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FW 1.07: EXIF Altitude data in photos changed (again)

Discussion in 'Pro/Adv Discussion' started by PrecisionAeroworks, Mar 24, 2016.

  1. PrecisionAeroworks

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    If you care about such things, be aware:
    With FW 1.07, the EXIF GPS altitude data field is, once again, being populated with the (highly inaccurate) ASL value reported by GPS. This value can be off by 100 meters or more.

    Starting with (I believe) FW 1.05, a change was made and the camera began writing the barometric AGL altitude into this EXIF field. This behavior continued in FW 1.06.

    This was a very good change for those of us that use the P3 for photogrammetry, mapping and 3D modeling. This meant that multiple flights from the same takeoff point could be used together, apples to apples, without having to edit the EXIF info of the many individual images.

    Now, under 1.07, the system has reverted to using the GPS derived ASL altitude. This means that two identical flights from the same takeoff point can have an offset in recorded ASL altitudes of more than 100m.

    Incidentally, the camera also started recording camera orientation angles (Omega, Phi, Kappa) in the EXIF data under 1.07 as well. This is a good change, as this data is used by mapping software such as Pix4dMapper.

    Attached is the image properties table from Pix4d. These images were not synced by the capture app (which can change EXIF data). They are straight off the SD card.

    To illustrate the point, in the attached image, the recorded altitude values are ~1748m. The takeoff altitude was ~1494m, and the mission was flown at 90m. The expected value in that field would be something like 1584m. That's more than 160m off! You can also see the inclusion of the Omega, Kappa, and Phi values.

    TL;DR
    FW 1.07 jacked around with the recorded altitude value in the EXIF data, if you care. image_properties_p4d.jpg
     
    Reed L likes this.
  2. randykahl

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    I've never trusted that number in Lightroom anyway. Saw the word photogrammetry and eyes perked a little... Photogrammetrist here


    Sent from my iPad using PhantomPilots mobile app
     
  3. PrecisionAeroworks

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    ^^The P3 is a truly wonderful measurement tool, when used properly. These undocumented (and inadvertent?) little changes can be quite the headache, though...
     
  4. SamEAS

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    I know this post is a few weeks old but how are you guys accessing the barometric data from the EXIF now? I have tried several different EXIF viewers but can only see the "GPS" altitude.