Spotting Vertical Obstructions in a point cloud
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:
- Use the blue/red height color palette rather than earth tones. This makes individual points “pop” visually.
- 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.
- Increase lighting brightness.
- Make points larger in the “set point size” tool.
- Tilt the model on its side so you can scan “across” it.
- 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”.
- 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.