Tuesday, May 13, 2008

Setting the Elevation of Contours using Edit Geometry

One of the common tasks in the terrain modeling workflow is to interactively tag vector contour lines with an elevation. I could not find a command in GeoMedia Terrain 6.0 or any steps in the delivered documentation. I could do the job with GeoMedia's Functional Attributes but I have to calculate the elevation values manually taking into account the storage units and my height unit preference - that would definitely scare users away. I later found out that I could also use GeoMedia Professional's Edit Geometry command. Here are the steps to tag contour lines with elevation with the Edit Geometry command.
  1. Activate the Selection Tool.
  2. Select a contour line geometry in the map window.


  3. In the GeoMedia Professional Edit pulldown menu, select Edit > Geometry > Edit.

    All the vertices in the contour line are displayed as black handles.


  4. Click on a vertex handle on the contour line to select it.

    The selected vertex is displayed as a purple filled circle.


  5. Right click in the map window to bring up the Edit Geometry context menu.


  6. Choose Select All.

    All the vertices are selected and are displayed with purple filled circles.

  7. Right click again in the map window to bring up the Edit Geometry context menu again.
  8. This time, choose Edit Height.

    The Edit Height dialog appears.

  9. In the Edit Height dialog, type in the height value.
  10. Click OK.

    The height of the contour line is changed to the new value.

  11. Press ESC.

    The Edit Geometry command is deactivated.
The good points about Edit Geometry are that the height units follow the user's preferences set and the height changes can be undone. On the downside, the workflow is still a little cumbersome having to select all the vertices (which take a while if a contour line has a lot of vertices). I just might decide to write a GeoMedia custom command just to set the elevation of geometries.

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