I just counted the number of projections available in PtAssembler and came up with 25. Some of those 25 are probably just there just to say that it's there and are not actually useful. Plus, there are probably a bunch that are so close to each other that in the real world it doesn't matter which one you use.

So let's say that there are ~10 usefully different projections. a) which ones are they? b) in what circumstances is one clearly better to use?


The PTAssembler link below explains a lot about those projections. It specifically answers the question you asked ... Why use the different projects?


Actually, as you'll see, PTAssembler has those variations so that you can get the control you want. Think of it as, what a DSLR is to a Point-and-Shoot.

Max Lyons added many of those variants when he wrote some of his code to replace some of Dersch's PanoTools. I use the Squeezed and Compressed Rectilinear variants for good effect.


B. Shaw

  • D'oh! How did I miss that???
    – JenSCDC
    Jul 15 '14 at 12:26
  • Andy - Don't feel bad, I think I may have originally found that page by 'googling' projections and PTAssembler.
    – B Shaw
    Jul 15 '14 at 21:10

Which projections are useful to you depends a lot on what type of panoramas you're making, the image itself, and how you want to present the pano. That list is pretty standard for any Panorama Tools-based GUI (that's where the PT in PTGui, PTAssembler, PTLens, etc. comes from).

I'd say take a spin through this Hugin manual page on projections to get a visual sense of what each of them does. It's typically about emphasizing or de-emphasizing areas of the resulting panorama, because of the distortion that's required to map the larger angles of view or a spherical field to a flat plane.

As a 360°x180° panorama shooter, my needs are probably quite different from yours, but I tend to use equirectangular as the final stitching format, because it can encompass a spherical view (as cylindrical cannot), and stereographic for little planet remapping.

  • Inkista - Actually, PTAssempler has grown in the past couple of years. It is no longer merely a front end to Dersch's PanoTools. Max Lyons wrote his own code which added a significant amount of projections.
    – B Shaw
    Jul 15 '14 at 5:11
  • Cool. I'm not that familiar with PTAssembler--just knew that I'd seen a lot of the same projections in the other PT-whatever tools. There was a lot that Dersch kept proprietary, and I do get mixed up about which codebase is from where. :)
    – inkista
    Jul 15 '14 at 18:52

No panorama projection is usefull unless you need it.

So my question is, What do you need the panorama for?

I use some panoramas as:

1) Just interesting pictures.

  • Spherical
  • Planar (Spherical Probe)
  • Cylindrical
  • Little planet

2) Viewing an interior scene or landscape on a web aplication, or desktop aplication, virtual tours.

  • Spherical
  • Cubical. 6 independent images.

3) Environmental maps in 3D rendering aplications.

  • Spherical
  • Hemispherical
  • Cylindrical
  • Planar (Spherical Probe)
  • Cubical
  • Vertical Cross, Horizontal cross.

Here is a paper I wrote some time ago as an explanation to a 3D modeling comunity, to understand a little more about the projections.


I don't use some projections like mercator. In my opinion this are used to see the exterior projection of a sphere. A panorama is the view from the inside. The projections can be the same but the aplications probably don't.

And there other projections that I don't use as panoramas like rectilinear projection, but as normal photos.

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