<HTML dir=ltr><HEAD><TITLE>Re: [Proj] How to transform between NAD83 HARN/HPGN and WGS84</TITLE>
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<DIV dir=ltr><FONT face="Times New Roman" color=#000000 size=2>The analogies are incomprehensible as offered. CorpsCon performs State Plane and UTM transformations to better than a tenth of a millimeter round-trip accuracy. The datum transformations are kosher NGS NADCON in that they use the original NGS data files. There is no better tool available other than <U>re-computing an entire original traverse on another datum using the new endpoint coordinates.</U></FONT></DIV>
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<DIV dir=ltr><FONT size=2>NADCON is the official method to transform among the U.S. North American Datums as published in the <EM>Federal Register</EM>. CorpsCon was written by the U.S. Army Topographic Engineering Center and uses the original NADCON data files as developed by Cdr. Warren Dewhust of the U.S. National Geodetic Survey. TEC used NGS 5 as the authoritative source for the equations for the State Plane Coordinate Systems as also declared and published in the <EM>Federal Register</EM>.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>Whether transforming gopher holes or tiepoints for a nuclear reactor, there is no better transformation package available.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>C. Mugnier</FONT></DIV>
<DIV dir=ltr><FONT size=2>LSU</FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> proj-bounces@lists.maptools.org on behalf of Landon Blake<BR><B>Sent:</B> Thu 19-Feb-09 13:22<BR><B>To:</B> PROJ.4 and general Projections Discussions<BR><B>Subject:</B> Re: [Proj] How to transform between NAD83 HARN/HPGN and WGS84<BR></FONT><BR></DIV>
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<P><FONT size=2>I'd be careful using something like Corpscon for data that is sub-foot<BR>accuracy and needs to stay that way.<BR><BR>We wouldn't use that program or any like it to convert data that needs<BR>to be that accurate. I don't know what the purpose of Aaron's data<BR>conversion is, but he might need to be careful.<BR><BR>Transforming the location of gopher holes using Corpscon is one thing.<BR>Transforming building corner positions, or the alignment of a new<BR>pipeline with Corpscon is another thing entirely.<BR><BR>Landon<BR>Office Phone Number: (209) 946-0268<BR>Cell Phone Number: (209) 992-0658<BR><BR><BR><BR>-----Original Message-----<BR>From: proj-bounces@lists.maptools.org<BR>[<A href="mailto:proj-bounces@lists.maptools.org">mailto:proj-bounces@lists.maptools.org</A>] On Behalf Of Richard Greenwood<BR>Sent: Thursday, February 19, 2009 10:42 AM<BR>To: PROJ.4 and general Projections Discussions<BR>Subject: Re: [Proj] How to transform between NAD83 HARN/HPGN and WGS84<BR><BR>Corpscon (<A href="http://crunch.tec.army.mil/software/corpscon/corpscon.html">http://crunch.tec.army.mil/software/corpscon/corpscon.html</A>)<BR>based on NADCON is a good, free, authoritative tool when working in<BR>the US.<BR><BR>Regards,<BR>Rich<BR><BR>On Thu, Feb 19, 2009 at 10:20 AM, Aaron Friesen <aaron@cartopac.com><BR>wrote:<BR>> Everyone,<BR>><BR>> I checked the archives for the past year and did not find an<BR>> answer to this. Google did not provide me with any leads<BR>> either.<BR>><BR>> I have data in NAD83 HARN for Colorado. I need to take the<BR>> data into the field as WGS84, update it/add to it, and get<BR>> it back as NAD83 HARN for Colorado. The data I am collecting<BR>> has sub-foot accuracy, so "close" is not good enough.<BR>><BR>> The information on the grid files does not address the<BR>> HARN/HPGN question.<BR>><BR>> Is this type of transformation with the accuracy I need<BR>> possible with Proj?<BR>><BR>> Are HARN grid files available or are towgs84 settings defined<BR>> for the various HARN areas?<BR>><BR>> Or am I stuck looking for an alternative, commercial solution?<BR>><BR>> Thank for your assistance.<BR>><BR>> Aaron<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>><BR><BR><BR><BR>--<BR>Richard Greenwood<BR>richard.greenwood@gmail.com<BR>www.greenwoodmap.com<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><BR><BR>Warning:<BR>Information provided via electronic media is not guaranteed against defects including translation and transmission errors. If the reader is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this information in error, please notify the sender immediately.<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>