Maps Made Easy Drones Made Easy

Ground Reference Images

Tudor -

Since DJI aircraft populate the image geotags with using the barometric altimeter (relative to the home point) and not the GPS altitude (absolute above sea level), Map Pilot automatically records an image at the takeoff point after the start of every mapping flight.

Include this image in your upload to Maps Made Easy for proper elevation offset calculation and elevation readings.

 

NOTE: Due to how Maps Made Easy uses ground reference images to correct for the use of the barometric altimeter in its elevation processing, it is highly recommended to take off from an area of undisturbed ground. Taking off from man-made structures or in areas of heavily modified earth will not correspond well to the reference values we get from the NASA SRTM elevation data and will result in elevation offsets.

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Comments

  • Avatar
    flitelab

    Do you include this image in the selection with all the main images or separately when it prompts on the EXIF file request? Wasn't clear when and where I should include the file from the ground, included it as part of the full set.

  • Avatar
    Tudor

    The ground reference image (image taken when the aircraft lands) should be uploaded along with all of the other images.

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    Jos Bol
    Instead of taking the reference image when landing, could it (also) be taken at take off? We don't let our phantom land on the ground, but on our hands above our head. We end up with a cool picture of us looking up at the drone, but I doubt it's of any use :) .
  • Avatar
    TwoRivers

    Tudor - Can you please explain how not including these ground reference images will affaect the end product? What exactly will be adversely affected? I have created several maps where I exlcuded these images thinking they may be detrimental, not useful.

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  • Avatar
    Doug Thost

    I recently flew a survey south of 60*S (in Antarctica) using Map Pilot, and processed on MME. The DEM is pretty close to what I expected to get, but I'm just wondering where the reference image sourced an elevation AMSL for calculations from. The shuttle data doesn't extend that far south. Did it just "get lucky" or is there another data set it can access? Airbus WorldDEM (he asked, hopefully)?

  • Avatar
    Tudor

    Sorry for the delay.
    It is embarrassing but we actually use the MapQuest elevation API for the ground reference image offset.

    https://developer.mapquest.com/documentation/open/elevation-api/elevation-profile/get/

    It has good coverage and good terms. We have no idea where they get their data for down there though.

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