Friday, May 23, 2008

Validating Geometries with Z Values

GeoMedia Fusion 6.0 has a useful command - Advanced Validate Geometry to validate and correct 3-D geometries like contour lines, drain lines, lakes etc. before loading into GeoMedia Terrain geomorphic datastores. The command can detect the following anomaly types with regards to the Z values:
  • Area not closed in Z-plane
  • Z out of range
  • Not monotonic
  • Not flat
  • Z breaks
Area not closed in Z-plane Anomaly Check
This anomaly check is great for validating polygons to ensure that the first and last points are vertically closed i.e. have the same Z value.

Z Out of Range Anomaly Check
The Z out of range check will ensure that the geometries fall within a specified minimum and maximum range.

Not Monotonic Anomaly Check
Useful for validating geometries representing drainage lines; this will verify that the geometries have uniformly increasing or decreasing Z coordinates.

Not Flat Anomaly Check
Good for validating flat geometries such as lake polygons, contour lines.

Z Spike Anomaly Check
This check will look for spikes or abrupt changes in the Z coordinates of geometries.

Z Break Anomaly Check
A Z break refers to consecutive points of a geometry on the same XY position but with different Z coordinate.

Using the Advanced Validate Geometry Command

  1. From the GeoMedia Professional pulldown menu, select Fusion > Advanced Geometric Validation > Validate Geometry.

    The Advanced Validate Geometry dialog box appears.

  2. In the Input tab, toggle on the features you want to validate.
  3. Click the Anomalies tab.
  4. Expand the Anomaly Types node and toggle on the Z (height) checks you want to validate for.

  5. Select a Z (Height) anomaly type check e.g. Z Out of Range and define the Anomaly Properties e.g. Minimum Z. For some anomaly types, there would be an option to auto-fix the anomaly.

  6. Click the Output tab.

  7. Type in the name of the queue and/or the name of the query.
  8. Click OK to start the validation process.
  9. You can use the Queued Edit command to review the validation results and correct the geometries using GeoMedia Professional's commands if necessary.

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