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<DIV>First thing to try is to reverse the signs of the three rotations. I
believe that proj.4 uses a “position vector” rotation sense. This may be a
“coordinate frame” transformation. Judging from the RZ value and the
differences in Eastings, this might work (but I haven’t run the numbers).
-Noel</DIV>
<DIV> </DIV>
<DIV style="FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt">Noel Zinn,
Principal, Hydrometronics LLC<BR>+1-832-539-1472 (office), +1-281-221-0051
(cell)<BR>noel.zinn@hydrometronics.com (email)<BR>http://www.hydrometronics.com
(website)<BR></DIV>
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<DIV> </DIV>
<DIV style="BACKGROUND: #f5f5f5">
<DIV style="font-color: black"><B>From:</B> <A title=geoff@tritonimaginginc.com
href="mailto:geoff@tritonimaginginc.com">Geoff Shipton</A> </DIV>
<DIV><B>Sent:</B> Monday, March 28, 2011 1:44 PM</DIV>
<DIV><B>To:</B> <A title=proj@lists.maptools.org
href="mailto:proj@lists.maptools.org">proj@lists.maptools.org</A> </DIV>
<DIV><B>Subject:</B> [Proj] PROJ4 7 parameter datum shift Beijing
1954</DIV></DIV></DIV>
<DIV> </DIV></DIV>
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<P class=MsoNormal>Greetings to all,<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>I am looking for some assistance with a problem we have using
the PROJ4 libraries, I am not a programmer neither am I geodesist – however I
know enough to be dangerous! Please bear with me…<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>We have a customer in Shanghai China that is uses something
he refers to as the Shanghai Local projection.<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>It is built on Beijing 1954 and uses that datum, the 7
parameter shift he gives are as follows:<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>TX:
170.076<o:p></o:p></P>
<P class=MsoNormal>TY:
154.924<o:p></o:p></P>
<P class=MsoNormal>TZ:
97.308<o:p></o:p></P>
<P class=MsoNormal>RX:
1.666408<o:p></o:p></P>
<P class=MsoNormal>RY:
0.872624<o:p></o:p></P>
<P class=MsoNormal>RZ:
-8.648183<o:p></o:p></P>
<P
class=MsoNormal>K:
0.00000186<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>The Ellipsoid is Krassovsky 1940<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>The local coordinate system parameters are TM:<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>CM: 121.46716061<o:p></o:p></P>
<P class=MsoNormal>Scale: 1.0<o:p></o:p></P>
<P class=MsoNormal>False Eastings: 0<o:p></o:p></P>
<P class=MsoNormal>False Northings: -34587140.589<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>I constructed the following PROJ4 string:<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>+proj=tmerc +lat_0=0 +lon_0=121.46716061 +k=1 +x_0=0
+y_0=-3457140.589 +ellps=krass
+towgs84=170.0760,154.9240,97.3080,1.6664,0.8726,-8.6482,0.00000186 +units=m
+no_defs<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>However I am not getting the correct results, for
example.<o:p></o:p></P>
<P class=MsoNormal>WGS84 coordinate<o:p></o:p></P>
<P class=MsoNormal>31° 17' 27.50965"
N 121° 35' 54.41138"
E 13.7729<o:p></o:p></P>
<P class=MsoNormal>Should give Shanghai Local coordinate<o:p></o:p></P>
<P class=MsoNormal>12501.0727E
6164.1228N<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>However the position from PROJ4 is:<o:p></o:p></P>
<P
class=MsoNormal>12953.30E
6042.97N<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>We very rarely need to invoke this type of transformation so
it’s quite possible something is awry with our code, but I sure would appreciate
any thoughts on the problem.<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P>
<P class=MsoNormal>Geoff Shipton,<BR>Triton Imaging Inc.<BR>Customer
Support.<BR>Capitola CA.<BR>geoff@tritonimaginginc.com<BR><BR>The information
contained in this message may be privileged or confidential information intended
solely for the use of the addressee(s). Any views or opinions presented in
this communication do not necessarily represent those of Triton Imaging,
Inc. If the reader of this message 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
communication in error, please immediately notify me and you are hereby
instructed to delete all electronic copies and destroy all printed
copies.<o:p></o:p></P>
<P class=MsoNormal><o:p></o:p> </P></DIV>
<P>
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