SMS

Discover the Refine UGrid Tools in SMS

The Surface-water Modeling System (SMS) continues to expand its capabilities. Currently, SMS is expanding to make more use of unstructured grids. An unstructured grid (UGrid) is a flexible geometric object that can include cells such as 2D and 3D cells with any number of faces and nodes. This flexibility allows for more realistic modeling of geological features.

In SMS, UGrids can be imported directly or created by converting an existing geometry such as a 2D mesh, 2D scatter set, Quadtree or map feature objects. When creating an UGrid from an existing geometry, it is usually best to make certain the geometry already refined to the level you need for your project. However, sometimes the Ugrid needs to be refined after it has been generated or imported. To do this, SMS provides two tools for refining UGrids: Refine UGrid and Refine UGrid by Error.

Both tools are located in the SMS Toolbox under the Unstructured Grids folder.

The Refine Ugrid uses an existing UGrid then splits (refines) the elements into smaller elements. The Refine UGrid tool provides you with the option to select datasets with “locked” nodes—any node with a non-zero scalar value. Any cell edges that contain one or more locked nodes will not be split. Utilizing such a tool will equip you to complete a surface-water modeling project with focused accuracy and efficiency. .

Example of refining a UGrid

Similar to the Refine UGrid tool, the Refine UGrid by Error tool produces a 2D UGrid that has been refined as a result of an existing 2D UGrid, however this tool integrates elevation rasters into the process. Entering a value that guides the acceptable error threshold, the maximum number of iterations to perform, and the necessary elevation rasters are all required components of the input parameters for this tool.

Being able to refine UGrids adds increased accuracy for your surface-water projects in SMS. Check out the refine UGrid tools in SMS today!

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Eliminate Null Values in SMS

Does your Surface-water Modeling System (SMS) model contain null values? Null values can be useful at times. Some models are even built around them. But what about when you don’t want them in your model? The tools in the Toolbox have ways to change, correct, or exclude data, including null values, without needing to manually edit the files and re-importing them, to clean up the data. These tools have multiple uses for viewing data in different ways, modifying current datasets, and creating new ones from the modifications made.

The Toolbox holds a very useful option in the Filter Dataset. It can be used to modify data in existing datasets by using various filters to include, exclude, or change the data being processed. When you have null values inside your project that you wish to exclude, you can use this tool to eliminate null values and assigning them to 0.

In order to use the Filter option, follow these steps:

  1. Go to Toolbox | Dataset | Filter Dataset.
  2. Click on Run Tool…
  3. Under Input dataset, select the dataset from the dropdown.
  4. For the If condition, select null from the dropdown.
  5. For Assign on true, select Specify from the dropdown.
  6. Enter 0.0 for the Specified Value.
  7. Under Output dataset, enter a new name for the results of the test.
  8. Click OK to run the tool.
Example of the Filter Dataset tool

Once you have created a filtered dataset, the new dataset can then be viewed in the simulation or used with other tools in the toolbox to modify, view, or create other new datasets for better visualization.

This filter function can also be found under Data | Data Set Toolbox… under the Tools section in the left-hand column. It has a slightly different look but the exact same utility.

Head over to SMS and try out the Filter tool to see how it can improve your model results and data visualizations.

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Quick Polygon Generation from Raster Data

Do you have raster data that you like to use to quickly generate polygons for your Surface-water Modeling System (SMS) project? SMS 13.3 introduces the Polygons from Raster Bounds, Polygons from Index Raster, and Polygons from Raster Nodata tools Each of these tools make use of raster data to generate polygons in the Map module. This can help you quickly define model domains or areas of interest in your model.

All of these tools can be found under the Coverages section in the Toolbox. Two of these tools can help resolve issues where the raster data is missing data. These "no data" areas can occur when the raster is trimmed, or when some of the data is incomplete in the database of origin.This can create holes in the data that will interfere with a model.

Polygon from raster data tools in SMS

Using the Polygon from Raster Bounds tool creates a polygon that includes only the active region within the raster. It is especially useful when a downloaded raster has been trimmed to the model area. It eliminates the "no data" areas on the edges that were created by the trimming. This cleans up the data for the model. It can also be used when running models, such as for flooding, when one area needs a different coverage than the original.

With Polygons from Raster Nodata tool, areas that are "no data" inside active regions can be separated from the active regions so the "no data" areas don’t interfere with the model. For example, modeling a river, but not the flood plain, means you may want to exclude the land including islands in the river. Using this tool, polygons can be placed around all active areas and defined for the surface water model while the NODATA areas can then be ignored.

The Polygons from Index Raster tool can come in very handy when elevations and materials match fairly well. It will only work if an index raster is being used. Using this tool, polygons can be created around elevation changes in such a way that it becomes much easier to assign materials to polygons.

Creating the polygons can be a time consuming task. These tools can automate part of the process and eliminate some of the problematic areas within your surface modeling area for you. You can use more than one of these tools, as your model requires.

Head over to SMS and try out these tools in the Toolbox today.

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Accessing 3DEP Data for SMS

The Surface-water Modeling System (SMS)[2] continues to expand the types of data it can use for your water modeling projects. For models in the United States, there is a very comprehensive set of elevation data that you can use in your modeling–3DEP data.

3DEP data is an amalgamation of high-resolution 3D elevation and 3D hydrography data from multiple sources. It is also "bare earth," meaning the images are ground-level only. No buildings, trees, shrubs, or ground cover of any sort have been included. Seeing the most precise shape of the ground can be very important to surface modeling. The high quality lidar data in the 3DEP project covers the vast majority of the United States and several of its territories. Coverage is becoming more comprehensive over time. We have added 3DEP as one of our options when you import map elevation information from the web.

When creating a surface-water model, you are looking for the USGS 3DEP Bare Earth DEM (North America) option from the web.

Example of the 3DEP data

To access 3DEP data in SMS, do the following:

  1. Click File | Import from Web… to open the Virtual Earth Map Location.
  2. Make your location selection here (United States and some territories only)
  3. You may have to set your Display Projection settings
  4. When you reach the Data Service Options dialog box, scroll right until you see an option for USGS 3DEP Bare Earth DEM (North America).
  5. You then save your image to the appropriate location on your computer, after you set or accept the default raster cell size.

Once you have saved your image, it will show up in the Project Explorer window under GIS Data. When saving, it will add the " _elevs.tif" extension to the name you chose. The elevation data can then be applied to your model in the usual way.

Head on over to SMS and see how 3DEP data can help your surface-water modeling.

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