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Geographic Information Systems (GIS) are spreading across the globe like wildfire. The range of applications for GIS is wide and diverse, including urban planning, land development, emergency services and response (911), watershed analysis, earth science studies, population statistics--the list goes on. However, these systems are only as good as the information put in them.
Fortunately, acquiring base map information for GIS has become easier through improvements in aerial photography and the availability of digital-ortho USGS quad sheets. Obtaining mapping location and attribute information for features in a GIS is the biggest challenge many agencies face in creating and maintaining comprehensive databases. The accuracy required of this data for positions varies greatly. For example, in urban planning and emergency response, meter accuracy is more than sufficient. But for municipal wastewater systems, accuracies of one centimeter are necessary.
To obtain the necessary accuracy of data for specific purposes like GIS, the right tool must be used. Revolutionary products offered in today's market are created by innovatively combining technologies in a new way. These products provide unique solutions, expediting the execution of routine tasks with speed, accuracy and efficiency. Topcon Positioning Systems of Livermore, Calif., recently introduced an innovative product for data collection: the GMS-2 handheld GPS receiver/GIS mapping device/field controller. This new instrument enables rapid collection and maintenance of GIS locations and attributes, and also functions as a field computer for survey tasks. Two users share their experiences with us.
New Solution for GIS Data CollectionTopcon's GMS-2 incorporates a digital camera and electronic compass in a small, handheld GPS+GLONASS receiver. An image of a mapped feature can be captured and tied to GPS coordinates, compass bearing and attribute data.
To accommodate a wide variety of data collection tasks, the instrument features several receiver options. With the standard WAAS (Wide Area Augmentation System) correction, it can be used as a stand-alone GIS mapping receiver achieving meter-level accuracy. When the optional access to the Coast Guard Beacon Differential GPS Service is available, the GMS-2 will provide DGPS correction for submeter accuracy. With an optional external L1 antenna, the GMS-2 can perform post-processed static survey tasks with less than 1 cm accuracy.
The GMS-2 provides 50-channel tracking capability for both GPS and GLONASS satellites with Topcon's TPSCORE chip technology. Access to both satellite constellations can provide more robust tracking capabilities, improved precision and enhanced operation in areas with obstructed sky views.
Several software options are available to extend the GMS-2's capabilities into a wide range of applications. With Topcon's TopSURV field controller software, the unit can be configured for use as a field controller with total stations and RTK GPS systems. With field controller TopPAD field mapping and management software, the GMS-2 functions as a GIS data collection and maintenance tool. TopPAD is a mobile GIS field data collection software co-developed with ESRI (Redlands, Calif.) that combines the power of ESRI ArcPad with a special user interface that supports Topcon hardware products.
The innovative capabilities of the GMS-2 bridge the gap between GIS and land surveying, providing a solution for a wide range of tasks spanning both disciplines. The following case studies of a civil engineer for a municipal utility and a forest product producer just begin to reveal the broad scope of potential applications.
Locating Water System InstallationsA few years ago, several agencies of Limestone County in northern Alabama expressed an interest in an integrated GIS network. In 2003, a GIS committee (the Athens/Limestone County GIS Consortium) was formed to oversee the creation of a cooperative geodatabase, ensure a seamless exchange of data, and reduce implementation costs for each participant.
One of the agencies involved in the project, Athens Utilities, owns and operates multiple services for the city of Athens and outlying areas. Subsidiary departments manage natural gas and electric systems. Another subsidiary department, the Water Services Department, is responsible for the operation, maintenance and expansion of water and wastewater facilities.
Jonathan Bedsole, staff engineer for the Water Services Department, is primarily responsible for designing expansions, reviewing site development plans, inspecting new installations during construction and tracking as-built information. When the GIS consortium was formed, Bedsole was assigned the responsibility of creating a GIS database for the systems under his jurisdiction. Mapping existing features for the initial database represented a sizable challenge. Myriad lines, valves, hydrants, manholes, pump stations and treatment plants serve approximately 9,500 water and 5,200 wastewater customers. Additionally, a new certification process begun by the Athens Fire Department this past April (the Insurance Services Office certification) requires Bedsole to ensure the proper fire insurance ratings are applied. To do this, he was asked to provide locations and flow rates of all hydrants. But the hydrant information in the city's GIS database was incomplete. With Bedsole's workload and multiple responsibilities, he had logged only 75 hydrants.
To meet the needs of Athens agencies, Bedsole needed a reliable and robust GPS/GIS unit to accurately map feature locations and attributes. He soon acquired a Topcon GMS-2 from Roger Wheeler, technical sales representative of Hayes Instrument Company in Shelbyville, Tenn. He worked on the project in short segments as often as his busy schedule allowed and collected data on more than 250 hydrants in a period of three weeks.
Bedsole explained that the GMS-2 was a perfect solution for his needs. "For mapping fire hydrants, the submeter accuracy level of WAAS-corrected DGPS is perfect," he says. "The 1.4 psi difference in flow rates within the distance of one meter is negligible when working with pressures in the 50 to 70 psi range and can be discounted.
"The real benefit is that I don't need to set up my RTK GPS system to start logging installations," Bedsole continues. "If I have 30 minutes between other responsibilities, I can just grab the GMS-2 and head out to the field. I can collect a considerable amount of data in the time it would take me to set up and take down the RTK system. I've been able to collect 40 hydrants in one and a half hours."
