Converting a 3D UGrid in GMS

Have you ever had an unstructured grid (UGrid) or mesh in your project in the Groundwater Modeling System (GMS) that you want to convert to another geometry? While there isn't a specific tool for converting UGrids in GMS, it can still be achieved by following a few simple steps. Typically a UGrid will need to be converted to a scatter set and from there the scatter set can be converted to other geometries. Converting UGrids or mesh into scatter points can be a good way to compare data between models, especially if one of the models is older and doesn't, or can't, include a UGrid or mesh. If this is something that interests you, this article will explain how to get from a UGrid or mesh to either 2D or 3D scatter points.

First, go to the Display menu above the macros in the GMS window. Then choose Convert to CAD. Note: CAD data. is generated from whatever is currently visible in the Graphics window, so make sure that everything you need is displayed before you continue. The new CAD data will appear in the project window as a (*.dwg) file. Now right-click on the CAD data and convert CAD Points to TIN Points. A dialog window will appear asking you to designate which layers of the data you want to include in the conversion and to name the new TIN. You can customize this in whichever way best suits your needs.

This new TIN data can be converted directly into a scatter set. Right-click on the TIN and convert it into a 2D scatter set. 3D scatter sets can be made by simply executing a conversion one more time with the 2D scatter set.

If ultimately you want to compare scatter data with another model, it may be helpful to be able to view both sets of data in the same window. You can easily export the scatter set from GMS by right-clicking on the scatter set in the project window and selecting Export, then open the newly exported file in the GMS window with your other project. The scatter set can also be used to create a boundary for a 2D or 3D Cartesian grid which could be used with an older version of MODFLOW.

Head over to GMS and try converting UGrids into scatter sets today!