Pixhawk CAM message offsets?

I've been trying to use the Georef tool to add XYZ data to my photos' EXIF metadata. However, when I imported that into Agisoft Photoscan, I was having alignment issues due to misreported altitudes. 

The Geo Ref tool is reporting a file discrepancy error between the number of CAM messages and images, so I used the time offset option. However, that option is what is giving me the erroneous altitudes.

Does anyone know what the correct CAM message offsets are for a dataflash log from Pixhawk? The default options do not give me the correct altitudes, and I am not finding the info I need in the wiki

http://plane.ardupilot.com/wiki/downloading-and-analyzing-data-logs-in-mission-planner/

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  • Developer

    I too have problems with cam message, made many flights and in every single one I get different numbers of cam message and pics so I get an error in georef tool. Why this happens and how can I correct this? 

    • --I too have problems with cam message, made many flights and in every single one I get different numbers of cam message and pics so I get an error in georef tool. Why this happens and how can I correct this? --

      I don't know what camera you're using, but IT could be the problem. I'm using a Sony NEX7 and had problems with discrepancies as well. There were always more CAM messages than images. I originally expected that it was because of camera focus times, but digging in further I found that my camera cannot persistently capture images when the time between images was too close. By too close, I mean 4 or 5 seconds. It's due to the rate at which the camera can save large files onto the SDcard, at some point it gets saturated and has to stop new pictures from coming in.

      There are three solutions to the problem.

      1. You can see if reducing the size of pictures taken is enough to accomodate the amount of pictures you're trying to capture per minute.

      2. You can vary speed or separating between pictures in order to give the camera more time between captures.

      3. You can purchase a high MB/s SDcard, which can save pictures at a quicker rate.

      I hope this helps.

  • OK, I found the answer to my question.

    http://plane.ardupilot.com/wiki/common-geotagging-images-with-missi...

    But I still think that this information should be updated as well

    http://plane.ardupilot.com/wiki/downloading-and-analyzing-data-logs...

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