Curved horizon - PTGui and Photoshop comparison

[Hannu Lehto]

I think this is the first time when Photoshop panorama was better than PTGui's. PTGui pano the horizon is curved and in PS it is straight. I wonder why.

https://hanu.fi/images/panoramas/vuosaari/ptgui.hlo.jpg
https://hanu.fi/images/panoramas/vuosaari/ps.hlo.jpg

You can download the four source images. They are all 3840px high (originals 8192px). 

https://hanu.fi/images/panoramas/vuosaari/hlo400.jpg https://hanu.fi/images/panoramas/vuosaari/hlo401.jpg https://hanu.fi/images/panoramas/vuosaari/hlo402.jpg https://hanu.fi/images/panoramas/vuosaari/hlo403.jpg

PTGui version is 12.27.
The images were developed with Lightroom and Profile Corrections was used. (Canon RF 24-240mm F4-6.3 IS USM)
With PTGui few control points in the sky was removed. No difference though.

[PTGui Support]

Hi Hannu,

It looks like you took the images handheld? There is some parallax in
the foreground.

Next time when you shoot the images, rotate around the front of the
lens. Don't rotate the camera around your body. This results in images
without parallax, and PTGui will give a straight horizon automatically.

It can be fixed in this case:

In Lens Settings, set the focal length to 35mm
Go to Optimizer and uncheck 'optimize focal length'
Run the Optimizer
In the Panorama Editor, press Center Panorama followed by Fit Panorama.

I have attached my project file.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 10/10/25 09:50, Hannu Lehto wrote:
> I think this is the first time when Photoshop panorama was better than
> PTGui's. PTGui pano the horizon is curved and in PS it is straight. I
> wonder why.
>
> https://hanu.fi/images/panoramas/vuosaari/ptgui.hlo.jpg <https://

> hanu.fi/images/panoramas/vuosaari/ptgui.hlo.jpg>
> https://hanu.fi/images/panoramas/vuosaari/ps.hlo.jpg <https://hanu.fi/
> images/panoramas/vuosaari/ps.hlo.jpg>

>
> You can download the four source images. They are all 3840px high
> (originals 8192px).
>
> https://hanu.fi/images/panoramas/vuosaari/hlo400.jpg https://hanu.fi/
> images/panoramas/vuosaari/hlo401.jpg https://hanu.fi/images/panoramas/
> vuosaari/hlo402.jpg https://hanu.fi/images/panoramas/vuosaari/hlo403.jpg

> <https://hanu.fi/images/panoramas/vuosaari/hlo400.jpg%20https://hanu.fi/
> images/panoramas/vuosaari/hlo401.jpg%20https://hanu.fi/images/panoramas/
> vuosaari/hlo402.jpg%20https://hanu.fi/images/panoramas/vuosaari/hlo403.jpg>

>
> PTGui version is 12.27.
> The images were developed with Lightroom and Profile Corrections was
> used. (Canon RF 24-240mm F4-6.3 IS USM)
> With PTGui few control points in the sky was removed. No difference though.
>

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[Hannu Lehto]

This was helpful, thx.

There is one strange thing happening. When I start from scratch and load
the four images, Lens in 2. Set up panorama is 35 mm rectilinear.
After pressing Align images, it changes to 124.7 mm rectilinear.
Probably this is because 'optimize local length' is the default?

/hannu

ps. still wondering why PS got it straight...

[PTGui Support]

Exactly, and this happens because of the parallax in your images.

PTGui can no longer correctly estimate the focal length due to parallax.
The curved horizon is caused by the error in focal length.

If you shoot without parallax, it should work fine with "optimize focal
length" enabled.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

[John Houghton]

Hannu, For handheld panoramas, remove control points on near features that are very likely to suffer from parallax issues, and when checking, remember to check not only image overlaps 1-2, 2-3... but also 1-3, 2-4....  After doing this for your project, I found that the focal length parameter came out at 37.3mm when that was included in the optimization. 

John

[Hannu Lehto]

Good tip.
In some cases I have deleted all control points from image pairs 1-3, 1-4, 2-4,2-5 and so on.
In this case the panorama is better measured by the numbers. In the images the difference is usuallly very small.
/hannu

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[tonesh]

It's more than 12 years I'm using this method with a 35mm
Just don't put your finger on the focus ring.
Exact NPP point is +/- 1 cm.
It's possible to do multirow either.