Differences in Radar and Lidar rangefinder types:
The Methane detector is now configured to work with a Radar rangefinder, Lidar rangefinder, and for terrain follow without a rangefinder in missions. Users may choose which rangefinder they're using from a dropdown in WGC.
Surface tracking in auto works comparably between the two sensors, with the Lidar being more responsive to smaller changes.
Surface tracking in Loiter for the Radar looks comparable to its performance in Auto, whereas for the Lidar we see filtering of large, flat objects or structures that the sensor more or less equates with "ground".
Performance for both sensors should be suitable for hilly/sloped terrain when flying in manual. Radar will be more reactive to sharp elevation shifts, such as flying over a roof.
Difference between Terrain Follow with rangefinder vs no rangefinder:
Terrain Follow without a rangefinder uses global terrain data to direct the elevation adjustments of the drone based on the information it receives from the terrain tiles that are downloaded. A conversion occurs based on local position in relation to the reference point, which takes into account the Earth’s curvature during this process.
As a result of this process, this form of terrain follow is only considering the geography of the terrain on a larger scale, and often may not include structures that are present, though this isn’t always the case.
Terrain follow with a rangefinder is actually known as surface tracking. As the name implies, it functions based on the active readings that the rangefinder gets from the ground and classifies it a local Terrain data, which then sends corrections to the GPS to adjust height based on the object detected.