Visible Vertical Line

Q&A about the latest versions
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Sebastian
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Sat Jan 22, 2011 2:05 pm

Hi there guy

I wanted to re-export my older projects to provide clients with the new, neat transitions between panoramas, but I noticed there is a visible vertical line once I export the project. The line wasn't there before and I haven't modify or touch these images at all, since the last time I worked on it. I use 6000x3000 tif. By the way, the old Panorama online, does not have the line.

Never mind that, I export the image to Cube Face, retouch the line, then turn it back into Equirectangular image. The image became 5997x2998, it lost 1 pixel and the line is gone.
Whatever project I convert from one format to another, I keep loosing pixels.
Anyone experience that?

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regards
Sebastian
smooth
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Sat Jan 22, 2011 2:22 pm

Typically you get the vertical line if the import panorama image has not been flattened.

Same when resizing in Photoshop or sharpening. You must flatten the layers first.

As for losing a pixel with Pano2VR when go from one format to another I also notice this. I guess it is using a pixel for overlap.
Thomas might like to explain this? but that is my take on things.

Regards, Smooth 8)
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Hopki
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Sun Jan 23, 2011 10:49 am

Hi Smooth
Hope you well, I will pop this in the bug tracker as this should not be happening.

On a different subject,
As someone who I conceder to be, on top of their game, I have a question regarding Fisheye lens.
If the larger the F stop and the longer the exposure gives better depth of field, why is it then the Sigma Fisheye 8mm is at its optimum at F8?

Just thought I would ask, :)
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smooth
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Sun Jan 23, 2011 1:33 pm

Hopki wrote: If the larger the F stop and the longer the exposure gives better depth of field, why is it then the Sigma Fisheye 8mm is at its optimum at F8?
Optimum at f/8.0? That is not necessarily so. But one could argue that it is the sweet spot for panorama shooting.
Any lens with a short (in this case very short) focal length has great depth of field and are pretty much in focus right across the range.
The Sigma 8mm Fisheye generally performs best between f/5.6 and f/9.0 taking in factors of DOF, Exposure, Lens Flare and Vignetting.
Of course to get the absolute maximum from it requires you to focus the lens at the Hyperfocal distance.

It is worth mentioning that because as panorama photographers we are shooting all angles (complete 360) with one single f/stop, shutter speed etc that we are attempting to get both shadows and highlights in range in one attempt. This as you know can be up to 2 to 4 f/stops from one side to the other. Say bright sun to under brush shadows.
Should you shoot at the same shutter speed say at f/22 you will knock the highlights down but plunge the darker areas into total blackness. Similarly at the opposite end f/3.5 shadows will be fine but you will blow out on all the highlights into mass white losing cloud detail or even the majority of the "blue"? sky ending up with a white bloom. On the short fixed focal range of the Sigma 8mm Fisheye the DOF is not greatly affected from one end to the other.

Better people than me have written articles and Theseus' on the subject. A quick search for "Fisheye DOF" on Google should find all the information you could possibly ever want to know and then some.

Regards, Smooth 8)
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erik leeman
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Sun Jan 23, 2011 2:25 pm

It's not an exposure 'thing' as such, it's an optical issue.
With the aperture wide open (the largest aperture opening = the smallest F-stop number) you'll see all optical flaws of a lens in their full glory in your images.
Close that aperture to its smallest size of a particular lens (= the largest F-stop number) and an unwanted quality of light itself, named 'diffraction' will spoil them instead.

So making the aperture small enough to get rid of most of the lens flaws, but not so small to trade them in for diffraction blur is what you do if you want the best possible image quality from any lens.
From that 'sweet spot' you then compromise if needed to get a deeper DoF, or the opposite, a shallower one, by making the aperture smaller or larger resp.

An 8mm/F2.8 fisheye probably has that sweetspot around F5.6 or maybe even a bit lower than that, generally the 'longer' the lens the higher the optimum F-stop number is.

Erik
Last edited by erik leeman on Sun Jan 23, 2011 6:14 pm, edited 1 time in total.
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360Texas
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Sun Jan 23, 2011 6:05 pm

Original thread talks about a noticable vertical line.
A spherical image must be an exact 2:1 ratio dimensioned image. An image hight that is 1/2 the width. Examples: 4000 wide x 2000 high pixels.
IF you see a thin black line it means probably that your image is NOT a 2:1 ratio... or say 3999 x 2300 dimensions.

Mathmatically:
To determine a cube size you would divide the stitched image width by Pi or 3.1415 like 6000 pixel width / 3.1415 = 1909.9 or 1910 x 1910 pixel square.
When converting cube faces back to equirectangular panorama
1909.9 x 3.1415 = 5999.9999 [produces visible single line] not quite the original 6000 pixels.

Using the value of 4 works alittle better
6000 / 4 = 1500
1500 x 4 = 6000

Pano2vr version 2.3.4
You can find a setting [FILE SETTINGS] called REMAPPING 'Use width.pi as conversion factor' and OUTPUT 'use width/pi as output factor
Default setting is [x] Use width/pi as conversion factor

Pano2vr version 3.0 has same setting location and default setting.

I am only guessing here but I think that deselecting divide by Pi causes pano2vr to use divide by 4 option.

If you use the default setting "/pi" option you need to be sure that you change your conversion width from 3999 to even number 4000 or what ever your original with was.
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erik leeman
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Sun Jan 23, 2011 6:18 pm

The original question was already answered Dave, simply flattening the equirect usually removes the black seam.

Erik
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360Texas
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Sun Jan 23, 2011 7:12 pm

In Photoshop I can open a NON 2:1 ratio size panorama image.. add layers .. flatten.. save as jpeg / Tif. and the line will appear. Sometimes the converting 2:1 ratio image into cube faces.. then converting back at 1 pixel off will cause the single vertical pixel line.

Flattening multilayer image background +1 layer panorama alone will not fix the issue.
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Hopki
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Sun Jan 23, 2011 9:07 pm

Hi Chaps
Thanks for your input, just thought I would ask.
I have add this to the bug tracker Issue #169 so it will be looked at by Thomas.
Once again many thanks.
Hopki
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Sebastian
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Mon Jan 24, 2011 1:16 am

360Texas wrote:Original thread talks about a noticable vertical line.
A spherical image must be an exact 2:1 ratio dimensioned image. An image hight that is 1/2 the width. Examples: 4000 wide x 2000 high pixels.
IF you see a thin black line it means probably that your image is NOT a 2:1 ratio... or say 3999 x 2300 dimensions.
Hi there Texas :)
The images are 6000x3000. I did check them in Photoshop multiple times. See, the very same image worked without any problem for the past 2 years. It was just the recent new version that output the file with an additional line.
360Texas wrote: ....
Pano2vr version 2.3.4
You can find a setting [FILE SETTINGS] called REMAPPING 'Use width.pi as conversion factor' and OUTPUT 'use width/pi as output factor
Default setting is [x] Use width/pi as conversion factor
Pano2vr version 3.0 has same setting location and default setting.
I am only guessing here but I think that deselecting divide by Pi causes pano2vr to use divide by 4 option.
If you use the default setting "/pi" option you need to be sure that you change your conversion width from 3999 to even number 4000 or what ever your original with was.
Thanks for pointing that out. I have been using Pano2VR for 3 years, and never even noticed that settings :)

Thank you Texas and the rest of you guys, for taking the time to look up my post.
Last edited by Sebastian on Mon Jan 24, 2011 1:56 am, edited 1 time in total.
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360Texas
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Mon Jan 24, 2011 1:37 am

You are welcome. We try to help other forum folks.
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