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DEM Editing Tool

DEM Editing Tool

When you click Load DEM Result to Display with Band Edit in the last step of the DEM Extraction Wizard, the DEM Editing Tool dialog displays and the DEM is loaded into a display group. The DEM Editing Tool enables you to interactively edit pixel values within a region of interest (ROI) using one of seven different methods.

You can also access the DEM Editing Tool by selecting Terrain > DEM Extraction > Edit DEM Result from the Toolbox.

Note: The edits you make using the DEM Editing Tool are applied immediately to the file. It is recommended that you save a copy of your file to either disk or memory and perform your edits on the copy. This way, the original data file remains intact for additional processing at a later date.

Post-processed DEMs often require editing to remove artifacts, such as setting bodies of water to a constant elevation. There are seven methods available for editing the values of selected posts once an ROI has been defined.

Method

Description

Replace with value

Replaces the ROI with an assigned value. The allowed values depend on the minimum and maximum for the input DEM. You must supply a Value input.

Replace with mean

The mean is calculated for selected posts, and all posts in the ROI are set to that mean value.

Smooth

Low-pass convolution is performed based on the specified kernel size. Larger kernel sizes result in more smoothing. Selected posts in the ROI are modified as a result of the smoothing. The default kernel size is 3.

Median Filter

Selected posts in the ROI are replaced with the median value from the neighborhood specified by the kernel size. The default kernel size is 3.

Noise Removal

If the ROI post value is greater than two standard deviations of the mean of the surrounding posts, it is replaced with the median of the surrounding posts.

Triangulate

Border posts surrounding the ROI are interpolated across the ROI using triangulation.

Thin Plate Spline

Border posts surrounding the ROI are interpolated across the ROI using a thin plate spline method.

Edit the DEM Band


To edit a DEM, do the following:

  1. Select which window to use to define the ROI: Image (default), Scroll, Zoom, or Off.
  2. Select the type of ROI using the Type drop-down list: Polygon (default), Rectangle, or Ellipse.
  3. Select a Color to use for highlighting the ROI. You can change the color by clicking on the color swatch with the left mouse button, or by right-clicking on the color swatch and choosing a color from the color lists. The default is red.
  4. Select the editing Method to use from the drop-down list: Replace with value (default), Replace with mean, Smooth, Median Filter, Noise Removal, Triangulate, or Thin Plate Spline.
    • If you accept the default method Replace with value, select a Value to assign to the ROI. The allowed values are determined by the input DEM data type, maximum, and minimum. There is no default value.
    • If you select the Smooth method, choose a Kernel Size to use for the smoothing kernel. Larger values for the kernel size result in more smoothing. The default is 3.
    • If you select the Median Filter method, choose a Kernel Size to use for the Median Filter kernel. Pixels in the ROI are replaced with the median value from the neighborhood specified by the kernel size. The default is 3.
  5. Click and drag the left mouse button to draw the ROI in the image. Click the right mouse button to commit the selected ROI, or click the Apply to Region of Interest button.
  6. Note: When you commit the ROI by clicking the right mouse button, the pixels are automatically modified according to the selected method.

    The Smooth method can be applied to an ROI or to the entire DEM. To apply Smooth to an ROI, either right-click on the ROI or click Apply to Region of Interest. To apply Smooth to the entire DEM, click Apply to Entire Band.

    The Median Filter method can be applied to an ROI or to the entire DEM. To apply Median Filter to an ROI, either right-click on the ROI or click Apply to Region of Interest. To apply Median Filter to the entire DEM, click Apply to Entire Band.

  7. To delete a selected ROI, click the middle mouse button.

Perform a DEM Edit Undo


A running tally of the edits made to the DEM is shown next to the Edits field in the dialog. All of the edits made can be undone until you click Save Changes. You can made additional edits after you save changes, and you can undo these changes until you save them.

  • Use Undo Last Edit to undo the most recent change made to the DEM. You can repeatedly click this button to undo all of your changes, one by one.
  • Use Undo All Edits to undo all edits made to the DEM since the last Save Changes.

Close the DEM Editing Tool


Click the Cancel button to close the DEM Editing Tool dialog. If you have not saved your edits, a dialog will prompt you to do so. When you exit the DEM Editing Tool dialog, both the DEM Editing Tool dialog and the associated display group are closed.



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