GPS and GIS for Landscape Architects

By Leslie McGuire, regional editor

A vehicle GPS with a navigation screen is excellent for mapping large sites.

GPS was developed 20-years ago by the U.S. Department of Defense to keep a close watch on the rest of the world in an effort to maintain world peace.

Whether it?EUR??,,????'???s collecting physical data such as square footage, points, earth/material quantities, elevations, shapes, features, structures, water features, paths, roads and drainage facilities, or investigating natural systems such as wetlands, tree inventory, vegetation types, conditions or health of natural features, drainage, erosion control areas or mitigation areas, this technology has definitely become highly useful. Landscape architects need accurate information about any site for which they are developing plans.

Dots are turned into digital images using GIS with the addition of details from aerial photographs, CAD files or digital orthophotos.

At the present time, the Department of Defense has 27 satellites orbiting 11-thousand feet up. A backpack GPS receiver can take signals from four different satellites and calculate latitude, longitude and elevation. The data is then fed into a palmtop data recorder. A map of the area is constructed from the hundreds of readings showing the topography with accuracy to six inches, however this initial map is only a series of points. The details have to be added based on the mapper?EUR??,,????'???s records. This is where GIS comes in. Landscape architects as well as game developers have, over the years, developed thousands of digital images that can be adjusted for size, shape and color. GIS, as part of the process, turns the dots into a landscape giving the architect a rendition with real vegetation and real features. To design a site, aerial photographs can also be input. Any redesign can be done without getting out of the chair. Custom maps can start with a scaled hard copy map or be generated from electronic files such as CAD or digital orthophotos. Some applications may only need +/- 16 feet, obtainable from a hand-held GPS. Sub-meter mapping gives accurate X and Y coordinates within +/-36 inches. This works best for larger sites. For smaller sites, or landscape projects where accurate elevations in the Z-plane are desired or where absolute accuracy is required, sub centimeter mapping technology can be applied.

Anyone can purchase a receiver and hand-held computer and use GPS and GIS to do their own mapping. But the software can be a challenge to use if it isn?EUR??,,????'???t customized to the specific use the landscape architect needs. There are several companies that sell GPS devices. They range in price from $121.00 to $1800.00. Other companies provide GPS mapping services if an architect would rather work with an outside vendor: GEA or Golf Engineering Associates in Phoenix AZ and San Diego CA, Larry Rodgers Design Group in Lakewood CO, S.V. Moffett Company in West Henrietta N.Y., and Map Imaging in Omaha Nebraska.