No subject
Mon Jun 6 10:06:03 EST 2011
=E2=80=9Cspheroid=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
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.=E2=80=9D
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=20
Sent: Monday, October 10, 2011 1:24 PM
To: PROJ.4 and general Projections Discussions=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?
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=20
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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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<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>From the Geodetic =
Glossary, NGS,=20
NOAA, 1986</P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal> </P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>=E2=80=9Cspheroid =
</P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal> </P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>(1) Any surface =
differing but=20
little from a sphere, (2) An ellipsoid of revolution, (3) A surface =
derived, by=20
use of a standard formula for the Earth's potential, by giving the =
potential one=20
specific value (Such a surface is intended to be an approximation to the =
geoid),=20
(4) By extension, a surface close to the geoid or approximating the =
geoid.<SPAN=20
style=3D"mso-spacerun: yes"> </SPAN></P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal> </P>
<P style=3D"MARGIN: 0in 0in 0pt" class=3DMsoNormal>Although sense (2) =
has been=20
widely used in geodetic literature, modern practice is to employ =
"ellipsoid of=20
revolution" as a specific figure, and "spheroid" in sense (1) as a =
general=20
term.<SPAN style=3D"mso-spacerun: yes"> </SPAN>Many reference =
ellipsoids of=20
older vintage have been called spheroids (e.g., Bessel spheroid) and are =
so=20
listed in this glossary.=E2=80=9D</P>
<DIV> </DIV>
<DIV style=3D"FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: =
12pt">Noel Zinn,=20
Principal, Hydrometronics LLC<BR>+1-832-539-1472 (office), =
+1-281-221-0051=20
(cell)<BR>noel.zinn at hydrometronics.com =
(email)<BR>http://www.hydrometronics.com=20
(website)<BR></DIV>
<DIV=20
style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; =
COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: =
none">
<DIV style=3D"FONT: 10pt tahoma">
<DIV> </DIV>
<DIV style=3D"BACKGROUND: #f5f5f5">
<DIV style=3D"font-color: black"><B>From:</B> <A title=3Dmfinn at usgs.gov=20
href=3D"mailto:mfinn at usgs.gov">Michael P Finn</A> </DIV>
<DIV><B>Sent:</B> Monday, October 10, 2011 1:24 PM</DIV>
<DIV><B>To:</B> <A title=3Dproj at lists.maptools.org=20
href=3D"mailto:proj at lists.maptools.org">PROJ.4 and general Projections=20
Discussions</A> </DIV>
<DIV><B>Cc:</B> <A title=3Dproj at lists.maptools.org=20
href=3D"mailto:proj at lists.maptools.org">proj at lists.maptools.org</A> ; <A =
title=3Dproj-bounces at lists.maptools.org=20
href=3D"mailto:proj-bounces at lists.maptools.org">proj-bounces at lists.maptoo=
ls.org</A>=20
</DIV>
<DIV><B>Subject:</B> Re: [Proj] Projection Dev - How to call other =
projections=20
from aprojection?</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV=20
style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; =
COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: =
none"><BR><FONT=20
size=3D2 face=3Dsans-serif>Interesting.</FONT> <BR><BR><FONT size=3D2=20
face=3Dsans-serif>So where is a threshold (that turns a spheroid into an =
ellipsoid)? Technically all spheroids are ellipsoids, mathematically. =
(Further,=20
a sphere is also an ellipsoid whose semi-major and semi-minor axes are=20
identical.)</FONT> <BR><BR><BR><BR><BR>
<TABLE style=3D"COLOR: #000000" width=3D"100%">
<TBODY>
<TR vAlign=3Dtop>
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>From:</FONT>=20
<TD><FONT size=3D1 face=3Dsans-serif>Charles Karney=20
<charles.karney at sri.com></FONT>=20
<TR vAlign=3Dtop>
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>To:</FONT>=20
<TD><FONT size=3D1 =
face=3Dsans-serif><proj at lists.maptools.org></FONT>=20
<TR vAlign=3Dtop>
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Date:</FONT>=20
<TD><FONT size=3D1 face=3Dsans-serif>10/10/2011 07:34 AM</FONT>=20
<TR vAlign=3Dtop>
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Subject:</FONT> =
<TD><FONT size=3D1 face=3Dsans-serif>Re: [Proj] Projection Dev - How =
to call=20
other projections from =20
aprojection?</FONT>=20
<TR vAlign=3Dtop>
<TD><FONT color=3D#5f5f5f size=3D1 face=3Dsans-serif>Sent by:</FONT> =
<TD><FONT size=3D1=20
=
face=3Dsans-serif>proj-bounces at lists.maptools.org</FONT></TD></TR></TBODY=
></TABLE><BR>
<HR noShade>
<BR><BR><BR><TT><FONT size=3D2>This may be true is cartography. =
It's only=20
partly true in geodesy --<BR>some authors make a distinction,=20
e.g.,<BR><BR> W. A. Heiskanen and H. Moritz, Physical =
Geodesy,<BR> =20
(Freeman, San Fransisco, 1967)<BR><BR>use spheroid to refer to an =
approximately=20
spherical shape. (This was,<BR>presumably, its original=20
meaning.)<BR><BR><BR>On 10/09/11 19:43, Noel Zinn (cc) wrote:<BR>> =
"Spheroid"=20
and "ellipsoid" are synonyms for the same thing in geodesy and<BR>>=20
cartography.<BR>_______________________________________________<BR>Proj =
mailing=20
list<BR>Proj at lists.maptools.org<BR></FONT></TT><A=20
href=3D"http://lists.maptools.org/mailman/listinfo/proj"><TT><FONT=20
size=3D2>http://lists.maptools.org/mailman/listinfo/proj</FONT></TT></A><=
TT><FONT=20
size=3D2><BR></FONT></TT><BR><BR>
<P>
<HR>
_______________________________________________<BR>Proj mailing=20
list<BR>Proj at lists.maptools.org<BR>http://lists.maptools.org/mailman/list=
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