The 3D model of cell towers that were not captured using ground control points (GCPs) may occasionally lean:
A slight lean is usually caused by a lack of accuracy due to the absence of GCPs and can be considered normal. For example, depending on its height, the top of a tower might be shifted by up to one to two meters relative to its base. For more information about the accuracy of SiteSee 3D models, please consult this page.
A more pronounced lean can be caused by several factors (or a combination thereof):
- A low-quality site overview orbit: Make sure that the site overview orbit is well centred on the tower and all images capture the tower fully from base to top. Avoid capturing in strong, gusty winds.
- GPS interference (e.g. from the antenna panels) during the capture. In these situations, we strongly recommend the use of GCPs.
- Inaccurate GPS on takeoff: This can become an issue particularly in environments that make it difficult for the drone to obtain a GPS lock (e.g. where there is GPS interference from the tower or where there are many trees, etc.). It is recommended that, after the GPS icon in the app turns white, pilots wait another minute before taking off.
- Camera gimbal roll miscalibration: If the gimbal roll is misaligned, all images captured will show a slight but consistent rotation either clockwise or counterclockwise. If the gimbal roll is off clockwise, the images will show a counterclockwise rotation and vice versa. It is often possible to see this roll when looking at the horizon in the RAD scan images:
In this case, the gimbal needs to be calibrated. Consult your drone's user manual for instructions on how to do so.