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Author Topic: Alignment of Cameras Creates Infinity Spread-Any Help  (Read 2902 times)

KGidusko

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Alignment of Cameras Creates Infinity Spread-Any Help
« on: July 05, 2016, 07:57:37 AM »
Hello, new to the forum, but thought I would give it a shot; if I forget to include important information please let me know so I can be a better forum poster.

I have been attempting to model a prehistoric piece of pottery. I took the photos in a lightbox and manually turned the pot. I cannot seem to align the photos. Instead I get this spray of points emanating from a center point. Any idea what is going on? Any tips to make this work?

[img]http://[Imgur](http://i.imgur.com/eyG5icE.png)
[img][Imgur](http://i.imgur.com/jecYnwU.jpg)

stihl

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #1 on: July 05, 2016, 12:07:26 PM »
I believe the issue is that the only thing that's moving in your images is the pot itself. The camera and the rest of the environment stays stationairy. Photoscan realizes this and places all the camera positions at the same position (as it happened in reality).

Perhaps masking your images so that the background is completely cut out would probably fix the photo alignment.
Otherwise create a setup where the pot doesn't move but the camera does.
« Last Edit: July 05, 2016, 01:41:47 PM by stihl »

Alexey Pasumansky

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #2 on: July 05, 2016, 12:14:36 PM »
I agree with stihl, it seems that the issue is related to "turn-table scenario" used without masks applied to the static background.
Best regards,
Alexey Pasumansky,
Agisoft LLC

KGidusko

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #3 on: July 05, 2016, 03:53:43 PM »
Thank you both for the responses. I'd tried some basic masking, but I will go in and do a better job. I realize I messed up by not having any other points of reference. IF the masking doesn't help is there anything anyone can think of to get this set of images working? I won't have access to the pot again for some time. If all else fails, I'll just have to retry capturing images.

Alexey Pasumansky

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #4 on: July 05, 2016, 04:08:35 PM »
Hello KGidusko,

You can send the link to the dataset to support@agisoft.com and we'll see what result can be achieved from the images.
Best regards,
Alexey Pasumansky,
Agisoft LLC

KGidusko

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #5 on: July 05, 2016, 05:19:07 PM »
Alexey, I have sent the photos via google drive to the support email. Any help or insight is very much appreciated!

I really thank you for what a great community of assistance you have here. It's one of the reasons we recommend you to anyone looking to get into photogrammetry.

Best,

Kevin Gidusko

Alexey Pasumansky

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #6 on: July 05, 2016, 08:54:11 PM »
Thank you for providing the sample dataset.

I've added more accurate masks to the images and got the photos aligned, I've sent the project file to you by e-mail.

There are some general recommendations that I'd like to share to improve your next projects (also might be helpful for the others):
- try to use the image space more effectively, now only about 10% of the image space is used;
- use lower ISO to minimize the noise level;
- also check the aperture and focusing, as the images are not very sharp and the details on the surface are blurred,
- try to improve the lighting conditions and use more soft and uniform light, currently the same areas on the object's surface appears to be dark and bright on different photos, that may affect not only the final texture, but also the alignment process;
- keeping the same focal length for the whole shooting set is recommended, though the use of the different focal length in the same project is acceptable;
- mask creation can be automated in case for every fixed camera position you take the "empty" image of the background only without the object, then you'll be able to use Tools Menu -> Import Masks -> From Background option to generate the masks automatically.
Best regards,
Alexey Pasumansky,
Agisoft LLC

KGidusko

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Re: Alignment of Cameras Creates Infinity Spread-Any Help
« Reply #7 on: July 06, 2016, 04:55:46 PM »
Alexey,

Thank you very much for the insight and for taking the time to look at the pics I send. I really can't tell you how much help that has been!

I think I definitely have a better understanding of how to set up a project in the future and have a better idea of info I need to learn.

Many thanks!