Trying to create a 180 deg interactive image using PTGui getting curved horizontals

[Simon Anderson]

Have been trying to create a 180 degree interactive image using multiple images capture using a nodal head setup. I can successfully create the pano however when I try and output the image the horizontals are all distorted and curved. I can preview the image in PTGui using the detail viewer and the image looks great with perfectly strait verticals and horizontals. However when I output the image the horizontals alway become curved. Can anyone suggest what setting I should be using to avoid this. 

[John Houghton]

Simon, Probably the explanation for the unwanted  distortions you are seeing is to do with the projections used for a display of the images.  PTGui does its stitching on the surface of a sphere in order to encompass the view in all directions.  The Detail Viewer shows an extracted rectilinear view, in which all straight line features are preserved.  Your output of the entire 180 degree view is probably in equirectangular or cylindrical projection. See  Projections - PTGui Stitching Software for an explanation of the projections.  To get a straight horizon and perfectly upright vertical features, your panorama needs to be levelled, see Part 8 of the video tutorials on the PTGui web site (under the "Learn" heading).

John

[Simon Anderson]

Hi John 

Thanks for your advise 

I have tried this and as yet have not been able to reproduce the image the way it appears in the detail viewer. It always seems to appear with the distorted horizontal lines. Would you have any advice on the best output setting to use to get the closest possible result to how it appears in the detailed viewer. Also can you recommend an external viewer that will allow a 180 deg view, as most I have tried will try to display the image as 360 deg. eg renderstuff.

Thanks again for your assistance

Regards,

Simon

[PTGui Support]

Hi Simon,

You would need to use a panorama viewer. Displaying a full 180 degree
image while also preserving straight lines is physically impossible. The
detail viewer is such a panorama viewer: it selectively shows a smaller
part of the panorama in rectilinear projection. Only rectilinear
projection will preserve straight lines.

To keep things simple, it's best to output a full 360 x 180 degree
equirectangular image even if this means that half of the panorama will
be empty. Then in the panorama viewer, limit the viewing angle such that
the viewer will not navigate beyond the image bounds. If you use PTGui's
Publish to Website, use the min/max pan settings. See 6.15 for other
options: https://ptgui.com/faq#6_15

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 1/20/26 23:15, Simon Anderson wrote:
> Hi John
>
> Thanks for your advise
>
> I have tried this and as yet have not been able to reproduce the image
> the way it appears in the detail viewer. It always seems to appear with
> the distorted horizontal lines. Would you have any advice on the best
> output setting to use to get the closest possible result to how it
> appears in the detailed viewer. Also can you recommend an external
> viewer that will allow a 180 deg view, as most I have tried will try to
> display the image as 360 deg. eg renderstuff.
>
> Thanks again for your assistance
>
> Regards,
> Simon
>
> On Sunday, January 18, 2026 at 7:18:30 PM UTC+11 John Houghton wrote:
>
> Simon, Probably the explanation for the unwanted  distortions you
> are seeing is to do with the projections used for a display of the
> images.  PTGui does its stitching on the surface of a sphere in
> order to encompass the view in all directions.  The Detail Viewer
> shows an extracted rectilinear view, in which all straight line
> features are preserved.  Your output of the entire 180 degree view
> is probably in equirectangular or cylindrical projection. See

> Projections - PTGui Stitching Software <https://ptgui.com/man/
> projections.html> for an explanation of the projections.  To get a

> straight horizon and perfectly upright vertical features, your
> panorama needs to be levelled, see Part 8 of the video tutorials on
> the PTGui web site (under the "Learn" heading).
>
> John
>
> On Sunday, January 18, 2026 at 7:21:19 AM UTC Simon Anderson wrote:
>
> Have been trying to create a 180 degree interactive image using
> multiple images capture using a nodal head setup. I can
> successfully create the pano however when I try and output the
> image the horizontals are all distorted and curved. I can
> preview the image in PTGui using the detail viewer and the image
> looks great with perfectly strait verticals and horizontals.
> However when I output the image the horizontals alway become
> curved. Can anyone suggest what setting I should be using to
> avoid this.
>

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