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<DIV dir=ltr align=left><SPAN class=515581415-04052006><FONT face=Tahoma
color=#0000ff>I don't know about the internal workings of ArcView, but if you
use Corpscon, this is correct. Corpscon will first convert from NAD27 to
NAD83, then from NAD83 to NAD83 HARN. If you are using NAD27 State Plane
Coordinates (SPCs), this is further complicated by the fact that there was a
major shift in the NAD27 SPCs to NAD83 SPCs, then if you go to Lat-Long, there
is another conversion, and so on and so on . . .</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=515581415-04052006><FONT face=Tahoma
color=#0000ff></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=515581415-04052006><FONT face=Tahoma
color=#0000ff>I have found out (through trial and error - mostly error) that if
software is not set up to Quad Precision*, mathematical errors get into the
picture as well. Right now, I am playing around with projecting Lat-Long
to FDEP Albers using a FORTRAN program I wrote. The results using Double
Precision vs. Triple Precision* are in the centimeter range. My compiler
doesn't have Quad Precision, but I wish it did.</FONT></SPAN></DIV><!-- Converted from text/rtf format -->
<P><B><SPAN lang=en-us><FONT face="Brush Script MT" size=6>--
John</FONT></SPAN></B><SPAN lang=en-us></SPAN> </P>
<DIV><FONT face=Tahoma color=#0000ff><SPAN class=515581415-04052006>* Triple
Precision is actually 80 bit, or about 18 significant digits, utilizing the
built-in math coprocessor in the Intel chips.</SPAN></FONT></DIV><STRONG><FONT
face="Brush Script MT" size=6></FONT></STRONG><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
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<FONT face=Tahoma size=2><B>From:</B> shrug-l-bounces@lists.dep.state.fl.us
[mailto:shrug-l-bounces@lists.dep.state.fl.us] <B>On Behalf Of </B>Thomas,
Jim<BR><B>Sent:</B> Thursday, May 04, 2006 11:14 AM<BR><B>To:</B>
shrug-l@lists.dep.state.fl.us<BR><B>Subject:</B> shrug-l: NAD 83 to NAD83
HARN<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=397370415-04052006>Shruggers,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=397370415-04052006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=397370415-04052006>Is this
true?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=397370415-04052006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=397370415-04052006>"<FONT
face="Times New Roman" size=3>To project data from State Plane NAD 27 West to
NAD 83 HARN takes two (2) transformations."</FONT></SPAN></FONT></DIV>
<DIV><FONT face="Times New Roman" size=3><SPAN
class=397370415-04052006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=397370415-04052006>I'm dealing with
data referenced as FLSP-W NAD83 HARN and it's not overlaying my NAD27
data. Could it be that ArcMap is incorrectly projecting on the fly?
If I change the reference system from NAD83 HARN to NAD83, it overlays
properly. Am I missing something?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=397370415-04052006></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=397370415-04052006>Jim
T.</SPAN></FONT></DIV></BODY></HTML>