These are the recommended processing settings for GCP, found in the GCP tab of Processing Settings in Aura. Adjust them when the default profiles are not detecting or matching targets as expected. For the full procedure, see Processing scan data with Ground Control Points (GCPs).
The settings below primarily affect how compatible targets are matched automatically. Target position uncertainty can also affect the accuracy of the processed, georeferenced point cloud.
Option | Description | Use case |
|---|---|---|
Intensity | The expected range of intensity values of the retro-reflective targets. ST-X: 250 to 255. ST/HVM100: 150 to 255. | Use when automatic match targets are not being detected as expected. Narrow or widen the range until reflective targets appear within the detection band. Adjust the band based on the reflectivity of the targets. Widening the band allows Aura to identify more targets but may also pick up additional reflective objects such as bollards, signs, or vehicle mirrors. |
Number of points | The minimum number of points required to detect a target. | Use when auto-detection of targets is inconsistent. Increase the value when false positives are being created in dense scans, as requiring more points reduces the chance of random clutter being flagged as a target. Decrease the value when targets are small or only partially scanned, so Aura can still identify them with fewer points. Increasing the value will cause sparsely scanned targets to be missed, while decreasing the value will increase the number of false positives. The default value is 25. |
Point cloud target noise | The expected noise or thickness of the LiDAR points on the target. | Use when targets appear noisy or when clusters of points around a target are unusually thick. Increase the value if targets are not being detected due to excessive noise or if reflective surfaces appear fuzzy in the scan. Decreasing the value makes detection stricter, which can prevent misidentifying clutter as targets. The default value is 0.02 m (20 mm). |
Target position uncertainty | The uncertainty in the position of the surveyed targets. | Use when SLAM alignment appears over-constrained to the control points or when survey accuracy is uncertain. Increase the value to give Aura more flexibility when fitting the point cloud to survey data (for example, if control points have lower confidence or if overfitting causes distortions in the cloud). Decrease the value when survey control points are highly accurate and should strongly constrain the SLAM alignment. The default value is 0.003 m (3 mm). |