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Mon Jun 6 10:06:03 EST 2011

```=20

"spheroid=20

=20

(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. =20

=20

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."

=20
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)

=20
From: Michael P Finn <mailto:mfinn at usgs.gov> =20
Sent: Monday, October 10, 2011 1:24 PM
To: PROJ.4 and general Projections Discussions =
<mailto:proj at lists.maptools.org> =20
Cc: proj at lists.maptools.org ; proj-bounces at lists.maptools.org=20
Subject: Re: [Proj] Projection Dev - How to call other projections from =
aprojection?
=20

Interesting.=20

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.)=20

From: 	Charles Karney <charles.karney at sri.com>=20
To: 	<proj at lists.maptools.org>=20
Date: 	10/10/2011 07:34 AM=20
Subject: 	Re: [Proj] Projection Dev - How to call other projections from =
aprojection?=20
Sent by: 	proj-bounces at lists.maptools.org=09

________________________________

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.
_______________________________________________
Proj mailing list
Proj at lists.maptools.org
http://lists.maptools.org/mailman/listinfo/proj =
<http://lists.maptools.org/mailman/listinfo/proj>=20

________________________________

_______________________________________________
Proj mailing list
Proj at lists.maptools.org
http://lists.maptools.org/mailman/listinfo/proj

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<DIV dir=3Dltr><FONT color=3D#000000 size=3D2 face=3D"Times New Roman">I =
got my definition/distinction from Dr. Muneendra Kumar who probably got =
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style=3D"FONT-VARIANT: small-caps; FONT-SIZE: 10pt">Center for =
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<DIV style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal><SPAN =
style=3D"FONT-SIZE: 10pt">Department of Civil Engineering =
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<HR tabIndex=3D-1>=0A=
<FONT size=3D2 face=3DTahoma><B>From:</B> =
proj-bounces at lists.maptools.org on behalf of Noel Zinn =
(cc)<BR><B>Sent:</B> Mon 10-Oct-11 14:21<BR><B>To:</B> PROJ.4 and =
general Projections Discussions<BR><B>Subject:</B> Re: [Proj] Projection =
Dev - How to call other projectionsfrom aprojection?<BR></FONT><BR></DIV>=0A=
<DIV>=0A=
<DIV dir=3Dltr>=0A=
<DIV style=3D"FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt">=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>From the Geodetic =
Glossary, NGS, NOAA, 1986</P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>&nbsp;</P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>&#8220;spheroid </P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>&nbsp;</P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>(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.<SPAN>&nbsp; =
</SPAN></P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>&nbsp;</P>=0A=
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>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.<SPAN>&nbsp; </SPAN>Many reference =
ellipsoids of older vintage have been called spheroids (e.g., Bessel =
spheroid) and are so listed in this glossary.&#8221;</P>=0A=
<DIV>&nbsp;</DIV>=0A=
<DIV style=3D"FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: =
12pt">Noel Zinn, Principal, Hydrometronics LLC<BR>+1-832-539-1472 =
(office), +1-281-221-0051 (cell)<BR>noel.zinn at hydrometronics.com =
(email)<BR>http://www.hydrometronics.com (website)<BR></DIV>=0A=
<DIV style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: =
'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; =
TEXT-DECORATION: none">=0A=
<DIV style=3D"FONT: 10pt tahoma">=0A=
<DIV>&nbsp;</DIV>=0A=
<DIV style=3D"BACKGROUND: #f5f5f5">=0A=
<DIV><B>From:</B> <A title=3Dmfinn at usgs.gov =
href=3D"mailto:mfinn at usgs.gov">Michael P Finn</A> </DIV>=0A=
<DIV><B>Sent:</B> Monday, October 10, 2011 1:24 PM</DIV>=0A=
<DIV><B>To:</B> <A title=3Dproj at lists.maptools.org =
href=3D"mailto:proj at lists.maptools.org">PROJ.4 and general Projections =
Discussions</A> </DIV>=0A=
<DIV><B>Cc:</B> <A title=3Dproj at lists.maptools.org =
href=3D"mailto:proj at lists.maptools.org">proj at lists.maptools.org</A> ; <A =
title=3Dproj-bounces at lists.maptools.org =
href=3D"mailto:proj-bounces at lists.maptools.org">proj-bounces at lists.maptoo=
ls.org</A> </DIV>=0A=
<DIV><B>Subject:</B> Re: [Proj] Projection Dev - How to call other =
projections from aprojection?</DIV></DIV></DIV>=0A=
<DIV>&nbsp;</DIV></DIV>=0A=
<DIV style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: =
'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; =
TEXT-DECORATION: none"><BR><FONT size=3D2 =
face=3Dsans-serif>Interesting.</FONT> <BR><BR><FONT size=3D2 =
face=3Dsans-serif>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.)</FONT> <BR><BR><BR><BR><BR>=0A=
<TABLE style=3D"COLOR: #000000" width=3D"100%">=0A=
<TBODY>=0A=
<TR vAlign=3Dtop>=0A=
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>From:</FONT> =0A=
<TD><FONT size=3D1 face=3Dsans-serif>Charles Karney =
&lt;charles.karney at sri.com&gt;</FONT> =0A=
<TR vAlign=3Dtop>=0A=
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>To:</FONT> =0A=
<TD><FONT size=3D1 =
face=3Dsans-serif>&lt;proj at lists.maptools.org&gt;</FONT> =0A=
<TR vAlign=3Dtop>=0A=
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Date:</FONT> =0A=
<TD><FONT size=3D1 face=3Dsans-serif>10/10/2011 07:34 AM</FONT> =0A=
<TR vAlign=3Dtop>=0A=
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Subject:</FONT> =0A=
<TD><FONT size=3D1 face=3Dsans-serif>Re: [Proj] Projection Dev - How to =
call other projections from&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
aprojection?</FONT> =0A=
<TR vAlign=3Dtop>=0A=
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Sent by:</FONT> =0A=
<TD><FONT size=3D1 =
face=3Dsans-serif>proj-bounces at lists.maptools.org</FONT></TD></TR></TBODY=
></TABLE><BR>=0A=
<BR><BR><BR><TT><FONT size=3D2>This may be true is cartography.&nbsp; =
It's only partly true in geodesy --<BR>some authors make a distinction, =
e.g.,<BR><BR>&nbsp; W. A. Heiskanen and H. Moritz, Physical =
Geodesy,<BR>&nbsp; (Freeman, San Fransisco, 1967)<BR><BR>use spheroid to =
refer to an approximately spherical shape.&nbsp; (This =
was,<BR>presumably, its original meaning.)<BR><BR><BR>On 10/09/11 19:43, =
Noel Zinn (cc) wrote:<BR>&gt; "Spheroid" and "ellipsoid" are synonyms =
for the same thing in geodesy and<BR>&gt; =
cartography.<BR>_______________________________________________<BR>Proj =
mailing list<BR>Proj at lists.maptools.org<BR></FONT></TT><A =
href=3D"http://lists.maptools.org/mailman/listinfo/proj"><TT><FONT =
size=3D2>http://lists.maptools.org/mailman/listinfo/proj</FONT></TT></A><=
TT><FONT size=3D2><BR></FONT></TT><BR><BR>=0A=
<P>=0A=
<HR>=0A=
_______________________________________________<BR>Proj mailing =
list<BR>Proj at lists.maptools.org<BR>http://lists.maptools.org/mailman/list=
info/proj</DIV></DIV></DIV></DIV></BODY></HTML>
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