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  1. chruzzie

    Dec 14, 2015
    Likes Received:
    Gold Coast
    Any idea why the camera info on my images is showing a negative reading?
    On my HUD on the iPad it shows 0 when it takes off. But the image info is not correct.

    Attached Files:

  2. Sim597

    Mar 5, 2016
    Likes Received:
    Is that what the logs look like? Where or how did you get to this page? Can you tell me the software you are using?
    Sorry I don't have info, I've seen mine say in the app I'm like -6' or so, but only when it really is lower then take off point, that's like almost 190' that's a lot

    Sent from my iPhone using PhantomPilots mobile app
  3. r62ewa

    Mar 30, 2016
    Likes Received:
    Google an EXIF reader and you will find free ones to download. Then you just use the program to open your image and you can see all of this metadata and even change it.

    The elevation data recorded for our photos are inaccurate with the elevations being recorded as 'Below Sea Level'. It's hard to explain the specifics as I'm trying to figure it all out myself but I've been in contact with Pix4D Support about the negative elevations and they gave me details on how DJI algorithms store the elevation data.

    Here is what Pix4D sent me:

    "In the latest public DJI firmware (FW_V01.05.0030), it seems like DJI changed the georeference of the vertical coordinate.

    They used to provide information above ground level (AGL) using the altimeter of the drone, but by default in the EXIF of the images that DJI writes, they define the datum as "Mean Sea Level". In the latest version they changed this setting to "Below Sea Level", which might be confusing. Apparently, they tried to fix the relative elevation and retrieve the absolute elevation but they probably made a mistake with the reference name.

    There is a DJI forum post related to this issue:
    DJI Forum|Photo,exif Altitude incorrect? Possible Firmware bug?

    The consequences are the following:
    - When Pix4Dmapper reads the geolocation contained in the EXIF, the software is misled and interpret "below" as a negative value. If the EXIF is edited, meaning "below" is replaced with "above", this fixes the problem.

    - The vertical coordinate is still not fully reliable. Indeed, we tested it and even if the previous AGL altitude value is indeed smaller than the MSL altitude value (discarding the minus sign), we noticed a offset in the vertical coordinates.

    Our developers still suspect something wrong in the DJI EXIF regarding the vertical coordinates.

    As a consequence, we always recommend to process with ground control points (GCPs) in order to fix these uncertainties."
  4. Marcus-SEA

    Jul 13, 2016
    Likes Received:
    Hello, I am a newbie, just bought the Phantom 4 about a week ago.

    I am having the same altitude incorrect reading issue. Sometime it showed -190m (yes, negative) eventhough the P4 is way above the ground. I did firmware update, I IMU calibrated twice and compass calibration before the flight.

    The dealer did not provide much help to resolve the issue, so I wrote to DJI support and after they studied my flight data they replied the following:

    "Just be informed for our engineer that this situation is normal, please do not worry.
    It happens because the local barometric pressure is not stable, the barometer on the drone shows the wrong message. You can place the drone on the ground for some time, it will go back to a normal value, sometimes it may be slow."

    The second issue is I noticed the P4 flew much higher than my input to the controller. Normally I flew about 40 to 45 meter (reading from the altitude meter before it went to negative value), then slowly I noticed the P4 flew higher and higher (I left the left stick untouched once reached 40m) and this can be proven from the photos and videos recorded, it definitely higher than my intended 40m. Asked DJI support and pending their reply.

    The third issue - I noticed some part of the recorded videos (4k in the sd) were grainy when I moved the gimbal. This they yet to attend to me.
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