jallison

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Posts posted by jallison

  1. 11 hours ago, 20kN said:

    I am not sure that winning in PPC speed, time and distance makes you the best wingsuit pilot in the world anymore than having the longest swoop makes you the best canopy pilot in the world. There is a lot more to it than that.

    Competing is fun. Seeing people compete is fun. The OP wants you to click a link and get stoked, there is no more to it than that.

    • Like 1

  2. Thanks for you help, folks.

    I've concluded that no matter the processing, the data will never be nearly as rich coming from a gopro as it is in a Flysight log. At least I tried!

    I got myself a Flysight, and I am now very happy with my logs :)

  3. · Edited by jallison

    I figured I should make my own parser to output a CSV similar to that of a Flysight, so here goes : 

    https://github.com/j-allison/gopro-to-flysight

     

    Before (using data from the util cited above: https://tailorandwayne.com/gopro-telemetry-extractor/) : 

    image.png.43d23957a5419f31c30d2c1d8275ddc7.png

     

    After using my parser, based on `gpmf-extract` and `gopro-telemetry` libraries: 

    image.png.a36124dfc02397595c7997622e2bee9d.png

    I'm feeling happier with those results; they seem to be way less "smoothed out". Still work in progress. 

    (Is it outrageously wrong to calculate N/E velocity components by using lat or long difference over time difference from point A to point B ? :D)

    • Like 1

  4. I'm realizing as I read you that I'm relying on my GPX data without questioning its origin. Here's how I proceeded: 

    1. Extracted raw data from mp4 into a raw file, using ffmpeg : 
      ffmpeg -y -i "/path/to/theFile.MP4" -codec copy -map 0:3 -f rawvideo outputFile.bin
    2. Used the "gopro2gpx" util from this repo to parse raw data into gpx :
      https://github.com/JuanIrache/gopro-utils

    Here's where I was wrong - step 1 preserves all data. Step 2, not so much. I overlooked the fact that it might leave data behind while parsing the binary extract into gpx.

    So I'm currently trying out this other util (slower, in JS) : https://github.com/JuanIrache/gopro-telemetry

    And... I seem to get a 3D velocity! I get a more thorough output in JSON, I still have to convert it to gpx though. Files attached, work in progress! Also included, GPS data in CSV.

    Fun stuff!!

    chablais.json

    chablais.raw

    flares.json

    flares.raw

    GH010928-gps chablais.csv

    GH018648-gps flares.csv

  5. 36 minutes ago, crwper said:

    My guess is that the GoPro is using GPS only at 18 Hz. This could be confirmed by looking at the number of satellites used in the fix (assuming this is reported). If you see a number around 8-12, it's likely GPS only. If you see a number more like 12-18, it's probably tracking GPS and GLONASS.

    Spot on. Thank you for the simple explanation on different constellations. The gps fix is nowhere near 12-18, I've consistently had a value of 3 (best case scenario). 

    37 minutes ago, crwper said:

    There is one other thing I would pay close attention to. One of the things I like most about the u-blox module inside the FlySight is that it reports 3D velocity, so there is no need to calculate velocity from differences in position (which is notoriously error prone).

    Again, you're absolutely right. There's no 3D velocity in the GoPro's data so it has to be calculated from position afterwards. Far from ideal.

    Thank you so much for clarifying those points, that's exactly the kind of precision I was hoping for. 

  7. Thanks for the input. 

    I'll take 18Hz over 5-10 anytime, more data can't hurt in this context.
    Ease of use: I've made a script on OS X - drag and drop mp4 file onto it -> outputs a .gpx -> ready to import in any analysis website or software :)

    No audio feedback: good point, I'll have to try this out when I can get my hands on a flysight!

  8. Posted · Edited by jallison

    I recently managed to extract GPS data from my GoPro hero 7 footage. I was in the market for a Flysight unit but I think I might reconsider now.

    The (crappy) GoPro Quik app used to tell me my footage hadn't recorded any GPS data for lack of satellite fixes. That doesn't seem to be true as there actually is data attached to the mp4 files.

    1. Use https://tailorandwayne.com/gopro-telemetry-extractor/ to extract data from the mp4 file
    2. Export to .gpx file
    3. Import in baseline.ws, or Flysight viewer, or whatever gpx interpreter app

    Now for the nerdy part. I've never owned a Flysight unit, nor analyzed any data coming from one. But according to the specs, it seems to output data at a ~5Hz rate, whereas the GoPro GPS chip writes ~18Hz worth of data. That's more than 3 times the rate of a Flysight.

    There seem to be a few outliers here and there, but overall I'm pretty impressed with the GoPro's GPS feature. I wouldn't have bet on this level of accuracy. Especially coming from a device that freezes out from time to time, or chews up a whole battery while powered off.

    Here are a few acro lines (Funk 3):

    And a Freak 2 (heli skydive) line over the swiss Alps:

     

    Flysight nerdy users: what's your take on this? Does the data from my GoPro seem reliable? Are there too many outliers compared to a Flysight?

    • Like 1

  9. 23 hours ago, roguender said:

    Wingsuit jumps : 13 on an S-fly Indy

    I'd hate to be the party pooper here, but buying an S3 seems to be a huge step-up from 13 jumps on an Indy? Maybe you should check with your mentor if there are any intermediate suits to rent nearby, Versos, Hawks or similar older "French level 2" suits?

    The Indy is a great suit to start for your first jumps. But it's an old, low-pressure design. Your position when pulling from an Indy won't matter much. The S3 on the other side, is a race car in its own category, not to be underestimated. 

    Again, check with your mentor. You're in for another 7 jumps before you can get your "niveau 2" anyway ;) 

    • Like 1