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Thread: Z-Acceleration/GPS Accuracy

  1. #1
    Tuner in Training
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    Dec 2018
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    Z-Acceleration/GPS Accuracy

    I am in the process of possibly changing from a Garmin VIRB Ultra 30 to a GoPro Hero 7 Black. As the GoPro software is all but unusable, I have purchased RaceRender. It is a nice product. My testing has (so far) brought up 2 issues.

    1) Z-Acceleration. In my videos I like to show the G-Force which would be the Z-Acceleration and would normally be 1G (or 9.8m/s/s). This field is not imported from the GoPro video by RaceRender. I realize this is most likely due to the automotive origins of RaceRender but this is field of interest for aviation videos. How can I get access to this field?

    2) GPS Accuracy. I have an issue with displaying a track map where rather than showing the path taken, it shows up as a straight line. I believe this is an issues with the GPS data coming from the GoPro. I appears that some of the GPS data points are erroneous and the track shown is a result of a route to/from an (or several) erroneous (and distant) GPS positions with the valid GPS positions "compressed" into a very small section on the map.

    I believe that this can be solved by identifying erroneous GPS positions based on GPS Accuracy below a definable value or speed in excess of a certain value. Any ignored GPS position(s) should be set to the last "valid" position. This could be done either at the import level or possibly within the trackmap component itself.

    Glenn

  2. #2
    Advanced Tuner
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    Apr 2018
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    Regarding question 2, I've noticed irregularities when the "Lap Time" is close to 0 for several laps. Given that you're using the GoPro itself for data, I'm not sure there's much that you can do. If you use TrackAddict or similar in the future, then you may be able to export into CSV and modify however you like afterwards. I personally use RaceChrono, but add additional fields into the output through a separate program so that I can have access to fields such as Boost (which is just Manifold Pressure - Ambient Pressure). I know that Track Addict provides several "Acceleration" fields, but not sure how well the Z-Axis is supported since it's a racing focused platform. Maybe providing a file would help?

  3. #3
    Tuner in Training
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    Dec 2018
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    HoboBob,

    As far as I can tell, Race Render uses an external program (Open source I believe) to separate the data from the GoPro video into a text file. It shows up after importing the GoPro video file into RR.

    I believe the Z-Accerlation data is there as well as the GPS accuracy. From what I can see, I don't believe that RR uses these fields. Given that RR uses several other fields from the exported data file, it should not be too difficult to get access to Z-Acceleration and GPS accuracy as well. In reading through the forums they are other posts related to erroneous track maps. I think this is related to "bad" GPS data and can be solved by ignoring GPS locations with poor GPS accuracy.

    Glenn

  4. #4
    Advanced Tuner
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    Apr 2018
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    Until there's official support, you could try using something open source (like https://github.com/JuanIrache/gopro-...aster/GPMD2CSV) to extract metadata into CSV format. From there, you should be able to use whatever columns were extracted once you add it to RR and sync it up. This could also potentially solve your multiple video/track map issue as well if you just concatenate the four CSVs together. It's not ideal...but it might get you by until there's better auto-extraction support.

    I've got a Session 5 which doesn't include GPS; so I haven't really explored GoPro metadata extraction in depth. I just use an external GPS instead.

    When you do finally get the fields that you're looking for, I highly recommend checking out the APIs for the Enhanced Script Editor: http://racerender.com/RR3/docs/DispObjEnhanced.html
    You can do some pretty powerful customizations to the gauges. I was able to create some Formula 1 style lap lists and a temperature gauge that almost exactly matches my actual dashboard: https://youtu.be/oWIO6xbxga8

  5. #5
    Tuner in Training
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    Dec 2018
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    I have already made my own gauges with the script editor. As a software developer it was pretty straightforward and a good tool. I went there first to see if I could resolve the issues I was having but unfortunately, the script editor does not have access to the data fields required.

    Thanks again,

    Glenn

  6. #6
    Potential Tuner
    Join Date
    Jun 2021
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    Quote Originally Posted by HoboBob View Post
    Until there's official support, you could try using something open source (like https://github.com/JuanIrache/gopro-...aster/GPMD2CSV) to extract metadata into CSV format. From there, you should be able to use whatever columns were extracted once you add it to RR and sync it up. This could also potentially solve your multiple video/track map issue as well if you just concatenate the four CSVs together. It's not ideal...but it might get you by until there's better auto-extraction support.
    Any update on plans to incorporate z-axis accelerometer data into RR?

  7. #7
    Potential Tuner
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    Mar 2023
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    To me it just sounds like the GPS data was bad. Is there way to independently confirm the GPS data? Sounds like the gopro has some internal accelerometers that are trying to propagate your position, explaining the straight line motion.