Power lines are difficult to scan because they are relatively high, small, linear, and long. None of these factors are ideal for Hovermap, but following this process produces consistent scans of power lines, towers, and the surrounding vegetation.
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The recommended process is as follows.
What you will need
A drone with Hovermap mounted.
Emesent Commander installed on the tablet, with a working connection to Hovermap.
Aura installed for processing the scan data after capture.
Familiarity with Pilot Assist mode and the Shield feature.
A safe and controlled take-off and landing area near the first tower in the corridor.
Procedure
Step 1: Analyse the environment
Analyse the terrain before starting the scan. This is particularly important when scanning power lines, as the power lines themselves are not a suitable feature, and Hovermap needs to retain visibility of features on the ground.
Consider the following when planning the mission:
The recommended flight height is no more than 40 m. Follow the terrain as much as possible to stay consistently at this height.
If the power lines span a valley deeper than 100 m, Hovermap cannot be used, as its absolute range is 100 m.
Heavily vegetated areas can pose problems, especially on windy days. Hovermap relies on the environment being relatively static. If a tree or branch is moving, the scan data may become inaccurate.
For long stretches, break the scan into approximately 500 m increments with around 100 m overlap between segments.
Hovermap's absolute LiDAR range is 100 m. If the power lines span a valley deeper than 100 m, the scan cannot be completed and an alternative method is required.
Step 2: Complete pre-mission checks
Complete the required pre-mission checks.
Step 3: Perform the mission
Take off next to the first tower in Pilot Assist mode. Face the tower during take-off, as it is an important feature in the scan.
Enable Shield, then test it by trying to land the drone. Shield prevents the drone from landing.
While scanning, check the live point cloud in Emesent Commander to ensure data is being collected correctly.
Scan the tower by spiralling upward around it. Continue to face the tower at all times during this manoeuvre.
Fly the drone down to below the height of the power lines. Keep to a flight height of 40 m as much as possible. Hovermap needs to retain visibility of the ground.
In Pilot Assist mode, fly in a zig-zag pattern underneath the power lines. The zig-zag pattern captures more of Hovermap's surroundings, allowing for a more accurate scan.
When the drone reaches the other end, spiral upward around the tower as in step 4.
Bring Hovermap back down to below the height of the power lines.
Return to the original tower, flying back in a zig-zag pattern and keeping to a height of 40 m.
Perform one final lap around the original tower. This final lap only needs to be a single circle around the tower (facing the tower at all times), which helps Hovermap understand where it is. The tower does not need to be captured again.
Land the drone.
Step 4: Process the scan data
Process the scan data in Aura. Select the Standard profile for the first job.
If the results are not as desired, change the processing parameters. For a linear scan such as power lines, the recommended changes to the Local Mapping parameters are:
Section | Parameter | Value |
|---|---|---|
Local Mapping | Sliding size in seconds | 15 |
Sliding shift in seconds | 0.6 |
These parameters work more often than not, but results still depend on the specific environment. If the result is not as expected, adjust the remaining settings. Be aware that tuning beyond the recommended parameters significantly increases processing times.
Outcome
The power lines, towers, and surrounding vegetation have been scanned and the scan data has been processed in Aura.
Related documentation and support
For assistance, contact the regional Emesent partner or the Emesent Client Support team.