Distortions I can't get rid off

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HaraldJ
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Thu Aug 08, 2013 4:16 pm

Thanks for looking! It may be just a small issue, but I can't find it:

In this panorama, the upper edge of the walls around is not straight. Of course I would expect 3D distortions, but what I get looks more like waves in a straight line, or a long curve. It becomes mor visible if you zoom in.

Also (and perhaps part of the reason), the room seems to be wider at the bottom than it is at the top. The input image, a large TIF or JPEG, has no such issues. I tried a lot of different things, have searched the forum, now I'm asking for a bit of advice...

Any ideas would be really appreciated.

Thanks!

Harald
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Thu Aug 08, 2013 4:35 pm

Are you using a fisheye lens? Which lens?
If you are using a Sigma 8mm fisheye lens with a 180° filed of view have you remove both the lens cap ring AND the lens cap? Not removing the lens cap ring you are reducing the vertical field of view to about 160°

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HaraldJ
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Thu Aug 08, 2013 5:00 pm

Hi Dave,

Thanks for the reply. No, it wans't a fish eye, it was the Canon Canon 17-40mm, and the distortions are not in any of the original images.

The preview window ("Vieweing parameters") is absolutely fine as well, the distortions only show in the final interactive panorama.

Harald
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Thu Aug 08, 2013 5:37 pm

OK.. then input the type of panorama you are using to project is called a 'Clyinder'.

Normally INPUT dialog box by default indicates Type: AUTO. Pano2vr does its best to determine your panorama by examining your panorama dimensions. For example if your image is an equirectangle 2:1 ratio 8000 x 4000 it will choose Equirectangle.... But your panorama dimensions are probably not 2:1 like 8000 x 2500 and it then would auto-select cylinder.

IF for some reason your panorama is near a spherical 2:1 ratio like 8000 x 3895 then it might select a Equirectangle by error. In which case you should manually select cylinder. Rebuild your project and then test in a web browser.

Let us know how this works using Cylinder.
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HaraldJ
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Thu Aug 08, 2013 5:49 pm

Hi Dave,

Thanks, I'm using Cylinder, but tried the others as well. For this panorama, the original file is 22968 x 10170 pixels.

If it helps - I could put the basic file on the server to download.

Thanks!

Harald
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Thu Aug 08, 2013 6:00 pm

As a test - try using a panorama that has a width of 8000 pixels wide.

Also did you select FILE/Settings/ tab /Images\ Flash 9 "Ignore maximum image size"
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HaraldJ
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Thu Aug 08, 2013 6:09 pm

The problem seems to be specific with this panorama, there are lots of others where I can't see the issue.

The "Ignore maximum image size" switch was off, I just changed and tested it, and can't see any difference at all.
Harald Joergens
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Thu Aug 08, 2013 7:24 pm

It just might be the way you took the image:
Typically we set up on a tripod with a 360° rotator head.
The rotator head is levelled using a spirit level

All images should be the same like Canon 17-40 all @17mm
If you are using a full 35mm sensor like on a Canon 5d that would be affectively 17mm.
Otherwise that would be 17mm x 1.6 (crop factor) or effective 27mm.
Camera in Portrait orientation

Calculate the number of images around the horizon using 360° / angle of view

3rd row is same number of images tilted up +10°
1st row around on the horizon
2nd row is same number images tilted down -10°

I am thinking and guess that you might taken 27 images around the horizon. ( can count the single images stitched in the gold cornice trim at wall top)

Reading this page http://www.opyd.com/press/index.php/201 ... -panorama/ it appears you would need 32 using your lens
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HaraldJ
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Thu Aug 08, 2013 7:57 pm

Thanks Dave. I see your point, but all the stiching had been done in PTGUI, Pano2VR only knows about one big TIF or JPEG file.

If there is a different number of photos in two rows, I would expect the stitching software to stitch them together properly, so it shouldn't make any difference, and the stichted file looks perfectly okay to me, I can put it on the server for you to download if it helps,

Thanks!

Harald
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Thu Aug 08, 2013 8:13 pm

This is a good converstation. I somewhat agree. PTgui should know the number of images in order to stitch properly. However, I have tried unsuccesfully to use using our other Canon 500d (1.6 CFactor)and our Canon 10 - 22mm @10mm in portrait to manually overlap shots to get a full 360... stitching using PTgui they looked somewhat good.. few errors... until I learned that I need exactly 8 images... then stitching works. Something about the 10-22mm @10mm portrait 74° degrees angle of view on the horizon.
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jobes
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Sat Aug 10, 2013 4:11 pm

Two suggestions.

First, try a preview direct from PTGui and see if the distortions are present in that. This should help to understand if the distortion is due to the image itself, or some remapping issue in Pano2VR. I'd suspect it;'s the latter form what you've posted…

Second, make the image a 2:1 equirectangular. For this I assume you're using Photoshop, but you can do the same with other editors too.
  • Save a copy of the original file
    Make sure the main image is not a background layer, but is instead Layer 0 or similar
    Adjust the canvas size so the horizontal height is 11484
    Create a new layer and fill with a new colour… perhaps plack… it's just to test
    Save
    Use this in Pano2VR and make sure the source image is set to equirectangular
    Output the panorama and view
I'm assuming this isn't a full spherical (360x180) panorama because you didn't capture the zenith at the ceiling, or the nadir at the floor. By making the source image for P2VR an equirect you are simply adding a blank area to fill in the 'holes' at the poles where these are missing.

You can then set view limits in Pano2VR and prevent the viewer from seeing them by reducing the angle they can pan. Hope this helps
HaraldJ
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Tue Aug 20, 2013 2:24 pm

Brilliant - that solved the issue! Not only the distortions problem, but also the "converging vertical lines" when looking, for example, at a door or window.

Thank you very much!

Harald
Harald Joergens
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