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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, spot elevations or a raster/dem. Note that in order to use a raster/DEM, you will need to be using WaterGEMS within the ArcGIS platform. 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 junctions in the model. Meaning, the contour must spatially overlap the model, with both the junctions and the contours in the correct 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.
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.