SMS

2D Mesh Editing Versus Regeneration: Which is More Apt?

By aquaveo on August 6, 2024

If you need to make a change to a mesh, should you use the toold in the 2D Mesh module to edit, or instead regenerate the mesh? A 2D mesh consists of elements that define the computational domain of the numerical model. A numerical simulation requires a geometric definition of its domain– the mesh, available for use in SMS 13.3. Occasionally when constructing a mesh, a moment occurs where the mesh is insufficient for any reason.

In most cases the recommendation is to regenerate the mesh; as opposed to editing the mesh manually. The following list involves common circumstances where one may manually edit a mesh:

There is no mesh generator coverage present.
Deleting Outer Elements: Since the triangulation process creates elements (i.e. thin triangles) outside the mesh boundaries, deleting outer elements provides some refinement.
Merging Triangles/Element: Numeric solvers are more stable and accurate when quadrilateral elements are rectangular and triangular elements are equilateral.
Editing Individual Elements: After compound edits, a mesh could benefit from individual manipulation to increase stability. Swapping edges: Think of the two triangles as a quadrilateral, and the common edge between them is a diagonal of the quadrilateral. By swapping this common edge, it changes to be along the opposite diagonal of the quadrilateral. If this edge is clicked again, it returns back to its original state.
Turning a specific element into a void element.

You may make edits in the Mesh Generator coverage. Manual edits should be intentional and reserved for small sections of a mesh. Generally, manual edits of a mesh ought to be minimal.

In nearly all cases the recommendation is to regenerate the mesh; as opposed to editing the mesh manually. This is because any process that edits a mesh, causes the node and element ordering to become disorganized. Additionally, editing a mesh invalidates any solution files that have been previously saved. Manually editing a 2D mesh risks creating issues with the assigned elevation data or other datasets being used. As such, if there is a solution dataset attached to the mesh, the model simulation should be re-run.

A useful tip is reviewing your mesh before generating, using the preview tools that are available in a given dialog. Make adjustments to the arcs, vertices, and polygons on the mesh. Do not be afraid to add more arcs, vertices, or polygons if further refinement is needed.

If you want to generate a new mesh with the desired edits, you will need to create a mesh generator coverage. The following are examples of tools that can create a new mesh:

Map → 2D Mesh tool.
2D Mesh from 2D Grid in the toolbox.
Additionally, most of the Unstructured Grid tools may be utilized to generate a new mesh.

Make use of the mesh editing and generating capabilities of SMS 13.3 today!

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SMS

Discover the Refine UGrid Tools in SMS

By aquaveo on July 23, 2024

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. .

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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SMS

Eliminate Null Values in SMS

By aquaveo on July 16, 2024

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:

Go to Toolbox | Dataset | Filter Dataset.
Click on Run Tool…
Under Input dataset, select the dataset from the dropdown.
For the If condition, select null from the dropdown.
For Assign on true, select Specify from the dropdown.
Enter 0.0 for the Specified Value.
Under Output dataset, enter a new name for the results of the test.
Click OK to run the 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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SMS

Quick Polygon Generation from Raster Data

By aquaveo on June 25, 2024

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.

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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