Bedsole has extensive experience in field surveying for easements, line locations and as-builts, and prefers to use TopSURV for obtaining location data. To enable simultaneous logging of attribute data and position coordinates, Bedsole uses Topcon's TopPAD software and the GMS-2. With this combination, he can work in a native Shape file format and import data directly into the geodatabase.
Bedsole also uses the Water Services Department's Topcon GTS-235W total station and HiPer Lite RTK GPS system for locating property corners, staking easements and acquiring as-built information on sanitary sewer installation. Prior to obtaining a GIS data collection instrument, he used the HiPer Lite for these tasks. Using the GMS-2 as a field computer, Bedsole is able to connect wirelessly via Bluetooth to both of these instruments. All of his survey, GPS and GIS data can be managed with one instrument.
Managing TimberlandsRoseburg Forest Products (RFP), the third largest closely held forest products company in western North America, manufactures a wide range of building materials, including dimensional lumber, plywood, paneling and other specialty items. To meet the constant demand for raw materials, RFP owns and manages 750,000 acres of forest land in southern Oregon and Northern California.
Mapping is an essential tool of timber management. A GIS database was implemented in 1996 to consolidate and coordinate data for the California timber tracts. Originally, the base layer was created by hand-digitizing USGS quad sheets. Today, aerial photos and digital ortho quad sheets make the acquisition of base data much simpler.
Arne Hultgren, a registered professional forester and planning manager for Roseburg Resources, California division, explains the importance of Roseburg's mapping database. "Just about everything we do is tied to a map and consequently to the GIS system," he says. "Everything we do pivots around our GIS so critically."
Roseburg's GIS database also provides asset management functions. "Our timberlands are 90 percent of the company's value," Hultgren says. "It's very important to document where all of our assets are. Our primary asset is trees, but there is also value in our land, roads, drainage structures, culverts and bridges."
For the forest industry, compliance with environmental regulations is an inescapable obligation. California's timber harvest regulations are particularly stringent; detailed environmental impact reports and explicit disclosure of all harvesting activities are required for permitting operations. To properly prepare the permit applications, accurate locations and detailed information about streams, culverts, archeological sites, endangered birds' nests, wildlife activities and other environmentally significant information must be maintained. Roseburg's GIS database serves as a repository for this critical data, and its collection required a robust and reliable tool.
Searching for the Right ToolHultgren and his staff searched for a tool that could provide precise locations and log object data for all the forest features. He experimented with recreational-type GPS handheld units to get rough positions within a 60-foot radius. The major drawbacks to this type of instrument are poor accuracy and the inability to produce satisfactory results under heavy tree canopy. Backpack GIS units with external antennas were not considered because of their bulkiness and likeliness to be snagged in underbrush.
Hultgren learned about Topcon's GMS-2 device from Ben Folger, sales manager for Topcon California. He immediately saw several advantages. Fifty-channel dual-constellation satellite tracking--GPS and GLONASS--can provide improved accuracy and enable operation under heavy tree canopies. The DGPS function, which obtains WAAS corrections, provides improved meter-level accuracy, which is perfect for forestry applications.
Hultgren obtained a GMS-2 and put the unit through several weeks of heavy use in a wide variety of applications. The GMS-2 has enabled Roseburg's field personnel to collect all required data about a mapped object with a single instrument. This is a huge benefit, considering the large amount of gear carried on a forest reconnaissance mission. With the GMS-2, the need for a separate camera and compass is eliminated. Object attributes can be entered in TopPAD right on the GMS-2, eliminating the need for detailed field notes.
To comply with environmental impact reporting requirements, Roseburg Resources must file a report on the condition of each watercourse crossing every two years. These crossings range from simple 18-inch corrugated metal pipes to 70-foot bridge spans. Keeping track of several thousand installations in remote locations over 285,000 acres is a time-consuming chore.
Hultgren found that the GMS-2 expedited the tracking of these installations. "We can locate drainage structures from the digital image and get an idea of why they failed," he explains. "We may have a crossing that has a chronic failure on it. Being able to see images of the installation over subsequent years gives us the ability to think about changing the design, or putting in a larger pipe, different end treatment or different rock slope protection." It also helps the repair contractor understand what materials and equipment will be required before heading into remote areas.
RFP manages timber harvest operations in 20-acre units. Typically, these units are defined by roads, property lines, streams and geographic features. Initially, these boundaries were located with rudimentary methods, sketched by hand in the field and entered into the GIS database. But this caused costly errors in mapping procedures. "If you're dealing with a harvest unit where the value of the timber may be in excess of $20,000 per acre, the miscalculation of an acre is a fairly significant event that you don't want to occur," Hultgren says.
"The GMS-2 allows us to accurately record not only the shapes of the units, but also habitat retention areas," he continues. "These are important wildlife legacy structures. Now we are able to monitor these areas as the harvested stand grows back. We will be able to record the impact and how wildlife uses those particular habitat retention areas."
Following his rigorous evaluation, Hultgren is pleased with the performance of the GMS-2. "The ability to capture images of features without carrying a separate camera and integrating them with GIS attributes is a tremendous advantage to Roseburg," he says. "The seamless WAAS correction that Topcon incorporated into the unit is really incredible. I'm getting horizontal accuracies of less than one foot, which is excellent for our purposes. The GMS-2 is not just a GPS data collector--it's so much more."