Miles Of Mapping

Hubertus says using the type of handheld GPS unit that is available at many retail stores to capture data for GIS did not provide the necessary accuracy–a fact that Hathaway, the GIS expert, discovered when trying to develop Endless Trails’ first maps using the data from the handheld units.

Hubertus recalls how time-consuming it was just to consolidate the various pieces of data into one shape file using GPS data from a handheld unit. “I did a 40-mile trail here in SteubenCounty, for instance,” he says. “In order to get it into a shape file and get it sent in for approval by the state–this was a brand new trail–I ran this through two software packages three times each. I probably spent close to two eight-hour days on my own.”

Upgrading Productivity And Accuracy

Enough was enough. Hubertus and Ball had an existing business relationship with Roy Boyd of Boyd Instrument and Supply Co. in Horsham, Penn., and spoke with him about what they needed to map the snowmobile trails. Because the area that they were mapping is quite hilly–typically up to 2,000 feet in elevation with valleys dropping to 900 feet–they needed equipment that would provide better accuracy than GPS alone. And since they would be plotting a tremendous amount of data, it would help if the data were more portable than with a handheld, over-the-counter GPS unit. Ball relates how he and Jason Ball, who works at his surveying firm, took a handheld unit and a laptop into the field to map a trail, and had to stop every 10 miles to download the GPS data into the laptop.

Hubertus had seen an advertisement for a commercial-capability handheld GPS receiver equipped with an integrated electronic compass, a digital camera and dual-constellation technology, meaning it could receive signals from both GPS and Glonass satellites, which provide better coverage on north-facing slopes. “I’m looking at this thing, and it was almost perfect for what we wanted,” says Hubertus. Boyd gave Hubertus and Ball a demonstration of the Topcon GMS-2 unit, and they were encouraged to find they could also use a software program called TopPad–ESRI’s ArcPad with a Topcon tool bar that works in shape files. “That eliminates working through a lot of different programs,” notes Hubertus.

The two contacted Hathaway about their new purchase, and let the GIS expert try it out. “Steve and Jim gave it to me to play with and see what I could do, to see what makes it tick and not tick,” says Hathaway. “I have a couple of buddies here in SteubenCounty who gave me permission to ride close to 1,000 acres of fields and streams and roads and gullies.” Hathaway first uploaded aerial photos from the New York State Office for Technology’s New York State GIS Clearinghouse and, while riding into a canyon and against a few north-facing slopes with heavy hemlock tree cover, verified his locations on the aerial maps using the new unit and an external PGA-5 antenna.

The antenna can be mounted on a utility terrain vehicle or work snowmobile. The antenna and a BR-1 Beacon Receiver that accesses the Coast Guard Beacon real-time correction service provide Endless Trails with higher data accuracy than with the handheld unit alone because the system utilizes a second correction service in addition to the Wide Area Augmentation System (WAAS) signal correction. Boyd notes that this combination allows the trio to achieve sub-meter accuracy on its trail maps. “From a trail aspect, it’s a lot tighter than you need, but it’s better to have it that way than the other way,” Hubertus says.

They really noticed a quantum leap in productivity from the portability of their collected location data as they mapped Allegany, Steuben and Delaware county trails from September 2006 to April 2007. “As long as we had an SD [secure digital] memory card and we were getting good satellite coverage, it was nothing for us to utilize the unit in whatever conditions we were in,” says Ball. “I think one day we had a 70-mile trail location.” Hathaway adds, “We are able to gather that information and put it right onto a card. You can put another card in and keep riding.”

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