I’m new to ArduPilot but have a lot of prior experience collecting, georeferencing and mosaicking UAV aerial photos using other autopilots (chiefly MicroPilot).
I note that ArduPilot has a very handy dataflash logging option (“CAMERA”) that will record all the geotagging info you need each time the autopilot triggers the camera. Therefore in theory, automating the process of geotagging the photos should be a simple matter of reading the dataflash log, extracting the necessary numbers from each one of the “CAM” lines, and matching them up with the corresponding photos in the correct sequence.
That’s why I’m frankly puzzled when reading the instructions on geotagging images with Mission Planner (http://plane.ardupilot.com/wiki/common-geotagging-images-with-mission-planner/) over the need to estimate time offsets and positional offsets, and I also can’t figure out why on earth you would use the telemetry log to geotag photos when using the dataflash log with the CAMERA option enabled would seem much more straightforward. With the latter approach, there should no need to even know the time that anything took place or worry about positional offsets; again, simple matter of matching the data from the “CAM” lines in the dataflash log with the corresponding sequence of photos.
Is there in fact a way to use the “Geo Ref Images” tool in this much more straightforward manner that isn’t covered in the instructions? Any enlightenment would be very much appreciated. Thanks.
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Thanks for the reply, iskess. I was beginning to suspect as much. I can see how the time offset approach would be useful in the absence of cam logs and in cases where the camera isn't being triggered by the autopilot.
The promising news is, I also posted this same comment on the APM forum and it looks like I may have convinced one of the developers to look into adding a "geotag from CAM logs" feature to Gef Ref Images tool.
Cheers.
Hey Dominique,
the "CAM-trigger feature" ist based on some of my ideas, i posted them nearly one year ago in this forum. It was added very fast to the main code, but the additional tools are still missing.
Your ideas are great, and in my opinion it is the right and best way to geotag images taken with arduplane & arducopter.
Try to post a issue on the ardupilots github repository, write to tridge and michael o. to have a real chance for a change :-)
(https://github.com/diydrones/ardupilot/issues)
Best regards from Germany,
Yannick
HUH! APM mission planner just released again hardly abandoned..
HZL
Michael does a fantastic job keeping MP up to date with innovations. Someone else wrote this tool.
Ok, upon reading another related discussion further down this category, I realize that what I referred to as "positional offsets" (actually called "log offsets" in the Geo Ref Images dialog box) are simply a means of specifying the order in which data appear in the log file. Got it.
Still, my question remains: why is any of that necessary, in particular the time offset, when it should be a simple matter of grabbing the data straight from each "CAM" line?
Unless there's indeed a way of doing that with the Geo Ref Images tool, for the sake of precision I would actually rather manually grab the data from the CAM lines in the dataflash log file myself than rely on this bizarre convoluted approach based on estimating time offsets.
@Dominique,
Would you pls add a link to the relevant page explaining those positional offsets or simply explain in a few words ?
Thank you.
+1 for this after having to explain to a user how to geotag his images.