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Automatically assign ground elevation data to nodes using the TRex Terrain Extractor tool.
The Terrain Extractor (TRex) tool can automatically assign elevations to any nodes based on the nearest elevations from a contour DXF, shapefile, LandXML file, or spot elevations. If you are working in WaterGEMS, SewerGEMS, or HAMMER in the ArcGIS environment, there is the additional ability to assign elevation data based on Raster, TIN and DEM files. Nodes can include junction, hydrants, pumps, tanks, reservoirs, and valves. NOTE: Tank elevation or level range will not be included with TRex, only the ground elevation.
You can access TRex from the Tools menu. Most options are self explanatory, but the most important thing is that the contour must line up with the elements in the model. Meaning, the contour must spatially overlap the model, with both the model elements and the contours in the correct X:Y coordinates.
If you want to apply elevation data for a selection of nodes instead of the whole system, choose the Selection or Selection Set radials in the section "Nodes to Update". For Selection, it will apply data to elements you have already selected in the drawing. For Selection Set, you can choose a selection set of elements to apply the data.
Standalone
ArcMap:
Note: When using TRex, it is necessary that the model and the DEM be in the same coordinate system. Usually the USGS DEMs are in the UTM (Universal Transverse Mercator) with North American Datum 1983 (NAD83) in meters, although some may use NAD27. Models are often constructed using a state plane coordinate system in feet. Either the model or DEM must be converted so that the two are in the same coordinate system for TRex to work. Similarly, the vertical datum for USGS is based on national Vertical Geodetic Datum of 1929. If the utility has used some other datum for vertical control, then these differences need to be reconciled.
The Bentley Civil products can create a terrain model from Google Earth data. If you have access to InRoads or Power Civil for example, you can create the terrain model using that product, as detailed here:
Create an InRoads DTM from Google EarthThis will create a .dtm file, which the Terrain Extractor tool can read, if you choose the Bentley DTM File option as the source data.
Starting with the SELECTseries 5 release of the Storm and Sewer products, a new Terrain Model feature has been added, which allows you to activate a terrain model file in the model at all times. Elevations of nodes will then update automatically per the active terrain model, when the nodes are added or moved. For more on this, see the Help topic or the following articles:
What's new in SewerGEMS V8i SELECTseries 5?
What's new in SewerCAD V8i SELECTseries 5?
What's new in StormCAD V8i SELECTseries 5?
What's new in CivilStorm V8i SELECTseries 5?
Please refer to this article:
Interpolation Method Used by Terrain Extractor (Trex)