<br><font size=2 face="sans-serif">Yes, the "same thing" is a
huge confusion for many users.</font>
<br>
<br><font size=2 face="sans-serif">I am a professional cartographer but
have had a fair amount of course work in geodesy. I prefer the term ELLIPSOID
because it isn't as easily confused with a sphere as spheroid is.</font>
<br>
<br>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">"Noel Zinn \(cc\)" <ndzinn@comcast.net></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif"><proj@lists.maptools.org></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">10/09/2011 05:46 PM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: [Proj] Projection Dev - How to call
other projections from aprojection?</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Sent by:</font>
<td><font size=1 face="sans-serif">proj-bounces@lists.maptools.org</font></table>
<br>
<hr noshade>
<br>
<br>
<br><tt><font size=2>"Spheroid" and "ellipsoid" are
synonyms for the same thing in geodesy and <br>
cartography. See:<br>
<br>
</font></tt><a href=http://en.wikipedia.org/wiki/Spheroid><tt><font size=2>http://en.wikipedia.org/wiki/Spheroid</font></tt></a><tt><font size=2><br>
<br>
Do you mean that you have an ellipsoid and a sphere, maybe a conformal
<br>
sphere intermediate between the ellipsoid and the plane?<br>
<br>
What "new" projection are you implementing? Does it have
a name or is it <br>
something you invented? Is it conformal?<br>
<br>
Noel Zinn, Principal, Hydrometronics LLC<br>
+1-832-539-1472 (office), +1-281-221-0051 (cell)<br>
noel.zinn@hydrometronics.com (email)<br>
</font></tt><a href=http://www.hydrometronics.com/><tt><font size=2>http://www.hydrometronics.com</font></tt></a><tt><font size=2>
(website)<br>
<br>
-----Original Message----- <br>
From: Michael Speth<br>
Sent: Sunday, October 09, 2011 4:06 PM<br>
To: proj@lists.maptools.org<br>
Subject: [Proj] Projection Dev - How to call other projections from <br>
aprojection?<br>
<br>
Greetings,<br>
I am working on implementing a new projection and stumped on how
to<br>
call a projection from within a projection.<br>
<br>
For example, the projection has both a spheroid and ellipsoid. The<br>
function for determine the projection of the ellipsoid (both forward and<br>
inverse) use their respective spheroid projections during calculation.<br>
Unfortunately, I'm not sure if the ENTRY function can be used because<br>
for the ellipsoid calculation, but the spheroid function is only an<br>
intermediate step int the calculation and there exists additional<br>
computations after the spheroid function is called.<br>
<br>
Consider this example:<br>
<br>
INVERSE(e_inverse);<br>
lp = INVERSE(p_inverse);<br>
lp.phi = auth_lat(...);<br>
return lp;<br>
<br>
Does this make sense? If so, is there any way of calling the inverse<br>
function for sphere within the inverse function for ellipsoid?<br>
<br>
Thank you for your help<br>
Michael Speth<br>
Landcare Research<br>
Scientific Programmer<br>
<br>
<br>
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