Messages

1

General / Re: Camera calibration

« on: August 19, 2015, 03:42:49 PM »

If your camera was focused at infinity for the flight, and focused closer for the calibration, then that could explain the problem to some extent.

If this is true, that'd mean calibrating your camera using Agisoft Lens has to be done at the same range as you intent to take photos. Wouldn't Lens loose its purpose then? Since I would have 8 pixels or so on my monitor if I'd take a picture 120m away (assuming I could actually put my monitor outside and still photograph it)

2

General / Re: Camera calibration

« on: August 18, 2015, 05:07:25 PM »

I calibrated the camera using Agisoft Lens, exported that as an .xml file, which I imported into Agisoft Photoscan. I did not rename anything, since I assume Agisoft wrote their programs to work together.

3

General / Camera calibration

« on: August 17, 2015, 06:36:01 PM »

I recently did a survey using a precalibrated camera. When processing in Photoscan, however, when I fix the calibration under Tools->Camera calibration the results are way worse than when I do not fix the calibration. The difference in error is about one order of magnitude.
I suspect this is because if you fix the calibration Photoscan has less degrees of freedom moving things around to obtain a proper fit. Thus, is it better to precalibrate and get large errors, or do not precalibrate and basically do not know what changed?

I just processed the last of the test flights and the result is again interesting. Not fixing calibration gives 1.9m X error, 2.3m Y error and 3.4m Z-error, but when I fix the calibration the errors become 4.6m, 4.5m and 56m. This decreases the flight altitude from 113m to 61m as well, and the fly path was set to be 120m, thus the first is much more likely, considering the terrain is about 7m at its highest elevation.

4

Camera Calibration / Camera precalibration

« on: August 17, 2015, 05:22:45 PM »

I recently did a survey using a precalibrated camera. When processing in Photoscan, however, when I fix the calibration under Tools->Camera calibration the results are way worse than when I do not fix the calibration. The difference in error is about one order of magnitude.
I suspect this is because if you fix the calibration Photoscan has less degrees of freedom moving things around to obtain a proper fit. Thus, is it better to precalibrate and get large errors, or do not precalibrate and basically do not know what changed?