PanoTools mailing list archive

Sender:JD Smith
Date/Time:Thu, 13 May 2004 10:30:49 -0700
Subject:Re: {HTML} New tutorial - running the optimizer


On Wed, 2004-05-12 at 23:36, John Houghton wrote:
> Thanks for your comments.  I deliberately did not go into details 
> about projections because this is generally covered in beginners' 
> tutorials already.  I did consider that having a table listing their 
> straight line preservation characteristics might be helpful.  I think 
> I will probably do that.  Thanks for the interesting observation that 
> straight lines in rectilinear images are projections of great 
> circles.  This is obvious when you realise that the lines correspond 
> to the intersection of two planes, but I had not thought of it in 
> those terms.

Thanks for the comments.  For the *real* scoop on these projections (and
others) see Mathworld:

Used by PanoTools:

Rectilinear Projection (aka Gnomonic, aka Gnomic, aka Tangent Plane):

Cylindrical Projection (aka Cylindric):
Equirectangular Projection (aka Rectangular, aka Plane Chart, aka
"Unprojected", aka "PSphere" (by Helmut only?)):
Fisheye Projection (aka Azimuthal Equidistant Projection):

Other interesting projections for Panoramas or source material:

Fisheye "OP" Projection (aka Orthographic Projection):
The general class of cylindrical equidistant projections (of which
Equirectangular is one):
e.g. the Miller equidistant with phi_1=37.5 deg is said to offer the
least distortion overall.  

The cylindrical Equal area projections:

of which the Lambert variations would be interesting for prints of full
360deg panos.

I do have a bit of trouble understanding the projection names in the
libpano code.  Does anyone know what the difference between sphere_cp
and sphere_tp is, and what "mirror" is?


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