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Author Topic: image error while marker placing  (Read 1211 times)

mauroB

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image error while marker placing
« on: September 01, 2023, 08:01:45 PM »
Dear All,

I'm working with a project which must be georeferenced. For that, during the image capture we placed non-coded cross-type target within the study area.

I perform a preliminary alignment by using a reference calibration fixed (I planned to loose the camera parameters only at the end of workflow, during the final block optimization). Then, I used the tool for the automatic marker detection and matching. At the end of the computation, in the reference pane, all detected markers were displayed along with an error (pix) different from zero...

Considering that after applying the detection tool I did not perform any least squares adjustment or manual refining of (automatically) identified projections, I was wondering what the errors actually represent. At most, I could expect an image error equal to 0, since the projections are those identified by the software, and in any case "an error metric not in the least-squares sense"...

After that, I performed the same test, by using the guided approach for markers placing (i.e., "add marker" comand). Also in this case, after manually adding markers on aligned photos I get projections errors different from zero...

Not convinced by the results, I finally performed the adding of only one marker projection through the manual approach (i.e., "place marker" comand). With only one projections placed, the software returned an image error (also in this case different from zero).

It absolutely makes no sense...

Any idea?
Does the software automatically perform a least-squares-based triangulation (i.e., forward intersection) after placing marker on the images?

P.s. I'm working with Metashape v.1.5.1

Regards,
Mauro

« Last Edit: September 02, 2023, 04:24:19 PM by mauroB »