I'm hoping someone can answer a couple of questions regarding the geo referencing function of mission planner. I have a fairly large dataset of some vertical imagery taken recently which I'm having trouble accurately geo tagging.
The main reason for this is there is a discrepancy between the number of images vs the number of trigger events. In all of the flights there are more trigger events than images, which means that geo tagging via the CAM event function of mission planner always fails. I can load the pixhawk log file straight into the processing software (Pix4d) but it assumes that the cam events match the number of photos. They have confirmed that if there are consecutive photos missing from the middle of the batch for example, that it will simply assign the Cam event to the photo in the line, thereby giving it the incorrect co-ordinates.
My second problem is that I deleted the first few images which were of the aircraft on the ground, and this means the time offset estimate will be slightly out as well.
A couple of questions.
1. I have calculated the offset between the camera internal clock, and the GPS time by taking a picture of GPS time off an Iphone app for this purpose. Is it possible to then apply this offset in mission planner?
For example, if an image was taken at X time and the Offset calculated to be Y number of seconds, go back through the log and get the GPS time or the nearest CAM message time and location based on this offset? I can do this manually however it is a tedious task.
I've tried inputting this offset and running it and it looks ok from Mission planner, but it seems to be out when Pix4d processes it.
2. Currently, my understanding is the time offset function looks at the time the first image was taken, and at the time the log was first created. Is this when the pixhawk was turned on and started logging? Is it from when the aircraft was armed? Or is is the from the time it first received a valid GPS signal.
3. Does anyone have a better way of currently doing this?