Cylindrical projection - to the interior of a cylinder

[Abrimaal]

In the cylindrical projection, the panorama is projected on the external surface of a cylinder. It is usable for objects viewed from distance (like Earth from a satellite).
I have many panoramas where the camera is "the centre of the universe".
In the example everybody can see that the objects in the middle are larger, because the panorama is projected onto a cylindrical surface.
The tree at the very left is a part of the tree at the right.

I don't want to use any of fisheye projections, because they distort the vertical lines.
Is it possible to project the panorama onto the internal surface of a cylinder?
Is this the same as rectilinear projection?
Certainly not, because rectilinear fails when the field of view is wider than 180° in this case it is 360&deg.
The average distance of objects is the same everywhere.
Some viewers can detect it and display as an equidistant looped long rectangle.
Can I save the panorama in Hugin as the rectangle, without the distortions of projections used in cartography (objects viewed from distance)?

[Abrimaal]

The internal and external surface of a cylinder.

[Erik Krause]

Am 14.05.2017 um 19:38 schrieb Abrimaal:
> In the cylindrical projection, the panorama is projected on the external
> surface of a cylinder. It is usable for objects viewed from distance (like
> Earth from a satellite).
> I have many panoramas where the camera is "the centre of the universe".
> In the example everybody can see that the objects in the middle are larger,
> because the panorama is projected onto a cylindrical surface.

May be I misunderstand. However, a panorama usually is taken from a
single viewpoint. In cylindrical projection it is projected on the
inside of a cylinder, not on the outside. Try the following: shoot a
panorama from the center of a round room or simply place same sized
objects around the camera in equal distance. The wall of the room will
unroll to an equally wide stripe, the objects will all be the same size.

> Can I save the panorama in Hugin as the rectangle, without the distortions
> of projections used in cartography (objects viewed from distance)?

Any projection has distortions. In rectilinear projection f.e. balls in
the corners are distorted to ellipses while all lines remain straight. A
fisheye will map the balls as circles but all lines not going through
the image center will be bent. There is nothing like an undistorted
projection.

More on projections see:
http://wiki.panotools.org/Projections
http://www.panotools.org/dersch/perspective/Wide_Angle_Perspective.html

--
Erik Krause
http://www.erik-krause.de

[Abrimaal]

Yes, my mistake. I was thinking about "equidistant" correction of the cylindrical view.
This is obvious that the further objects, especially these at the ends will be smaller.
Panini projection can make them larger, but generally it is sufficient for interiors and street views.
it can be compared to a projection into the interior of an elliptical surface.
I think, without manual work in a photo editor, it is impossible to make the objects close to the camera smaller, and these far larger.
But what editor... the perspective correction in graphic editors is limited to distortions of a rectangle.

[Gunter Königsmann]

Nightly builds of the gimp can transform a mesh. Still waiting for a release of that tool, though...

--
A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ
---
You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hugin-ptx+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/hugin-ptx/5aed348a-3cb7-4b10-8a87-db81515b97af%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Battle]

The key is cylinder projection vs cylindrical projection which is of a sphere on a cylinder.  ImageMagick can perform cylinder corrections on images.  This isn't exactly what you are looking for, but may be of some use when combined with other partial solutions.  

http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=18864&start=45
Battle