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<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007>John -</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007>If you have an ArcEditor license, I would do a Spatial
Adjustment if you know where the CAD file should fall on the ground and have
good reference points.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007>I don't even bother with projections for the CAD
surveys we get, just the Spatial Adjustment tools.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007>The tools may be available at the ArcMap level, I'm not
sure.</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2><SPAN
class=578422718-19072007>Tim</SPAN></FONT></DIV><BR>
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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>Sykes,
John<BR><B>Sent:</B> Thursday, July 19, 2007 2:26 PM<BR><B>To:</B>
shrug-L@lists.dep.state.fl.us<BR><B>Subject:</B> shrug-l: Surveyors,
AARRGGHH!!!<BR></FONT><BR></DIV>
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<P><FONT face=Tahoma>I just received an AutoCAD file of a survey produced in the
late 1980's. Additional field work was done in 2004 and this revised
survey is the CAD file I have.</FONT></P>
<P><FONT face=Tahoma>I assumed the survey work was done in State Plane
Coordinates NAD83, but when I created a projection file for this survey it ended
up about 30 miles west of the site when I let the file project on the
fly!</FONT></P>
<P><FONT face=Tahoma>So I went back and created a new projection file, this time
establishing the coordinates as State Plane Coordinates (SPC) NAD27. When
I imported the CAD drawing I immediately saw that the CAD drawing was coming out
southwest of where it should be by about 50 ft. I realized that the
surveyor apparently had taken a SPC NAD27 file and offset it by the correction
factor from NAD27 to NAD83 without taking into account the difference in the
offset that also exists between the two projections (I have been told that this
30 mile offset was added to the SPCs to make if obvious when the wrong
projection was being used).</FONT></P>
<P><FONT face=Tahoma>The problem is that, if I reproject the SPC NAD27 file to
SPC NAD83, it adds the offset between the two datums back in again!!!
Short of getting the surveyor to correct their file (not likely since the job
was finished in 2004) how do I get this error corrected???</FONT></P>
<P><FONT face=Tahoma>By the way, I tried telling the PRJ file that the
coordinates were SPC NAD27 and the datum was NAD83, but that didn't work.
Also, I found that the reprojection tool in the toolbox doesn't work for CAD
files.</FONT></P>
<P><FONT face=Tahoma>Of course, ultimately I'm trying to get this whole thing
into FDEP Albers for my map.</FONT> </P>
<P><B><FONT face="Brush Script MT" size=6>-- John</FONT></B> </P></BODY></HTML>