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Waypoints over water and Litchi

jmm123

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I know in Litchi you can follow terrain by setting height above GROUND in Waypoints but how does a Waypoint behave above water:
ie: Lakes, sea, and Crystal clear swimming pools?

TIA,

John
 

AZDave

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Waypoints in Litchi and other similar apps use terrain data from Google Earth (Google's Elevation.api) and other sources, so it doesn't make any difference whether your drone is over water, rocks, sand, trees, grass, or marmalade. Whatever those sources think is "ground" at that location is the reference point that Litchi uses.

That terrain data in turn comes from a variety of measurements ... some from satellites, some from various mapping sources, and some from aerial photography. Not all of it is absolutely accurate. For example, the deep and fairly wide ravine that runs across my mountainside lot is not accurately profiled in Google Earth even though the resolution here is as good as I've seen anywhere ... as far as depth goes, the ravine just sort of gets averaged in with the surrounding terrain.
 

Lasidora

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When I pre program the Litchi mission on the PC via Litchi Mission Hub, if any of my flight paths cross uncertain topography such as rapid drops in height or water, I disable the AGL data on that particular set of waypoints so that it flys at the last know height until it gets to what I deem a safe waypoint that has AGL enabled if that makes sense, has worked perfect for when I fly across the River Mersey here in the NW UK, that is where the take off point is over 100ft higher just 0.5 miles inland.
 

Dave Maine

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Note that Litchi is mapped against the actual ground level. It does not know about trees, telephone poles etc. Set your height accordingly.
 

Galopin

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To all your good and important comments on Litchi, I would suggest to pay attention to your drone capability at a certain speed to change altitude from one waypoint to another. If you have to go up a hill or a cliff along your planned flight path, take into account the vertical speed your drone is able to produce according to its horizontal speed in order to reach in time the highest waypoint calculated from the DEM (Digital Elevation Model) of Google Map. You need to settle a progressive change of altitude with several waypoints in order to leave time to your drone to reach the highest point. I made a crash with my Mavic Air to learn it...ah!
 

Lasidora

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To all your good and important comments on Litchi, I would suggest to pay attention to your drone capability at a certain speed to change altitude from one waypoint to another. If you have to go up a hill or a cliff along your planned flight path, take into account the vertical speed your drone is able to produce according to its horizontal speed in order to reach in time the highest waypoint calculated from the DEM (Digital Elevation Model) of Google Map. You need to settle a progressive change of altitude with several waypoints in order to leave time to your drone to reach the highest point. I made a crash with my Mavic Air to learn it...ah!
If flying a waypoint mission that involves steep changes in height I always insert multiple waypoints within close proximity to each other & a curve( in straight line mode) so the height increase is smooth & progressive.