Problem with markers

[Alterco]

Hi,

My problem occure with a scene where I used georeferenced targets (surveyed with a tacheometer) to georefence my 3d model.

First, I have run photoscan to align, build geometry and produce texture with my set of images.
The process goes to the end producing a quite good 3D model.
The geometry seems to be accurate.

Then, I switch to the ground control markers creation mode to create the markers on my targets to next declare the real coordinates.

So, I create the markers by pointing them on the photographs where they are visible.
Looking to the markers in the point cloud, it seems that some markers are well positioned whereas others are completely at a wrong place...
Then, when I set the georefenced coordinates, the result is not good (looking for the alignment of different 3D models supposed to be all georeferenced in the same system).

Finally, the problem seems associate with the misplacement of some markers.
I could only keep the markers that seems well placed but doing this I wonder if my model is really accurate. Moreover, the georeferencing seems remaining inaccurate when I look to the others georeferenced parts.

Does someone have encountered the same issue ?
And what can I do or test ?

Thank you in advance for your help.

Adrien A.

[frank.stremke]

try to stik to the worrkflow as described in the tutorials on the website for using ground control.
also it seems to be much more acurate to place the markers on the photo instead of the model...
best regards
frank

[Alexey Pasumansky]

Hello Adrien,

Please check projections for every marker (it is easy to filter photos that contain projection for selected marker using Filter by Markers button on Photos pane toolbar).
Probably some images were not aligned correctly, however, could you please provide a couple of screenshots of the 3D view?

[bisenberger]

Can you provide more information on this type of survey? Are you using a theodolite and stadia rod? What is the size of your area and what accuracies do you expect from this type of survey?

[Alterco]

Thank you for your answers.
I have managed the situation by using set set of images that is working.
Apparently, as you said some photos were not well aligned (I do not understand how because the global model seems ok...).

To bisenberger : I used a total station to survey my targets. It allows me to georefenrence the global model and gather all the parts of my different model in the same system.