seam in stitching

[Gerry VPP]

Sorry if this is a duplicate but I couldn't locate any previous discussion on this. I'm having seams appear in roughly 80% of panos stitched from .nef directly into PTGui. I've used default settings on blending 'zero overlap' and changed it to 'multiband' to see if it helps, but it occurs on both blending settings. Any suggestions to remove the seam. Thanks.

[PTGui Support]

Hi Gerry,

The image you sent me shows a vertical line which seems to be at the
-180 / +180 degree boundary, where the left and right hand side of the
equirectangular image meet. This is typically caused by post processing;
the image straight from PTGui would not show the problem.

See 4.7:
https://ptgui.com/support.html#4_7

If this is not the case, I'd be happy to look into this. Just make your
source images and your project file available for download (dropbox,
wetransfer, google drive or something similar).

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[alcan...@gmail.com]

Hi,

I'm having a similar problem. There is a subtle yet visible seam in the sky. I tried offsetting the panorama in Photoshop and in the problem area I used content aware fill, but again when making viewable 360º output the seam is there. As noted, It's subtle and I've seen worse in the past and commented then, but those issues seem corrected now. I'm using the .tif output from PTGui without any further processing in Photoshop (except for the troubleshooting step of offsetting the image).

I'm using six shots - 4 horizontal, 1 up and 1 down from viewpoint optimization. 11mm on 8-15mm Nikon Zoom Fisheye

I was getting good results until the most recent update. That may reflect a change in the software or is just coincidental and the current issue is notwithstanding the version.

Please advise any further troubleshooting steps,

Lawrence 

[John Houghton]

Lawrence,  The key to correcting this problem is being able to reproduce it.  Please make available for download a sample set of images and project file that generates an output that demonstrates this fault.  Good quality jpeg images preferred unless tiff is essential.  Use wetransfer.com (free), or Dropbox or similar service and post the link here.

John

[alcan...@gmail.com]

Hi John,

I thought I had 'fixed' the problem. Using the Photoshop Offset filter I could see that that seam error was in the stitched output image. I had six fisheye images, so I went back and masked the upper third of each of the four horizontal views to exclude a good portion of the sky, knowing the zenith shot had plenty of sky for coverage. And for the zenith shot I masked around the horizon. These masks solved the problem of the unwanted seam, which was probably the whiter sky near the horizon mismatching with the blue sky and causing the whiteish vertical 'seam' up in the sky area.

However, I now see a 'dimple' at the very zenith of the sky. Only this time I don't see the cause in the stitched output image. Also, the dimple does not show in the Preview feature of PTGui, so it seems to be an artifact of the Publish to Website tool(?)

There are several variables at play here and I wouldn't know which version of the project and files to upload to Dropbox at this point. 

[John Houghton]

On Tuesday, June 20, 2023 at 2:11:24 AM UTC+1 alcan...@gmail.com wrote:

I thought I had 'fixed' the problem. Using the Photoshop Offset filter I could see that that seam error was in the stitched output image. I had six fisheye images, 

    . . . . . .  

There are several variables at play here and I wouldn't know which version of the project and files to upload to Dropbox at this point. 

It would be good if you could supply the six image files and project file that generate the output equirectangular image with the seam error.  JPG files would be fine if the fault is readily visible using them.

John

 

[alcan...@gmail.com]

Hi John,

I 'fixed' the problem (again, hopefully). This time it was a matter of masking, not what I expected, but I won't argue with apparent success. Nonetheless, I've uploaded the project files and JPG image files.

One project includes 'seam' in the filename. I also included two more: one has 'artifact' and the other has 'clean' in the filename. The appearance of a seam in the sky was the original issue. I then tried masking the center of the sky (image #5) with green and although the seam went away, an artifact in the sky near the horizon appeared along the border between the 1st and 4th rotational positions. Adding red masking to the remaining portion of the sky (image #5) eliminated the artifact and gave a clean sky.

If you have any advice moving forward I look forward to that... Perhaps I did just what is required after all.

Dropbox: https://www.dropbox.com/scl/fo/vb9wr0vvvcij52qtsjfu0/h?dl=0&rlkey=kstd0r0lz0zqtqxa5l0uvmkjf

Notes: I was using the Nikon fisheye at 11mm. I shot 4 horizontal images at 90º increments, one up shot and one shot down and off to the side (for later inclusion using Viewpoint Optimization).

Lawrence

[John Houghton]

Lawrence, Thanks for the images.  The brightness and colour of the sky varies enormously in the shots,  presumably due to the sun setting.  This creates difficulties for the blender.  I got the best results blending manually by tweaking the individual Exposure Offset parameters, while observing the results in the unblended view of the Panorama Editor.  Also I used the Multiband blending option and turned off the optimum seams option.  Project file is attached.

John

[alcan...@gmail.com]

Hi John,

Thank you. In fact, I had thought to change the blending from zero overlap to multiband, but I simply could not find where to do this. And that's because I couldn't find the blending side bar.. fortunately, because you made it clear this feature is there (somewhere), I remembered there was this right-hand pop-out menu I had never used and of course, there it is. I appreciate your detailed response because I now have multiple options for resolving these kinds of blending challenges, like a sunset sky. 
 

Lawrence

[PTGui Support]

Hi Lawrence,

Slightly decreasing the size of the cropping circle might also help (see
the Crop tab).

There's a very strong light falloff at the edge of the fisheye circle.
The Zero Overlap blender only uses the pixels at the seam, so it will
attempt to match the colors at the 'bad' outer edge of the image,
causing banding in your panorama.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

> https://www.dropbox.com/scl/fo/vb9wr0vvvcij52qtsjfu0/h?dl=0&rlkey=kstd0r0lz0zqtqxa5l0uvmkjf <https://www.dropbox.com/scl/fo/vb9wr0vvvcij52qtsjfu0/h?dl=0&rlkey=kstd0r0lz0zqtqxa5l0uvmkjf>

>
> Notes: I was using the Nikon fisheye at 11mm. I shot 4
> horizontal images at 90º increments, one up shot and one shot
> down and off to the side (for later inclusion using Viewpoint
> Optimization).
>
> Lawrence
> On Monday, June 19, 2023 at 10:25:24 PM UTC-7 John Houghton wrote:
>
> On Tuesday, June 20, 2023 at 2:11:24 AM UTC+1
> alcan...@gmail.com wrote:
>
>
> I thought I had 'fixed' the problem. Using the Photoshop
> Offset filter I could see that that seam error was in
> the stitched output image. I had six fisheye images,
>
>     . . . . . .
>
> There are several variables at play here and I wouldn't
> know which version of the project and files to upload to
> Dropbox at this point.
>
>
> It would be good if you could supply the six image files and
> project file that generate the output equirectangular image
> with the seam error.  JPG files would be fine if the fault
> is readily visible using them.
>
> John
>

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[alcan...@gmail.com]

Hi Joost,

I had started to try reducing the cropping circle as you suggest, wondering the same thing. I don't remember if it helped because I was testing a variety of mitigation strategies, but on the basis of your response, I see the importance of tightening it up a bit anyways, notwithstanding the specific issues in this particular project. The information you've shared about the Zero Overlap blender is especially good to know.

Thanks,

Lawrence