I am interested in trying an SF10 Rangefinder from Lightwave, to fly with terrain following. What I am not clear about is how the Terrain Following function works when interacting with a MP WP mission using:
Select ‘Terrain’ altitude selection for the WP mission
Operating remotely in the field with no Internet access, to download new map SRTM data
The SF10 rangefinder
Docs say: "The database is populated automatically by the autopilot requesting terrain data from the ground station over a MAVLink telemetry link. "
Is this required if I use the SF10 to determine height above the ground? If I use the SF10 rangefinder to fly at a specified altitude above the ground, does MP need to send SRTM data via telementry to my copter?
So how does Mission Planner know it does NOT have to gather and transmit SRTM data during a mission via telemetry? Are the Rangefinder settings somehow making this magic happen?
SERIAL4_PROTOCOL = 9 (Lidar)
SERIAL4_BAUD = 19 (19200 baud)
RNGFND_TYPE = 8 (LightWareSerial)
RNGFND_SCALING = 1
RNGFND_MIN_CM = 5
RNGFND_MAX_CM = 2500 (for SF10A), 5000 (for SF10B), 10000 (for SF10C) or 12000 (for SF11C). This is the distance in centimeters that the rangefinder can reliably read. The value depends on the model of the lidar.
RNGFND_GNDCLEAR = 10
Mission Planner is asked for the SRTM data, so if it isn’t asked for it, it shouldn’t send anything. I’m not 100% sure that ArduPilot doesn’t ask for it when using a rangefinder though, but it should have zero impact on the way it operates if you have the rangefinder.