2 Replies Latest reply on Jul 10, 2015 12:13 PM by Califdan2

# LR Pano projections?

I'm having trouble understanding the 3 projections in LR's new Merge to Panorama.

Cylindrical:  I was able to find information on this projection method on various web sites.  My take on this projection is that it tends to maintain proper subject size across the image and is best for wide pano's but not for vertical or multi row pano's.  Does this simulate a film Panorama-swing film camera?

Spherical:  This term does not seem to be a standard word used to describe projections.  I've read that it's best for 360 degree or multi row Pano's but does anyone know what standard projection name this refers to?

Perspective:  This one too does not seem to be a standard term used to describe projections.  Is this really "Rectilinear"?  or perhaps "Equilinear"?   Or, "Flat"?  Is this a projection that preserves vertical and horizontal straight lines as straight lines at the expense of exaggerating the size of objects as you move left and right from the center?   I read that it's not good for Pano's with a field of view greater tan 120 degrees but can't seem to equate it to other information.

I want to read up more on these so I can describe them better to students but the standard definitions of projections I've found (many of which have a half dozen or more projections listed) don't use the "spherical" or "Perspective" terminology so I'm not sure which ones those terms refer to.

Thanks -- Dan

• ###### 2. Re: LR Pano projections?

HI Rick,

Yea I already read that document but am looking for a more full and scientific explanation.  For example for "spherical" it is not clear what "Aligns and transforms the images as if they were mapped to the inside of a sphere"  really means since the "inside of a sphere" is not a flat surface.  So if I imagine a slide projector at the center of a sphere that is projecting my image on the inner surface of the sphere and I imagine that surface were photographic print paper, then what?  I now conceptually have a piece of a sphere with an image on it that must in some way become a 2 dimensional flat surface and the definition on the Adobe link is silent as to how that is done (which is the same problem map makers have and which has resulted in a several different methods or "projections".   So which standard projection does Adobe's "spherical" projection represent is not evident.