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Author Topic: New and still wondering...  (Read 2521 times)

parry

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New and still wondering...
« on: May 26, 2021, 09:42:12 PM »
A group of us (probably not reading the manual enough) have been working with Metashape and Ubuntu.  Using a GeForce GTX 1050 Ti with 4 GB memory we just cannot get a  (any) group of photos to align properly, We learned that taking photos from one location and pivoting around that location does not work (its in the manual), we learned that although it would seem easy to rearrange the photos in the workspace to better enable the sequential aligment, we could not find any way to do so without renaming them(prepending 1,2 3 etc), we learned that Ubuntu 20 with the latest nVidia drivers has a bad memory leak and crashes the rendering process to the point of chewing up 20 GB of memory and providing no errors and we learned that an mp4 video cannot be imported and throws a "The QMediaPlayer object does not have a valid service -  which seems to indicate that the player is not opening the file.   All in all this has been quite a frustrating experience. After some 300 hours of playing with images of all kinds we still don't understand how to make metashape 1.7.2 work properly with a set of photographs. Why when we add images does it say the images are not calibrated for example (NC) ? Why when one looks at a sequential set of images to the human eye it appears that we have captured the right images for aligment. Perhaps if there were a reference set of photos that represented a building of some sort with explicit instructions to build a model out of them that might help.   What does it take to understand how this software works and how to optimise the image capturing process so that the images are best optimised for alignment.  What exactly is the alignment process looking for ? It appears that most of the time the mapping of images is from colour point to colour point not from geometrical structure to geometrical structure.  We find that if you have a stucco wall the alignment is excellent, but if you are looking at longer frequency geometric structures then its not so great.  Any advice would be gratefully accepted.   Thanks !

Alexey Pasumansky

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Re: New and still wondering...
« Reply #1 on: May 26, 2021, 10:10:09 PM »
Hello parry,

It would be helpful, if you could share any problematic project with the alignment results that you've got so far (with the original images) to support@agisoft.com, so that we could check it on our side.

If you are observing any crash or high memory consumption, saved processing log related to the problematic operation would help us to understand the issue better.

"The QMediaPlayer object does not have a valid service" - may indicate to missing system video codecs, so to investigate this problem we would need any example of short video fragment that cannot be opened by Metashape and the version of distribution that you are using.

Some information about image capture tips can be found in the related section of Knowledge base:
https://agisoft.freshdesk.com/support/solutions/folders/31000117943
Best regards,
Alexey Pasumansky,
Agisoft LLC

parry

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Re: New and still wondering...
« Reply #2 on: May 26, 2021, 10:37:00 PM »
Thanks for the quick reply Alexey.  I am afraid between 2 of us, we have never been able to get a decent alignment of any specific group of images.  Nonetheless, I will send what we have  -  unfortunately, this will have to be in a group of emails unless you have a repository for us to upload to.   We will of course do this.  Additionally, there is no error log of any kind that I can find when the system crashes because of rapid growth of memory usage in Ubuntu 20.  There is no metashape crash log, and the system log does not show anything.  I have tried to find an nVidia log but that does not exist either.  I started monitoring memory usage with top  in Linux and we just see the % of memory usage climb to > 80% at which point the disk is thrashing and the system hangs.    So we have reverted back to Ubuntu 16.  The nVidia drivers for Ubuntu 16 are lower in sequence number than for Ubuntu 20 as far as I was able to install them.  What might be useful for users like ourselves is to get a reference image set, with a set of assigned settings for alignment, cloud generation, texture generation etc.  so we could assure ourselves of our approach and understand what happens when we use different settings.  Then perhaps users could also upload problematic image sequences and we could help each other.  The learning curve is high with this software and there are many places one can screw up.  As for the video my system easily views it with the "videos" application on my Ubuntu 16 system.   For the moment, we have given up with Ubuntu 20 because it always crashes, usually creating a dense point cloud.  Alexey, I am astounded at how much you do all by yourself.  This must be a 24X8 job  ;)

Alexey Pasumansky

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Re: New and still wondering...
« Reply #3 on: May 28, 2021, 12:29:01 PM »
Hello parry,

You can use some file transfer service to send large amount of data instead of using e-mail attachment, I think it should be more convenient.

The processing log can be re-directed to the file via Metashape Preferences dialog ("write log to file" option), in this case the log will be accessible, even if the application is closed unexpectedly. 
Best regards,
Alexey Pasumansky,
Agisoft LLC

Lebobo

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Re: New and still wondering...
« Reply #4 on: May 30, 2021, 04:45:22 PM »
Hi Alexey
Working with Parry on the same data set, I am wondering why there are some parts of the building we are trying to capture that don't show up on the reconstruction. I have tried multiple combinations of options and parameters in the camera alignment and point cloud generation, but one corner of the building is not there (the left corner in the images). The geometry of that corner is fully visible in at least seven photos, but it does not lead to any section of the mesh.
What can cause this?
Note that the same set of photos on another Photogrammetry software (3DF Zephyr) does not appear to be a problem to reconstruct the entire geometry.
Screen shots that describe this have been added to the folder that we have shared with you.
- Thanks.

Alexey Pasumansky

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Re: New and still wondering...
« Reply #5 on: May 30, 2021, 05:13:03 PM »
Hello Lebobo,

If the data has been shared via our Helpdesk system, please specify the ticket number, as it its hard to answer this question without seeing the actual model.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Lebobo

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Re: New and still wondering...
« Reply #6 on: May 30, 2021, 06:48:39 PM »
Hi Alexey,

Thanks for your reply.
The images have been shared in a box folder that Parry created and where you (i.e. support@agisoft.com) you have been invited.
Do you need another way to get the images?
- Thanks

Alexey Pasumansky

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Re: New and still wondering...
« Reply #7 on: May 31, 2021, 01:47:00 PM »
Hello Lebobo,

I have uploaded the new project to the shared directory (to reduce the file size the depth maps have been removed, but they have been generated in High quality with Mild filtering).

The suggested workflow assumes the following:
- limit the key points to 40 000 (for tie point limit you can use 4000, but I've used 10 000).
- adjust the bounding box size after camera alignment to include all the parts of the scene of interest (the missing part in your case seems to be related to the fact that is was outside the bounding box).
- build mesh using the depth maps source option skipping the dense cloud generation.
Best regards,
Alexey Pasumansky,
Agisoft LLC

andyroo

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Re: New and still wondering...
« Reply #8 on: June 03, 2021, 05:24:50 AM »
...What might be useful for users like ourselves is to get a reference image set, with a set of assigned settings for alignment, cloud generation, texture generation etc.  so we could assure ourselves of our approach and understand what happens when we use different settings.

parry and Lebobo - you might find it useful to download the Puget Systems Metashape Benchmark(s) and try them. They have a small and a big one here:

https://www.pugetsystems.com/labs/articles/Metashape-Benchmark-1457/