[Proj] Projection Dev - How to call other projectionsfrom aprojection?

[Clifford J Mugnier]

I got my definition/distinction from Dr. Muneendra Kumar who probably got it from Dr. Ivan I. Mueller.
 
Clifford J. Mugnier, C.P., C.M.S.
Chief of Geodesy,
Center for GeoInformatics
Department of Civil Engineering 
Patrick F. Taylor Hall 3531
LOUISIANA STATE UNIVERSITY 
Baton Rouge, LA  70803
Voice and Facsimile:  (225) 578-8536 [Academic] 
Voice and Facsimile:  (225) 578-4578 [Research] 
Cell: (225) 328-8975 [Academic & Research]
Honorary Life Member of the 
Louisiana Society of Professional Surveyors 
Fellow Emeritus of the ASPRS 
Member of the Americas Petroleum Survey Group


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From: proj-bounces at lists.maptools.org on behalf of Noel Zinn (cc)
Sent: Mon 10-Oct-11 14:21
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] Projection Dev - How to call other projectionsfrom aprojection?



>From the Geodetic Glossary, NGS, NOAA, 1986

 

"spheroid 

 

(1) Any surface differing but little from a sphere, (2) An ellipsoid of revolution, (3) A surface derived, by use of a standard formula for the Earth's potential, by giving the potential one specific value (Such a surface is intended to be an approximation to the geoid), (4) By extension, a surface close to the geoid or approximating the geoid.  

 

Although sense (2) has been widely used in geodetic literature, modern practice is to employ "ellipsoid of revolution" as a specific figure, and "spheroid" in sense (1) as a general term.  Many reference ellipsoids of older vintage have been called spheroids (e.g., Bessel spheroid) and are so listed in this glossary."

 
Noel Zinn, Principal, Hydrometronics LLC
+1-832-539-1472 (office), +1-281-221-0051 (cell)
noel.zinn at hydrometronics.com (email)
http://www.hydrometronics.com (website)

 
From: Michael P Finn <mailto:mfinn at usgs.gov>  
Sent: Monday, October 10, 2011 1:24 PM
To: PROJ.4 and general Projections Discussions <mailto:proj at lists.maptools.org>  
Cc: proj at lists.maptools.org ; proj-bounces at lists.maptools.org 
Subject: Re: [Proj] Projection Dev - How to call other projections from aprojection?
 

Interesting. 

So where is a threshold (that turns a spheroid into an ellipsoid)? Technically all spheroids are ellipsoids, mathematically. (Further, a sphere is also an ellipsoid whose semi-major and semi-minor axes are identical.) 





From: 	Charles Karney <charles.karney at sri.com> 
To: 	<proj at lists.maptools.org> 
Date: 	10/10/2011 07:34 AM 
Subject: 	Re: [Proj] Projection Dev - How to call other projections from        aprojection? 
Sent by: 	proj-bounces at lists.maptools.org	

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This may be true is cartography.  It's only partly true in geodesy --
some authors make a distinction, e.g.,

  W. A. Heiskanen and H. Moritz, Physical Geodesy,
  (Freeman, San Fransisco, 1967)

use spheroid to refer to an approximately spherical shape.  (This was,
presumably, its original meaning.)


On 10/09/11 19:43, Noel Zinn (cc) wrote:
> "Spheroid" and "ellipsoid" are synonyms for the same thing in geodesy and
> cartography.
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