Trex

Question

Hello, 
 I am preparing a hydraulic model of a water distribution network in Epanet and my plan is to export the model to WaterGEMS and extract the nodes 
 elevation from the location DEM.My question is ,do i need to project the model or such in order to be in the same cordinates with the DEM or i can just export the model to WaterGEMS and extract the elevation without changing the coordinates.The DEM is in WGS 84 coordinate system. 
 Thanks

MPachlhofer · Accepted Answer

Simon, 
 
The problem with your shapefiles is they're only projected in geographic coordinate system of decimal degrees. The WaterGEMS model files were not created by drawing the network on top of the background files, so they can't be spatially aligned unless you project both in the same projected coordinate system that has units like meters or feet. 
 
Regards, 
Mark

Scott Kampa · Answer

Hello Simon, 
 
The model file and the elevation data file will need to have the same X:Y coordinates. One thing you can do is to load the file as a background layer (you may need to export this as a DXF or shapefile). If the file loaded as a background lines up with the model, you should be fine. If not, you would need to adjust the coordinates. 
 
The following link has information on this: communities.bentley.com/.../10115.error-when-using-trex-no-matching-data-all-elements-in-the-model-fall-outside-the-scope-of-the-dem . You can find general information on using TRex here: communities.bentley.com/.../8281.trex-terrain-extractor-tool . 
 
Regards, 
Scott

Sushma Choure · Answer

Hello Simon, 
 
When i tried to apply the shapefile you sent as the background layer in WaterGEMS model to check the co-ordinates , i got error as - "Tha shapefile is invalid or corrupt. " 
 
I couldn't open that shapefile in ArcGIS as well, getting error about feature class. Please check the shapefile.

MPachlhofer · Answer

Hi Simon, 
 Yes, you'll need to project the model file so it uses the same coordinate system as the DEM file if you want them to overlay in WaterGEMS standalone. You shouldn't have a problem extracting the node elevations from the DEM once they are overlaid. 
 The reason that Sushma was having a problem opening the file that you uploaded is because you're missing some essential files for the shapefile. Shapefiles need to have a .SHP, .DBF (which you uploaded), and a .SHX(which was not uploaded). The .PRJ file also helps because it contains the projected coordinate system and I see that was included in the upload. If you upload the .SHX file and you still need help one of us can have a look at your problem further. 
 If you're having trouble getting the WaterGEMS model to load in WaterGEMS for ArcMap for the first time please have a look at this wiki on " Opening a model in WaterGEMS for ArcMap for the First Time" 
 You might also want to have a look at this wiki technote on WaterGEMS for ArcGIS that answers the most frequently asked questions. 
 Regards, 
 Mark

Sushma Choure · Answer

Hello Simon, 
 Why don't directly start modeling in WaterGEMS? That will narrow down the problems and the conversion procedure. 
 You can then get the google earth image in the background in WaterGEMS. 
 If you have any civil product of Bentley , you can create DTM file by using that which can create the terrain model which can be used by TRex to extract the elevations. Please see below information. 
 http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/8281.trex-terrain-extractor-tool 
 http://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/12824.how-do-i-import-a-google-earth-image-so-it-lines-up-with-my-model

MPachlhofer · Answer

Simon, 
 
Sushma's suggestions will work, but if you know how project a shapefile or have a GIS/CAD proficient colleague that knows how, I would use that method because it will save you some time rather than redrawing the system. Below is a wiki that we have for projecting a coordinate system that I mean to include in my last post: 
 
 communities.bentley.com/.../12422.can-modelbuilder-or-loadbuilder-use-shapefiles-that-have-just-a-defined-geographic-coordinate-system 
 
Regards, 
Mark