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Author Topic: Upright orientation  (Read 3152 times)

maddin

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Upright orientation
« on: January 25, 2017, 12:19:11 PM »
When taking pictures with a DSLR, the EXIF data encodes which of the image edges points downwards (gravity vector), right?

It would be nice if PhotoScan would use that information to determine the initial orientation of the point cloud, such that vertical 3D features are parallel to the "up" axis in PS.

Alexey Pasumansky

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Re: Upright orientation
« Reply #1 on: January 25, 2017, 12:22:17 PM »
Hello maddin,

Which EXIF tag you are speaking about? Does it work with arbitrary camera orientation?
Best regards,
Alexey Pasumansky,
Agisoft LLC

maddin

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Re: Upright orientation
« Reply #2 on: January 25, 2017, 01:03:45 PM »
Which EXIF tag you are speaking about? Does it work with arbitrary camera orientation?

I don't know the specific EXIF tag (I guess it's the Orientation tag), but there is one that tells you whether the image was shot in Portrait or Landscape mode (and if in Portrait, which turn). It essentially tells you which edge of the image is "down".

Edit: Here is an illustration of what the tag does.

Couldn't that be used to set up some sort of initial orientation, such that "image up" is the same as "PhotoScan Up"?

BTW, which axis is "up" in PhotoScan?
« Last Edit: January 25, 2017, 01:07:15 PM by maddin »

Alexey Pasumansky

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Re: Upright orientation
« Reply #3 on: January 25, 2017, 01:23:00 PM »
Hello maddin,

Orientation tag is read by PhotoScan and is used for the visualization purposes (the image is rotated in the Photo view accordingly).

For unreferenced complex projects the orientation of the coordinate axis in the Model view would be arbitrary can cannot be predicted.
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Alexey Pasumansky,
Agisoft LLC

Grischa Hahn

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Re: Upright orientation
« Reply #4 on: January 26, 2017, 01:52:21 PM »
I think the computation of a good estimation of the worlds up-vector from cameras + orientation tags is not so complicated. ReCap Photo does this. Capturing Reality does this. Pix4D does this. And: it is very helpfully.

+1 from my side.

Lazar Obradovic

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Re: Upright orientation
« Reply #5 on: March 31, 2022, 05:34:30 PM »
Coming back to this thread:

Which EXIF tag you are speaking about? Does it work with arbitrary camera orientation?

I know Metashape is using GPSPitch / GPSRoll tags, but I’m not sure if they alone can be used, or only when other GPS tags are present as well. I currently don’t have a camera that exports those tags, so can’t tell.

In addition, Gopro exports gravity vector data (https://exiftool.org/TagNames/GoPro.html) even in JPEGs, and so does Apple for iPhone photos (https://exiftool.org/TagNames/Apple.html).

All of these can be used to tell where is “down” and possibly assist camera pose estimation algorithm (by at least suggesting 2 of 3 angles).
« Last Edit: April 06, 2022, 10:44:27 PM by Lazar Obradovic »