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GIS

Third-Party Solutions Enhance Data Transfer

1 Sep, 2008 By: Andrew G. Roe,P.E.

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New software improves efficiency of data updating and provides an ongoing log of edits and updates.

While major CAD and GIS software vendors have improved data exchange processes in recent years, the quest for true interoperability remains somewhat elusive. CAD users seeking to import GIS data must often perform multiple steps to organize data in a usable manner, and GIS users face similar scenarios when importing CAD data.

To bridge the gap, many end users have turned to third-party solutions. The city of Turlock, California, for example, often shares data between engineering and utility maintenance departments to update sewer and other infrastructure data. In the dark ages before GIS and CAD software shared data, field personnel would mark up hard-copy maps to identify lines that were abandoned or needing maintenance, then pass along the information to engineering staff, who would update CAD drawings accordingly. As import/export capabilities of CAD and GIS software improved, electronic data transfer became more practical, but hitches remained. GIS information was often not organized in the proper CAD layers, and attributes such as sewer line conditions were not easily transferred into usable formats.

The city began using FME software from Vancouver, BC-based Safe Software to smooth the process. Utility personnel now add data to GIS mapping using an Autodesk MapGuide interface, which stores the geometry as SDF files and associated attributes in Microsoft SQL Server. These data files are then processed by FME Workbench, which performs logical joining of data and creates DWG files readable by AutoCAD Map 3D. Field notes and other pertinent information about individual sewer lines are saved as object data, with attributes for each line.

In addition to improving efficiency of data updating, the FME processing provides an ongoing log of edits and updates. "It allows everyone to take ownership of their data," said Dan Lourenco, information technology analyst with the city. The electronic updates help users clearly understand what changes have been made and when they were completed, according to Lourenco.

The ability to read and write Map 3D object data was added in the 2008 release of FME Desktop, which contains the Workbench authoring module and others for extracting, translating, and loading data -- collectively called ETL. Previous FME versions could also transform MapGuide data into an AutoCAD format, but without conveying attribute data. The process works in a similar manner for converting CAD data to a GIS format, and can be closely monitored by users to control how data is formatted in the destination file.

In addition to MapGuide and AutoCAD data, FME works with more than 200 other GIS, CAD, raster, and database formats. Safe Software, founded in 1993, coined its name from a data format called the Spatial Archive and Interchange Format (SAIF), which was primarily used in British Columbia and is similar to today's more universal model, Geography Markup Language (GML).

In the early days of GIS-CAD data exchange, "you had to be a programmer" to control the process, said Dale Lutz, Safe Software cofounder and vice-president of development. With FME's interface, users can select from menus and dialog boxes to rearrange and restructure geometry, layers, and other settings. Access to FME objects for further customization is also available to programmers working in Visual Basic, C, C++, C#, Java, .Net, Python, and Delphi languages, but Lutz estimates less than 10% of FME customers actually perform custom programming.

The 2008 version of FME also added support for building information modeling (BIM) and other 3D data. "There seemed to be a repeated need to cross the GIS-BIM divide," noted Lutz. With BIM support, GIS professionals can integrate actual building information such as doors, windows, and walls into their planning and mapping data. Supported formats include Adobe 3D PDF, CityGML, LandXML, and Industry Foundation Class (IFC) STEP Files. Lutz sees BIM as a major growth area for FME. "We're just starting in this journey," he said.

In addition to FME Desktop, Safe Software offers FME Server for distributing spatial data over the Web. FME Server users can create an online download service that allows anyone with a Web browser to request spatial data in the format and projection of their choice. Users can dynamically transform spatial data into formats like KML (Google Earth), GeoRSS, and GeoJSON, as well as several raster formats, then stream the resulting data set directly into theWeb.