How do I determine what projection a model has been set to?

Product(s): WaterGEMS, SewerGEMS, HAMMER
Version(s): 08.11.XX.XX, 10.XX.XX.XX
Area: Layout and Input

Problem

How do I determine what projection, coordinate system or spatial reference a model has been set to? For example I have received a WaterGEMS model from another consultant and need to figure out what coordinate system it is in.

Solution

The software itself is not aware of the coordinate system (spatial reference) - it simply knows the X and Y coordinates of each node in the network. If the spatial reference has not been typed in under File > Options > Hydraulic Model (for ProjectWise purposes), then it is not possible to determine the coordinate system. In this case it is best to contact the person who built the model as they may have this information.

If you are working in the ArcGIS integrated platform, you can use the following steps:

1) Load the layer in ArcMAP.

 2) Right click on it, in the Table of Contents (layers) and go to the properties.

 3) On the source tab, it should say what the projected coordinate system is and what geographic coordinate system the model is in.

 4) If it says it is undefined, then in the catalog you will have to place the file in the tree view on the left and left click on it to highlight it and view the contents.

 5) When you do this, there are 3 tabs. Click on the metadata tab and then within that there are another 3 tabs. Click on the Spatial tab.

 6) If there is still no coordinate system in that tab, then you can try to look on the description tab and try to find out where the data came from.

Data Export Considerations

When exporting model data to external formats such as DXF or Shapefile, the spatial reference will not be exported, since as explained above, the software is not aware of the spatial reference. For example a .PRJ file will not be included with a shapefile exported from Flextables, and if you try to use the shapefile in another application that requires everything to be in a projected coordinate system, you will encounter an error about missing spatial reference or missing coordinate system. In this case, you will need to define it in the generated file. For example you could use the "Define Projection" tool in ArcToolBox, which may also enable you to import the spatial reference from another, existing file (so you can for example match up the coordinate system to another file you want to use it with).

See Also

WaterGEMS For ArcGIS [FAQ] 

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