Contour Following

Michael Porritt

Hi Everyone,

Im planning missions in some mountainous areas and plan to have the drone fly at 60m above takeoff point, following the contours of the area. My question is this - when the drone finishes the mapping mission, if it is for example at -50m from the initial takeoff point, will it go up to the normal +30m as set in the DJI settings then return home? Similarly, if the drone finishes the mission at +120m from its original take off point due to hills, will it drop to +30m to come home and potentially crash into the hill?

Not sure if the software constantly adjusts the perceived RTH altitude based on the contours it has been following. When I go to the mission planner it has the drone flying into the mountain when it goes from one mapping component to the other, so do I need to put waypoints in there with actual heights to ensure the drone doesn't crash?

Havent had much experience with the contour following mapping missions, so any advice would be great.

Cheers,

Michael.

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Comments

11 comments

  • Comment author
    Martin Reading Dronelink Expert Dronelink Expert

    Hi Michael Porritt, for Terrain follow with mapping which is what I assume you are talking about you need the professional starter plan, details here https://app.dronelink.com/pricing/professional

    With regards to your other question regarding  RTH height, yes if its below the return to home height it will rise to the return to home height and then fly home, if above the return to home height it will just fly straight home, the thing to remember about RTH height is its the minimum height the drone needs to be before heading home

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  • Comment author
    Barry Houldsworth Dronelink Expert Dronelink Expert

    I think the question on RTH is whether RTH is based on the start location or the final location.

    I'm 95% sure that RTH is based on the start location. 

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  • Comment author
    Mike (Arizona Wyldwest) Dronelink Expert Dronelink Expert
    • Edited

    Actually Barry is 100% correct. lol. RTH altitude is always based on the take off location. The drone functions the same as with DJI app due to all those functions a being stored on the drone and It will never lower in altitude as Martin stated. Most important thing to do is to set the RTH altitude well above any object or structure and as always be ready to take control if needed and ascend manually. Then you can either fly back or hit RTH and it will return at the altitude you ascended to. Here is a link on how to take manual control and depending on which drone/ controller you have there are two or three ways. Very important. Also if you can share your plan someone can look at it and maybe find out why it’s flying into the terrain while moving to to another map.

    https://support.dronelink.com/hc/en-us/articles/360036830214-How-do-I-take-over-control-during-a-mission-

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  • Comment author
    Michael Porritt

    Thanks guys - its the Mavic 3 Enterprise Thermal.

    The issue I saw with the drone flying through the terrain was when the start location was the furthest point in the map and the drone was flying transects back towards the take off point. There was a ridge in between the take off location and the start of the map was at -50m. As the drone was flying to the start of the map at 60m altitude, it calculated that height as -50m + 60m = 10m altitude... So theoretically once the map starts it will terrain follow, however getting to the start point of the map from its takeoff point it will not...

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  • Comment author
    Michael Porritt

    Oh - one other question.

    The map plan shows 2 elevations, one at the beginning of the map and one at the end. I assumed that these were the actual altitudes that the drone would be at due to terrain following compared to its take off location. However looking at the map the elevations seem to be reversed. The attached shows the map in question, the start point is actually 113m above take off location, and the finish is 60m, however the map shows these figures reversed.... Any ideas why?

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  • Comment author
    Martin Reading Dronelink Expert Dronelink Expert

    can you share the mission so we can look at in 3D

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  • Comment author
    Michael Porritt

    https://app.dronelink.com/michael-porritt-y9lQ7XeKYhXHpjULZcVg/public/plan/rBOiOONoDIUZyXNAMB7s/JdQs4u4fa2ApHe7HkAh4

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  • Comment author
    Barry Houldsworth Dronelink Expert Dronelink Expert

    So I think the concern is that the drone won't climb high enough initially for the flight to the start point.

    A few suggestions. 

    First, if you run a simulation you can scroll down and see the altitude graph and that might given you some confidence. 

    And if you run it in 3D in Google Earth, the path seems to avoid the trees, you can see that below.

    But, ultimately, if you are really concerned then the best option is to manually launch and fly near the start point and then hit play.

    Best of luck with the flight!

     

     

     

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  • Comment author
    Mike (Arizona Wyldwest) Dronelink Expert Dronelink Expert

    The map start is the blue waypoint at 60m which is the altitude you set it to. The red dot is the end. Looks correct.

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  • Comment author
    Michael Porritt

    Thanks guys, the plan I was initially talking about wasn't posted, the client wanted a different area so that plan was changed. The question was more to do with the 2 altitude readings on the plan - 60m at the start of the flight and 113m at the end.... What are these representing? The beginning of the plan is the height where it should be 113m and the end should be 60m so it seems these are reversed.

    Its not just this plan either, all the plans I have made with terrain following have a similar weird altitude readings at the start and finish of the plan.

    The original question has been answered - travelling to or from a terrain following plan, the drone won't follow the contours, so we either have to manually fly these parts or use waypoints as a work around.

    Cheers,

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  • Comment author
    Mike (Arizona Wyldwest) Dronelink Expert Dronelink Expert
    • Edited

    I understand what you’re asking. The Map is running at the 60m you set relative to the ground at start and will keep that altitude. If you click on the 3D view at the top of the mission card you can rotate it and see the path is following the terrain based on that 60m. The end of the map is just showing relative to the takeoff location which is obviously different. Maybe this link will help to explain it.

    https://support.dronelink.com/hc/en-us/community/posts/18397555006483-Final-mapping-altitude-when-AGL-is-set-

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