Location, Location, Location
July 6, 2011
When the City of Chattanooga mapping project in Tennessee went out for proposals in 2007, Dixie Brackett of Earthworx Inc. knew she and her firm would be up against many large consultants trying to win the project. She also knew she was venturing into territory that most land survey companies were unfamiliar with: mapping projects with deliverables in Esri.
Nevertheless, she had a few advantages that set her apart. She owned copies of Esri ArcView and ArcMap; she owned Carlson SurvCE, a field product with full GIS capabilities that could output Esri shapefiles; and she had staff familiar with these products and how to link the data from the field into Esri. Brackett submitted her bid for the storm sewer mapping project and won. And then she did something even more unusual--she delivered the project ahead of schedule and with accuracies that exceeded specifications. This project promptly set Earthworx on a course of growth driven largely by GIS-related mapping. Earthworx grew by 32 percent in the recession year of 2009 and won the Esri Special Achievement in GIS (SAG) Award in 2010.
Earthworx was in the vanguard of a new movement in GIS: accurate GIS mapping. The Earthworx field crews entered all the necessary GIS attribute data for the storm sewer system--including the pipe diameters, pipe material, depth of manholes, etc. But because of her background in traditional land surveying, Brackett directed the crews to measure the Chattanooga sewer systems with total stations and RTK GPS as opposed to low-accuracy, differential GPS systems. Accurate measurement of flow line elevations and pipe alignments provides added information for stormwater modeling and for precise field location for repairs and upgrades. Now the GIS industry is beginning to demand the very thing Earthworx provided as a fringe benefit--accuracy. The surveying profession has never been better positioned to enter the GIS market because surveyors understand accuracy and have the technology to provide it.
Since the origins of GIS, land surveyors and GIS professionals have been separated by a gaping chasm that still remains. GIS professionals often pull back when they hear the term “survey,” and too few professional land surveyors have familiarized themselves with the concept of line and point attributes and mapping in Esri, the common platform for GIS.
Meanwhile, the tools that link the two markets are changing quickly. For years, the shapefile was used to link to Esri products. Data collection programs like Carlson’s SurvCE and Esri’s ArcPad (the most commonly used field GIS product) would export shapefiles, which then could be imported within Esri products. But the link was essentially crude, in that distinct shapefiles had to be made for points, linework and polygons, the three building blocks of mapping within Esri software. Additionally, shapefiles often had to be converted from one coordinate system to another (from UTM to NAD83, for example, or from metric to U.S. feet) so that base maps matched, and this conversion presented a challenge.
In recent years, Esri has begun to promote other methods besides shapefiles for file linkage. One method embeds all Esri drawing elements and associated attribute data in a .dwg file that Esri will export (through an “Export to CAD” option, available in ArcMap 9.3.1 or later). Field products such as SurvCE and SurvPC, Carlson’s data collection program for PCs, can now read the Esri-defined MCS data format in the .dwg file and extract all GIS prompting automatically. Then, after field data collection is completed, the drawing can be exported and read back into the Esri map with all the new attributing included. This process also uses a conventional .dwg file as the link, as opposed to a shapefile.
Another method of fieldwork lets users literally “live” in the Esri environment, working and storing data directly in the Esri map without importing or exporting. As long as a license is available for ArcView or ArcMap, or embedded in SurvPC itself, SurvPC will load and directly display the Esri drawing, capturing the official GIS prompting within the Esri MXD file. Still another approach is to run survey commands from within ArcMap 9.3.1.
All these methods of linking to Esri have evolved since Earthworx engaged in the Chattanooga storm sewer mapping project in 2008. The resulting information is proving increasingly valuable to utilities and communities.
In the absence of good mapping, the primary method for locating buried utilities of all types is the use of utility locators. By using locators in conjunction with SurvGIS, a simplified GIS program that includes links to a variety of cable and utility detectors, a point can be stored when the utility is detected. With multiple points, portions of the utility lines can be drawn using field coding. This process is useful for mapping and for utility location prior to construction or repair.
However, in an emergency such as a water main break, time is of the essence in locating and repairing the source of the problem; there might not be time to “localize” and start up traditional GPS locators. By using an iPhone with SurvGIS,* a simplified GIS program that includes links to a variety of cable and utility detectors, field workers can literally view water mains and other utilities superimposed on the screen and walk right up to them in preparation for repair work or field verification. Using the same program, crews can record the information and also take and store associated photographs with the updated data. The end result can be exported back to Esri using the .dwg data linkage method. Alternately, software such as Carlson SurvPC can be used to map and fully attribute the improvements.
The field techniques for GIS mapping are evolving quickly. Companies like Earthworx are the early pioneers in accurate GIS mapping. Now, with techniques like augmented reality and photo-linked attributing, land survey firms can provide even more valuable services to the GIS industry and tap new sources of growth.
*At press time, SurvGIS was still under development with the release date to be determined.