Computing volumes with SMS
Required
- Geometry – 2D mesh, UGrid, or scatter set.
- Delta dataset on the geometry of the spatially varied elevation.
- This can be computed in the dataset toolbox
- Examples include:
- Delta bed dataset computed by a sediment transport model
- Delta water surface elevation computed from two different water surface values
- Polygon of region to be evaluated
- Can be defined interactively but recommendation is to define it in a map coverage
Setup steps
1. Load data files.
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1. Gather and open image files.
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Images are imported into the GIS module in SMS.
2. Import images from the web.
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2. Select the desired "delta" dataset
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- The delta dataset with the elevation values needs to be active to calculate volumes. The dataset can be on of the following:
- 2D Mesh
- 2D Scatter set
- UGrid
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3. Load or define the polygon for the delta volume area.
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- A polygon on an map coverage is needed to compute volumes.
1. Use an existing map coverage or create a new map coverage.
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2. Import a polygon for the delta volume.
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- Use the File | Open menu command to open a file containing a polygon.
- Depending on the file type, the polygon may need to be converted to a map coverage.
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3. Define the polygon for the delta volume.
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1. Create enclosed arcs for polygon area.
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1. Create feature arcs, nodes and vertices.
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- In the Map module, create feature objects in the active coverage.
- Use the Create Feature Arc tool to create arcs in the map coverage.
- Begin creating a new arc by clicking in the Graphics Window at either arc end. If clicking on an existing feature node, vertex or arc, the new arc will snap to that object.
- Double-click or press the Enter key to terminate the arc.
- Use the Create Feature Node tool to create additional nodes alone or to split arcs.
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2. Modify arcs.
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- Feature arcs often need to be edited after initial creation.
3. Split arcs.
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- An existing arc can be split by:
2. Add a node the arc.
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- Use the Create Feature Node tool to add a node on an arc in order to split it into two arcs.
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3. Add a new connecting arc.
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- Use the Create Feature Arc tool to start or end a new arc on an existing arc to split the existing arc into two arcs.
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4. Merge arcs.
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- Two arcs that share an end node can be merged together.
- Select the shared node using the Select Feature Node tool.
- Right-click on the node and select the Convert to Vertex command to merge the arcs.
- If desired, the Select Feature Vertex tool can be used to select and delete the new vertex.
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4. Make certain the Volume option is on.
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- Select the File | Info option... menu command.
- In the Selection Information dialog, make certain Volume is turned on.
- If desired, unselect quantities that are not of interest.
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5. Compute volume in the Select/Delete Data dialog.
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- Select the polygon (or polygons) that cover the region you want to compute the volume for
- Use Select/Delete Data... command in the Feature Objects menu.
- Compute volume in the Select/Delete Data dialog.
- Leave the Data Domain setting as "Inside polygon(s)"
- Select the geometry in the tree on the lower right side then select
- "Elements" if the geometry is a mesh
- "Triangles" if the geometry is a scatter set
- "Cells" if the geometry is a UGrid
- SMS will switch the module to the geometry module and select the elements, cells, or triangles inside the polygon(s)
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Results
The volume will be reported at the bottom of the graphics window in the status bar.
The other info options allow for this to be saved to a file or displayed in a separate window.