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Author Topic: failure to assign marker points  (Read 3255 times)

borghi_gianmarco

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failure to assign marker points
« on: May 05, 2023, 12:03:57 PM »
Goodmorning, I'm trying to resolve this problem by my self but I don't obtain any results so I ask your help.

I have to create a model of a tomb but when I align the images Metashape doesn't recognise some areas of the image. I controlled and it seems that there is enough overlap and it seems that my professor taked in the right way all the images (he moved himself during the acquisition for obtain different points of view).

I also tryed other way to resolve this problem:
1. Using DxO viewpoint I corrected the geometric distorction of the image. I tried the alignment only with this image and  also in a separated chunk with the original snapped (I think in that way I can elude Metashape making it to "think" that I take the photo with different point of view).
2. Using PTGui I tryed to create a panorama of the wall but it didn't work;
3. I tryed with the calibration of the lens;
4. I created new photos with Photoshop to increase the overlap in the areas with this problem but it didn't work. I also tryed to add the images corrected with DxO but it didn't work.
5. During the alignment I used different setting but I have always this problem.

What can I do?

Thank you.

G.B.

tazzo

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Re: failure to assign marker points
« Reply #1 on: May 05, 2023, 12:48:53 PM »
Hello Gianmarco,

Can you share the dataset?

1. Metashape will undistort images, trying to correct them will result in worse results
2. Don't touch the original images, because by creating a panorama EXIF information will screw-up
3. To calibrate the lens you need a checkboard at the same focus-distance of your pictures, and the same camera/lens of course
4. Try to add some manual marker in metashape to help the alignment (pro version only), but don't do anything with Photoshop, DxO, or any other software. Changing the geometry / metadata will create issues.
5. Stick to the default settings for now

borghi_gianmarco

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Re: failure to assign marker points
« Reply #2 on: May 06, 2023, 11:00:37 AM »
Hi! Unfortunatly I can't share the images because it's a University of Milan's project, best I can is share here some pictures taked by my mobile phone of the Metashape's interface.

I forgot to put in the list that I also tryed with markers, insert by myself on the critical areas and on the target put in the scene. The calibration of the lens I used the same camera with the same focal lenght with the same filters (it's a modified camera for multi-band imaging).

I did all those tests because I tryed with the "right way" but it didn't work and unfortunaly we can't retake the photos so I'm trying to obtein the best with them.

tazzo

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Re: failure to assign marker points
« Reply #3 on: May 06, 2023, 01:21:26 PM »
If you can't share the dataset in public, you can send me a PM with a link or something if you want I have a look.
At this point I guess there should be something wrong in the dataset, maybe not enough patterns or too much vegetation. You can try to do an aligment at medium, low or lowest quality in these cases.
To align a picture with markers, you need at least 4 markers.
Cheers,
Ciao!

borghi_gianmarco

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Re: failure to assign marker points
« Reply #4 on: May 07, 2023, 12:16:39 PM »
Hi Tazzo! Unfortunatly I can't share the dataset but only those attachment.

I controlled the dataset and It seems ok, maybe It isn't perfect but I thinked that It can be done.

If you take a look ti the images you can see that metashape doesn't recognise some areas of the images. I also tryed with other quality but is the same result. I put 44 marker between target and placed by myself in metashape.

Best regards.

G.B.

JMR

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Re: failure to assign marker points
« Reply #5 on: May 07, 2023, 12:57:16 PM »
I have the impression that your images do not have enough overlap, it seems overlap is under 50% and that leaves areas with zero overlap and that will make impossible to reconstruct. Is an image is reluctant to align but you are positively sure that it overlaps with aligned images, then you need to place at least 5 markers in that particular image connecting it to aligned ones.
José Martínez
Geobit & Accupixel
Metashape training

tazzo

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Re: failure to assign marker points
« Reply #6 on: May 07, 2023, 01:22:30 PM »
You have some walls that can be problematic to align because few patterns. Images seem very close-up and this won't help too.
After putting markers you have to run the alignment again. Be sure to confirm all blue flags, are automatically created but need to be confirmed.

Try to align images multiple times without changing parameters and without resetting the alignment.
Have a look if the software created many components that you can merge at some point.

If everything doesn't work, I guess you have to take pictures again in a better way.
« Last Edit: May 07, 2023, 01:24:47 PM by tazzo »

borghi_gianmarco

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Re: failure to assign marker points
« Reply #7 on: May 07, 2023, 01:29:36 PM »
Goodmorning, thank you for answer me on Sunday!

If the images haven't enought overlap why Metashape can relate  the upper part and the down part of the image with other images meanwhile the center is empty of marker point (image 3)?

In the 4° image I put 6 markers but he can't align, I can't understand why... for example near the point 7 it found some tie point but it can't relate the image with the other.

I will try to realign without reset, maybe in this case it can be usefull to split the project in more chunk and align them, isn't it?

Best regards,

GB

tazzo

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Re: failure to assign marker points
« Reply #8 on: May 07, 2023, 02:09:54 PM »
Hello Gianmarco,

Happy Sunday!

If you put 4 marker on an image and you align it again, the NA text will go away, but tie points won't appear, you need to do a full alignment for this.
Markers should ideally be on different planes and not too close.

If can't align with 6 markers is because some markers are wrong and there is a conflict somewhere.

Can you see "holes" by enabling the "Show cameras" button? For an example please see the attached image, camera are spread around the object from ground and there are no horizontal holes.

In the component folder you should have a single item, please see the second image.

Splitting the project in chunk can help in some cases, where the light changed during the image acquisition. But I try to avoid this way as much as I can because more distortion may be introduced and you can have less tie points.

borghi_gianmarco

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Re: failure to assign marker points
« Reply #9 on: May 07, 2023, 03:41:08 PM »
Hi, in this message I'll attach the screenshots of my work, it seems that we had coverd the entire space and I have a single item (as in your second photo). The only images that aren't aligned are at the entrance of the tomb, so the other images are aligned but the model still have the holes.

For the targets: at most I think that I can mistake the position between two image of some mm, not positioning them in a total wrong place. Is Metashape so sensible to a little mistake?

Thank's everybody.

GB

tazzo

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Re: failure to assign marker points
« Reply #10 on: May 07, 2023, 09:59:24 PM »
If you rotate the camera and take multiple pictures from the same position you can create a “station” folder in Metashape. The camera pattern doesn’t look ideal anyway. You can try to return onsite and take additional pictures. Few millimeter should be fine for your marker alignment.
« Last Edit: May 07, 2023, 10:02:03 PM by tazzo »

borghi_gianmarco

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Re: failure to assign marker points
« Reply #11 on: May 07, 2023, 10:05:00 PM »
Goodevening, thank you for all. Probably we can't retourn inside to retake the image but it's important to know that the problem is the dataset and that we can't do any type of procedure to fix it.

Best regards.

GB

tazzo

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Re: failure to assign marker points
« Reply #12 on: May 07, 2023, 11:19:15 PM »
You can try many things suggested, but if nothing is working there is nothing to do here. You can try another sfm software to see if you get something.