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Author Topic: Why is Image Orientation important?  (Read 1535 times)

scanlab.ca

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Why is Image Orientation important?
« on: October 19, 2017, 07:07:04 PM »
Hi guys,

Something I'm not understanding correctly probably, but why is Image Orientation important (you know that warning that comes up when adding photos)? Isn't flipped image just a transformed matrix?

One way I see when it matters is only when doing Aerial Photogrammetry and orientation may affect how internal algorithms interpret directional motion blur, but for Face and Body Scanning, does it really matter?
Best regards,

Ruslan Vasylev | Scanlab Photogrammetry
S: https://scanlab.ca | E: ruslan@scanlab.ca | T: 1 (778) 991-5157

Alexey Pasumansky

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Re: Why is Image Orientation important?
« Reply #1 on: October 19, 2017, 07:16:39 PM »
Hello Ruslan,

If the resolution of original image is N x M pixels, PhotoScan will put all the images to the same calibration group (providing that they are taken with the same focal length). And the image orientation doesn't matter as long as it is just and EXIF tag, but is the camera is applying this orientation information - you'll get two groups: N x M and M x N and the calibration parameters would be estimated separately. Also this sub-division will raise additional confusion for the 90-degree rotated images - whether they are rotated clockwise or counter-clockwise.

So we usually suggest to disable automatic image rotation by the camera. In other words all the images taken by the same camera should width x height resolution and shouldn't be split into two groups: width x height and height x width.
Best regards,
Alexey Pasumansky,
AgiSoft LLC

scanlab.ca

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Re: Why is Image Orientation important?
« Reply #2 on: October 19, 2017, 08:23:31 PM »
I see, thanks for the prompt explanation Alexey.

Would it be possible to group calibrations where N and M dimensions could be interchangeable, given the focal lengths are identical?
The reason for the request is that it is just much more intuitive to analyze and mask photos in their preferred orientation.


Hello Ruslan,

If the resolution of original image is N x M pixels, PhotoScan will put all the images to the same calibration group (providing that they are taken with the same focal length). And the image orientation doesn't matter as long as it is just and EXIF tag, but is the camera is applying this orientation information - you'll get two groups: N x M and M x N and the calibration parameters would be estimated separately. Also this sub-division will raise additional confusion for the 90-degree rotated images - whether they are rotated clockwise or counter-clockwise.

So we usually suggest to disable automatic image rotation by the camera. In other words all the images taken by the same camera should width x height resolution and shouldn't be split into two groups: width x height and height x width.
Best regards,

Ruslan Vasylev | Scanlab Photogrammetry
S: https://scanlab.ca | E: ruslan@scanlab.ca | T: 1 (778) 991-5157

Alexey Pasumansky

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Re: Why is Image Orientation important?
« Reply #3 on: October 19, 2017, 08:29:00 PM »
Hello Ruslan,

You can manually rotate the images before loading to PhotoScan window, but it is important to rotate them in the correct direction (+90 degrees or -90 degrees).
Best regards,
Alexey Pasumansky,
AgiSoft LLC