About Markers

[fotodimension]

Hi there,

I?ve got some questions about markers:

- When exactly are markers used? Also in Align-process? Or are they only important when aligning chunks?
- What exactly do optimize / update?
- Are markers recommend when not using i.e DGPS? (I mean, when the correct coordinates are not known)

I can scale my model by measuring a distance in real world, defining two markers in my model and entering the scale by hand, I get weird error-values after "updating".

[aphextwin]

nobody can help?

[Alexey Pasumansky]

Hello,

Markers can be used for different purposes:
- georeferencing. When marker has at least two projections on aligned images and have got coordinates specified in Ground Control pane it can be used for referencing. All checked markers are used for georeferencing when Update button is pressed.
- optimization of camera alignment. The same requirement for markers as in previous point. Marker projections and coordinates are included as parameters for camera position refinement. Optimization is recommended for non-linear model distortion removal.
- chunk alignment.
- creating scale-bars.
- helping PhotoScan to re-align the sub-set of wrongly positioned cameras (more detailed procedure is described in User Manual on page 9).

[Alexey Pasumansky]

Hello fotodimension,

I can scale my model by measuring a distance in real world, defining two markers in my model and entering the scale by hand, I get weird error-values after "updating".

Could you please describe this problem?

In case you have unchecked all the elements in Ground Control pane except scale-bars and are inputting reference distance the chunk is no longer referenced in the previously assigned coordinates, so the errors can grow to huge numbers (like the distance to the center of the Earth, for example).

[aphextwin]

That was exactly what helped me understanding markers. Thanks a lot!

Hello,

Markers can be used for different purposes:
- georeferencing. When marker has at least two projections on aligned images and have got coordinates specified in Ground Control pane it can be used for referencing. All checked markers are used for georeferencing when Update button is pressed.
- optimization of camera alignment. The same requirement for markers as in previous point. Marker projections and coordinates are included as parameters for camera position refinement. Optimization is recommended for non-linear model distortion removal.
- chunk alignment.
- creating scale-bars.
- helping PhotoScan to re-align the sub-set of wrongly positioned cameras (more detailed procedure is described in User Manual on page 9).