes Maps More Accessible and Useful

Maps R Us

As a cosmopolitan area experiencing explosive growth, the City of Seattle needs maps, lots of maps. With growth comes change, and maps require constant updating to be useful. The City of Seattle Public Utilities' GIS group is charged with maintaining, updating, and serving up maps for the City.

According to Vicki Evans, GIS products and services manager for Seattle Public Utilities' GIS section, meeting the demand for maps for analytical and reference purposes through the City's Intranet and providing public access through a Web site were difficult tasks due to the huge amount of digital information contained within GIS map files. Although delivering maps in digital form improves currency and cuts down on paper waste, these maps were still slow to load and therefore awkward to use. Seattle Public Utilities could not adequately meet its goal of providing easier access to GIS maps for both users within the City government and the public until a solution was found.

The solution was found in Esri's ArcInfo software, then Seattle Public Utilities began to use it to build maps, converting the data into visual form.

GIS technology has replaced many paper-based manual mapping processes. "The moment you print the map, it's out of date," says Evans. GIS, on the other hand, offers real-time, up-to-the-minute information for a rapidly growing City.

Serving Up Maps

Seattle Public Utilities' GIS section performs three primary functions. First of all, the GIS section provides the foundation for the City's GIS activities, the GIS databases that are shared for all City functions, according to Evans. Most of the City's departments use GIS maps and need maps for a variety of functions: for example, to show property ownership, topography, or aerial photography. Most departments have their own GIS, but use the base layers maintained by Seattle Public Utilities' GIS group as the foundation for what they do.

Secondly, Seattle Public Utilities has its own GIS function to maintain the data and applications that support utility management functions such as the sewer and drainage infrastructure and water distribution.

Finally, the GIS department of Seattle Public Utilities provides GIS products and mapping and data provision services to the Business community and public. "In the past, people used a program like AutoCAD and started from scratch to build the data they needed," says Evans. Providing these products and services reduces duplication of effort and cuts costs for everyone.

Within the City government, there are two internal platforms for distribution of GIS maps-the City's Intranet and desktop users-and the GIS department serves both. Desktop users within the City government use Esri's ArcView GIS, which allows non-GIS professionals to use GIS for analysis and mapping on their own desktops.

There is a huge demand for quick and easy use of map images, and one of the goals of Seattle Public Utilities' GIS department was to make GIS technology more easily accessible to the non-GIS professionals within City government.

First, however, Seattle Public Utilities had to figure out how to deal with the huge and therefore slow-to-draw file sizes of GIS maps.

A secondary goal is to make GIS maps more available to the public. According to Evans, one of the GIS group's short-term plans is to publish GIS maps for public access via the Public Access Network, known as PAN to City employees (www.pan.ci.seattle.wa.us). This will not only make the GIS maps more available, but it will cut the City's costs to respond to requests for maps.

Image Compression Is the Answer

Until recently, there was no efficient way to serve complete, reasonably sized digital maps to customers both within and outside of City government. "The maps were just too big to publish even in our digital world," says Evans. Too big, meaning if the images were reduced in size, they lost resolution. If they were not reduced in size, they were too slow and cumbersome to load and ate up disk storage space. Seattle Public Utilities solved the problem of huge, unwieldy images by using MrSID Portable Image Format technology from LizardTech (www.lizardtech.com).

MrSID integrates with GIS software to compress finished images and convert them to a workable size. The technology enables faster downloads, but also retains detail due to a pixels-on-demand process that delivers only the amount of information necessary for the size and portion of the image being viewed. When zooming in on the image, the additional pixels are called up so resolution stays clear rather than becoming pixelated.

MrSID can also append many images together into one image. This is particularly useful with aerial photography because otherwise the photographs are viewed as a mosaic of images, which makes them very slow and awkward to work with.

Using MrSID image compression technology is enabling Seattle Public Utilities to meet its goal of easier accessibility to GIS. "Another benefit of using MrSID is that the cost of serving the user community both in staff time and paper costs has been reduced because the GIS department is not constantly reprinting maps," says Evans.

Seattle Public Utilities has found MrSID useful for other purposes, too. Within the GIS group, GIS systems analyst Harvey Kocher, together with Richard Folsom, leads the Applications Development team, a dozen geographic analysts who create software for producing map products or performing complex geographic map analysis. Kocher says they are just starting to integrate MrSID into the custom mapping software that they are creating.

"When building applications that include GIS maps, the developers want to optimize the performance and quality of the maps that are being served to the users," says Kocher. By creating the cartography ahead of time with ArcInfo, then converting it to MrSID format, the application performance is increased. "This allows us to get a more attractive image on the screen," he explains.

According to Kocher, users can't tell that anything is different with the MrSID compressed images. The GIS group maintains both the original images and the compressed images on its systems. It also uses MrSID for creating printed copies of digital maps.

Seattle Public Utilities bought both UNIX and Windows NT versions of MrSID. The UNIX version was integrated into existing programs that automate the compression of a large number of images. These programs generate maps from GIS data in ArcInfo and then use a MrSID command to convert and compress the maps into MrSID format.

For more information, contact Vicki Evans or Harvey Kocher, Seattle Public Utilities (tel.: 206-684-8857). (A somewhat longer version of this article first appeared in the October 1999 issue of Puget Sound Computer User. Reprinted with permission from the October 1999 issue of Puget Sound Computer User. Copyright � 1999 KFH Publications, Inc.)

ArcNews home page