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Thread: REQUEST TO DJI: Photogrammetric GPS and IMU data

  1. #11
    Steve (saabguy from RCG)
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    That logged data will be very inaccurate.

    Yes you can solve the camera position faster but that is about it. Final DEM model creation MUST make use of proper and accurate ground control points. So if you want an accurate model that can be proven to your client you better go buy 20-30,000$ in survery equipment and learn how to use it... as me how I know

    You can make a model with camera position data but nobody in their right mind will pay you for it if you can't actually prove the data and show them the residual error.

    It is a "nice to have" but the last thing I want is this thing hanging up becuase it's logging a GPS position that is at best within 3-5m accuaracy. Typically my GCP's are surveyed to within less than 1.0cm accuracy (or better) and the more accurate your GCPs are the more accurate your model is...

    I don't typically log data onboard any of my aircraft

    If you are looking at selling the data you are aquiring in an accurate manner this is the wrong way to go about doing it. Yes it's cheaper than buying survey equipment and learning how to use it... but proven data is worth money, unproven data is just "cool"

    Steve
    Last edited by uavservices; 12-08-2012 at 07:23 PM.
    Steve
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    Fly safe!

  2. #12
    Steve (saabguy from RCG)
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    if you really want the gps position of each photo you can buy a gps logger, sync it with your cameras time, then you can update the exif file of your photos by syncing them with the logged gps data. This solution does not put any more "strain" on the WKM brain and can also be applied to other systems of your liking...

    I have this http://blip.com.au/item.aspx?itemid=62 and it works well.... I have not used it in ages but as I recall it can log fairly quickly and it may even come with a syncing utility. As you can see accuaracy is 5.0m, even if it was WAAS enabled It may get down to 3.0m


    Steve
    Last edited by uavservices; 12-08-2012 at 07:34 PM.
    Steve
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    Fly safe!

  3. #13
    Full Blown Hucker
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    Lol.

  4. #14
    Approaching Solo
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    I'm new to the Wookong-M Waypoint game but have had a $189 APM 2 for many months. I just assumed the Wookong-M could do the same thing.. like export kml files and show me the height, speed, orientation, and voltage along any point along the way. This really does suck.. I really learned a lot from those logs.
    The Wookong-M is still ahead of the APM 2 on stability.. but the gap is closing.

  5. #15
    Full Blown Hucker
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    Quote Originally Posted by kerbob View Post
    I'm new to the Wookong-M Waypoint game but have had a $189 APM 2 for many months. I just assumed the Wookong-M could do the same thing.. like export kml files and show me the height, speed, orientation, and voltage along any point along the way. This really does suck.. I really learned a lot from those logs.
    The Wookong-M is still ahead of the APM 2 on stability.. but the gap is closing.
    I'd have to say stability is about on par now. I also have a APM 2.0 and a few 2.5 boards. Combine that with the RDF 900 radio model with 40Km range and you have a killer combination. I'm going to be doing more comaprisons with my wookong APM's in the next couple of weeks. My S800 may have a AMP soon lol.

  6. #16
    Steve (saabguy from RCG)
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    very interesting guys, I have up on Ardu anything years ago because it was very unreliable.... interesting to hear it has come a long way.... One day I may have to try it again.

    Thanks for the info and opinions on the APM

    Steve
    Steve
    www.uavservices.com
    Fly safe!

  7. #17
    Defies Physics!
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    DJI do log the data using their Aceone products. Unfortunately they don't allow the .dat files to be read by users rather will view the flight logs when there are problems to help sort them. Apparently the Aceone single waypoint logs are fairly basic while the multiwaypoint uses a completely different box and has more logging going on. I do agree with other that this IMU data should be readable and it certainly wouldn't be difficult to write a small program to allow access to some of the data and hide what DJI don't want us to see. My understanding is that the wookong IMU data isn't accessible and while the iOSD might allow simple things like GPS location and altitude the true IMU that you are after is unlikely to come through the iOSD.

    Steve - is right a simple external GPS connected to the camera can be utilised by cameras and then the some of the programs such Pix4d can read the exif header but i disagree that the data from these programs are not useful. Yes they may need some additional accurate 1-2cm GCP's to help rectify the image but some of the models being produced from these techniques and from others based around structure from motion are on par with DEM's produced by lower grade Lidar and particularly useful in modelling canopies and other structures.

    That said i suspect the IMU data flowing from all DJI products will contain fairly high errors, due to low grade MEMS sensors and because normal GPS is used rather than RTK or other 1-2cm highly accurate data be fairly useless for real reconstruction using traditional IMU based techniques. Also don't forget there are more complexities if you are using a gimbal rather than fixing the camera directly to the frame where the IMU is measuring.

    All that said i wouldn't mind seeing and accessing the IMU data to get an idea of stability of different setups rather than looking at them and thinking they are more stable than others.

  8. #18
    Approaching Solo
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    is anyone familiar with the GS photometry servo setting to trigger the camera? we are using sony nex 7. i can take a picture by clicking trigger and reference photo but it will not take photos automatically in flight. i can click reference photo while we are in flight to take pics but really need it to take pics at the planned times.

  9. #19
    Full Blown Hucker
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    Set your servo for 900, -900 and a short delay. But you'll need to use the photogrammetry function, not the scan to trigger the camera. just before you upload you should see the action in meters. Unfortunately, if you're also using a Zen with that Nex7 (like we are), you'll get usually two exposure for each action point. A pain. Almost as much as the fact the iOSD won't record time stamps for syncing the photo's gps data! Arrrrg! Still using a data logger.

    Quote Originally Posted by pls4air View Post
    is anyone familiar with the GS photometry servo setting to trigger the camera? we are using sony nex 7. i can take a picture by clicking trigger and reference photo but it will not take photos automatically in flight. i can click reference photo while we are in flight to take pics but really need it to take pics at the planned times.

  10. #20
    Pilot Extraordinaire
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    Originally Posted by pls4air
    is anyone familiar with the GS photometry servo setting to trigger the camera? we are using sony nex 7. i can take a picture by clicking trigger and reference photo but it will not take photos automatically in flight. i can click reference photo while we are in flight to take pics but really need it to take pics at the planned times.


    Hi,
    first you need fill all data for Photogrammetric , sensor size, overlap H and W, lens, altitude, etc.
    Next you can scan area and preview, in this point you can see a numbers of photos will be take (if you can see this the camera will be takea pics in flight).
    If you agree push export and edit again altitude, h speed, v speed, turn mode, etc.
    Save and upload a mission and GO...

    I hope my explanation helps you....

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