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<DIV dir=ltr><FONT color=#000000 size=2 face="Times New Roman">I have always considered the identical equations to represent the Polyhedric projection (also known as the <SPAN style="FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt; mso-ansi-language: EN-US; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">Müffling projection</SPAN>). At large scales 1:100,000, 1:50,000 it seems to fit perfectly in my personal experience. My first experience with the Local Space Rectangular was in 1968 at Army Map Service for the photo-triangulation of the Apollo Lunar Landing Map series. It's a standard transformation in many photogrammetric photo-triangulation software packages. See my treatment of the Polyhedric/<SPAN style="FONT-FAMILY: 'Times New Roman','serif'; FONT-SIZE: 10pt; mso-ansi-language: EN-US; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US; mso-bidi-language: AR-SA">Müffling projection</SPAN> in the <EM>Manual of Photogrammetry</EM>, 5th edition, 2004, Chapter 3, Section 3.1.2.2, page 189. John Snyder and I did discuss that back in the 1980s, and I explained to him that this was exactly what I used to solve the infamous "Tampico Datum" problem of Mexico when I was doing some consulting work over at Offshore Navigation, Inc. back then.</FONT></DIV>
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<FONT size=2 face=Tahoma><B>From:</B> proj-bounces@lists.maptools.org on behalf of Noel Zinn (cc)<BR><B>Sent:</B> Tue 28-Jun-11 06:43<BR><B>To:</B> PROJ.4 and general Projections Discussions<BR><B>Subject:</B> [Proj] Ellipsoidal Orthographic<BR></FONT><BR></DIV>
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<P><FONT size=2>The only equations for the ellipsoidal orthographic that I've ever found<BR>published (in a book or journal) are those of Bugayevskiy and Snyder (1995),<BR>which are complicated and (the authors acknowledge) truncated. Following<BR>EPSG Guidance Note 7, Part 2, I've prepared a presentation on the<BR>ellipsoidal orthographic that offers simple, exact equations. The<BR>derivation also suggests that the ellipsoidal orthographic is unique among<BR>projections, being transitional between distorted cartography in 2D and<BR>undistorted visualization in 3D on a computer in ECEF or ENU (topocentric)<BR>coordinates. A link to the presentation follows:<BR><BR><A href="http://www.hydrometronics.com/downloads/Ellipsoidal%20Orthographic%20Projection.pdf">http://www.hydrometronics.com/downloads/Ellipsoidal%20Orthographic%20Projection.pdf</A><BR><BR>Does anyone in this group have other sources of information on the<BR>ellipsoidal orthographic?<BR><BR>Noel<BR><BR>PS - Scroll the page if it presents in black<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><A href="http://www.hydrometronics.com/">http://www.hydrometronics.com</A> (website)<BR><BR><BR>_______________________________________________<BR>Proj mailing list<BR>Proj@lists.maptools.org<BR><A href="http://lists.maptools.org/mailman/listinfo/proj">http://lists.maptools.org/mailman/listinfo/proj</A><BR></FONT></P></DIV></BODY></HTML>