A Gaggle of Google Earth Tools6 Nov, 2006 By: Andrew G. Roe,P.E.
Users have a host of new options for publishing CAD and GIS data to this popular mapping tool
In the past few months, CAD and GIS users seeking to link project data with Google Earth mapping data have found new and powerful tools at their disposal. Autodesk and Bentley have both introduced tools for connecting their CAD products to Google Earth, and other vendors are also throwing their hats into the ring.
After Autodesk introduced an AutoCAD add-on application for publishing and viewing drawings and 3D models within Google Earth, the company released an Autodesk Civil 3D extension that allows engineers and surveyors to publish intelligent Civil 3D objects such as points, parcels, alignments, corridor models, surfaces and hydraulic networks in a Google Earth environment. Using a wizard-based interface, the extension guides users through a process of selecting which objects to publish and automatically positions the objects on a Google Earth background, assuming the project's coordinate system is properly georeferenced.
Georeferenced AutoCAD and Civil 3D models can be published to the Google Earth environment for impressive visualizations. (Image courtesy of Autodesk)
To georeference a project, simply use the wizard to specify the coordinate system or drawing coordinates that will be mapped to the Google Earth coordinate system. You can select either a coordinate system or a reference point in a drawing and assign it a latitude and longitude that will be transformed to the Google Earth coordinate system.
Short of accurately georeferencing project coordinate systems, users can grab mapping data from Google Earth, bring the data into AutoCAD or Civil 3D, add design information, then publish everything back to the Google Earth environment. The process is not suited for final design quality, but it can yield nice-looking conceptual drawings. To run the Civil 3D extension, you need Civil 3D Service Pack 2 in addition to the Google Earth extension. Both the AutoCAD and Civil 3D extensions are currently offered as free preview products, with no guarantees as to suitability for real-life projects.
Bentley's Google Earth tools offer similar capabilities, enabling MicroStation users to publish 3D CAD models to the Google Earth environment, albeit without extended discipline-specific object data. MicroStation files placed in the Google Earth environment can also comprise links to other data sources such as spreadsheets, photographs, additional drawing files and URLs -- enabling peripheral project information to be shared through the Google Earth interface. Embedded links within a MicroStation file are automatically published as Google Earth Placemarks.
MicroStation drawings can include links to other data sources in the Google Earth environment. (Image courtesy of Bentley Systems)
Like the Autodesk products, Bentley's tool publishes drawing files to a KML (Keyhole Markup Language) format. Levels available to the MicroStation user are maintained in the KML file, so the Google Earth user can turn parts of the model on and off. Saved views in MicroStation are transferred to the KML file, so the Google Earth viewer can move through preconfigured perspectives in the model and navigate to supporting project data.
In addition to the CAD heavyweights, other vendors have introduced Google Earth add-ons in recent months. Baltimore-based CAD reseller Avatech Solutions offers a plugin called Earth Connector, which allows users to place 2D and 3D entities from AutoCAD-based products directly into the Google Earth environment. The product works with plain-vanilla AutoCAD, as well as Architectural Desktop, Map 3D, Civil 3D and Land Desktop, using Map 3D's coordinate transformation engine to convert coordinates into Google Earth's coordinate system, and a wizard-based process to create a georeferenced KML file. It also enables Autodesk Revit users to publish BIM (building information modeling) data to Google Earth, and to share data such as part numbers on doors and windows, or square footage on walls and floors.
RDV Systems, an Israel-based developer of visualization software for use with Autodesk Civil 3D, Map 3D and Land Desktop, also recently added Google Earth-publishing capability. Users can produce fly-through animations in Google Earth by defining placemarks and assigning latitude, longitude and altitude to alignment points. RDV Systems offers a free 30-day evaluation download of the software .
MWH Soft, a Broomfield, Colorado, subsidiary of the AE firm MWH Global, recently launched NetVIEW, an Arc-GIS application that displays GIS data and modeling results in Google Earth. Initially introduced for InfoWater, MWH's water distribution modeling and optimization application, NetVIEW can display water distribution network models in Google Earth with detailed hydraulic data, such as flow and pressure values, as well as water-quality modeling results. Built using Component and XML technologies, NetVIEW is available on a subscription basis for $2,000.
The options for tapping into Google Earth's capabilities are clearly growing, and will no doubt continue to do so. As with any new technology, however, users should proceed with caution and remember that a pretty picture does not necessarily equate to an accurate design.