Spotting Vertical Obstructions in a point cloud

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Vertical Obstructions (VO’s) are hazards to aircraft approach. They are best seen in a point cloud, not a DEM. Here a few tips to search for them manually in a point cloud:

  1. Use the blue/red height color palette rather than earth tones. This makes individual points “pop” visually.
  2. Turn off intensity/vertex colors. While intensity is useful in most cases, it just moderates the point color when performing a visual scan, thus minimizing the brightness of individual points.
  3. Increase lighting brightness.
  4. Make points larger in the “set point size” tool.
  5. Tilt the model on its side so you can scan “across” it.
  6. Keep the point cloud moving – your eye will spot things better if the point cloud is in motion – even if just a little “back and forth”.
  7. If you have LAS files with multiple returns, use the QTA Quick Color button to color by “First/Last/Intermediate”. Vegetation and Power lines will be obvious.

It may be helpful to document towers with a marker. Hold down “SHIFT” to interrogate individual points, then click “Create Marker” to drop a marker onto the VO. Markers can be exported as SHP, KML, or ASCII text files, or sent downstream to other QT Modeler/QT Reader users as a native QTM format.

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