Executive compass | February 2007
The year of terrain
Terrain, or as it’s more commonly known, elevation data or a digital terrain model (DTM), is one of those data sources that many people take for granted. Until recently, it was really only exploited in the GIS world for the flythroughs that made people sit up and take notice. Few people asked the questions, “Was it taken into account when my 2D vectors were captured?” or “What was the accuracy of the DTM which was used to make my orthophoto?”
Now, as more systems are becoming integrated and photogrammetry, mapping and GIS systems are sharing datasets, it’s apparent that we all have to pay more attention to how we create, handle and work with height information.
Automatic texturing: 3D city view Data courtesy of Simmons Aerofilms/Pictometry
In Europe, many SOCET SET® customers are working on making their country’s national terrain data set more accurate. Having more accurate height data also improves the quality of the orthophoto databases that are becoming a standard geospatial layer in many applications; the better the terrain is modeled, the better the removal of distortions due to height displacement and consequently, the more accurate the orthophotos. We’re finding that SOCET SET is helping out in many areas here. Automatic Terrain Extraction (ATE) techniques that use multi-pair and back matching are generating terrain models that require far less manual editing — higher accuracy and faster production times keep the production managers happy! Some editing is needed, though, and the broad range of tools available within the software makes that an efficient task, whether working on grids or TINs.
One of the challenges in building height models, however, is differentiating between the ground itself and what is on the surface, the DTM or the Digital Surface Model. To get to the true terrain (the ground), man-made objects and trees have to be removed, preferably automatically, and once again, the tools in SOCET SET are a great asset. For traditional orthophotos and terrain mobility analysis, bare earth (the DTM) is required. However, for new applications such as mobile telecommunications, airfield obstruction mapping, true orthophotos and 3D visualization, the Digital Surface Model is used.
Perspective view of terrain graphics
Finally, when it comes to advanced visualizations such as urban modeling, SOCET SET offers a unique range of tools. For complex buildings and features, the volumetric data capture tools of the Feature module allow the most amazing city models to be built, comprising complex shapes and structures. Currently, this tends to be done manually. However, our goal is to automate this as much as possible, so the new Next Generation Automatic Terrain Extraction (NGATE) product, with its ability to height every pixel and to create very good renditions of the surface model, will be extremely valuable to all our customers. NGATE is a quantum leap forward in automation.
I think the year ahead will be “the year of terrain.” Accuracy is key. With SOCET SET, we aim to help all of our customers produce the best terrain and surface models of all.
Cheers,
John Allan
Director of Sales and Marketing, EMEA
BAE Systems GXP