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strawlab / strand-braid

Live, low-latency 2D and 3D tracking from single or multiple high-speed cameras
https://strawlab.org/braid/
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Empty archive when saving AprilTag #6

Closed elhananby closed 3 years ago

elhananby commented 3 years ago

Hi Andrew,

I tried using the apriltag detection for calibration, and I can see that it detects the tags successfully for the cameras and saves a zip file. The zipfile contains an csv file, however if i try to extract it I get an empty archive error; if I try to open it from within the zip, it shows only one row with Chinese characters.

edit #2: nevermind, realized I was just being dumb and opening the csv with the wrong encoding. I am now able to open the csv file from within the zip, but still not extract it.

edit: I also tried using the alternative (using gst-plugin-apriltag), however then I get an error: ERROR: pipeline could not be constructed: no element "filesrc". I made sure to run export GST_PLUGIN_PATH='pwd'/../target/release and install all required gst-streamer packages.

Thanks for all the quick help! Elhanan

astraw commented 3 years ago

How are you trying to read the apriltags.csv.gz file? Pandas should be able to open it directly (despite being gz compressed) with:

pd.read_csv('apriltags.csv.gz', comment='#')

what's the error you are getting?

For gstreamer, if filesrc cannot be found by streamer, it seems you may be missing some of the core plugins. Can you tell Ubuntu to install more of the gtreamer packages?

elhananby commented 3 years ago

Yeah, I eventually did just that, and it opened it with pandas correctly (although I had to specify skiprows=8 due to some additional rows at the beginning of the file) and performed the calibration successfully. Should I expect similar reprojection error values as with MCSC? I got around 1.5 for 800x600 cameras and ~4 for the HD cameras.

Regarding gstreamer, I will check it again a bit later and let you know.

Thanks, Elhanan

astraw commented 3 years ago

As this is wandering a bit from the original issue and also is more of a discussion topic rather than an issue per se with the Strand/Braid, I would prefer to have this conversation at our group. I answered the last question about reprojection errors at https://groups.google.com/g/multicams/c/IwWpcpQaA84.