Left "eye" distortion in stereo panoramas

Q&A about the latest versions
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NaderF
Posts: 17
Joined: Fri Aug 06, 2021 4:41 pm
Location: US / NYC

Has anyone run into this issue? When using a stereo panorama, either an over/under equirectangular, or a 12 face cube in a strip, there is a noticeable spherical distortion in the left image when viewed in VR.

Both panoramas are from the same scene and they are perfectly vertical, being generated in a 3D software and not with a camera.

When rotating around while viewing in a goggle, the distortion "travels" with the image. A vertical edge becomes bowed as it moves away from the center of FOV. It is quite pronounced when the right eye is closed. With both eyes open, the result is a fuzzy as the more vertical image of it in the right eye overlaps with its spherically distorted image in the left eye. This results in a rectangular door to have jambs that bow in or out as you rotate with the goggle.

This is true in a number of goggles and if a skin with an "Enter VR" button is used, so as to show L and R images in a desktop browser side by side, the distortion becomes obvious.

If you have encountered this issue, have you solved it? If so, is there a setting for the projection from a stereo image, a 12 face cube strip, or an over/under equirectangular image to map close to rectilinear, or to be at least equal, in the both fields of view, left and right?

I don't see such distortion in some of the stereo examples on the website. Is this an over-compensation for distortions inherent in optically produced images? Is there a value that controls this?

Thanks in advance for any suggestions.
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Hopki
Gnome
Posts: 13005
Joined: Thu Jan 10, 2008 3:16 pm
Location: Layer de la Haye, Essex UK
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Hi NaderF,
Firstly thank you for sending your files to support.
I am using a plastic phone holder which is set up to be the same as Google Cardboard.
I can not say I am seeing any difference between the left and right eye, I see the normal barrel distortion but the left is no different to the right.

Using your project I am not really seeing any Stereo effect and after a while, my eyes started to complain.
Testing with Stereo Test images I did not have any real issues with using Cardboard 2014 setting.

This could be simply down to the phone holder you are using, can you say which one it is?
Regards,
Garden Gnome Support
If you send an e-mail to support please send a link to the forum post for reference.
support@ggnome.com
https://ggnome.com/wiki/documentation/
NaderF
Posts: 17
Joined: Fri Aug 06, 2021 4:41 pm
Location: US / NYC

Hello Hopki,

Thanks for the quick response.

To give stereo a try, I used a "cardboard" phone holder running VRtourViewer per ggnome recommendation. I like that software as it works great with polygons in VR and stereo, except the controller is not reliable to act the same each time. Normal VR from single images are not that telling when dealing with spaces and objects in a small space.

The holder I used is from Empir (V10.0)e. I should receive my PICO 4 today and hopefully the issue will be resolved.

I circumvented the issue of distortion in the holder by creating a parameter "Has_VR" and setting it as true, which exposes the "Enter VR" icon and allows the two images appear side by side on a monitor. The was compiled using the cardboard.ggt, which I have not used since you suggested using normal.ggt. Perhaps that was the culprit. Using normal.ggt seems to prevent the icon for VR to appear and I have not had time to repeat the test on a monitor.

I will report on the PICO in a few days. I am hoping that it will be better than the phone holder.

The stereo effect, even with the low-end holder, is powerful. I am glad also that VRtourViewer can handle polygons in VR. Hopefully that feature persists as it is a good way to present designs to clients.

Thanks again,

Nader
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