[Proj] PROJ4 7 parameter datum shift Beijing 1954

Geoff Shipton geoff at tritonimaginginc.com
Mon Mar 28 13:44:52 EST 2011

Greetings to all,


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


We have a customer in Shanghai China that is uses something he refers to as
the Shanghai Local projection.


It is built on Beijing 1954 and uses that datum, the 7 parameter shift he
gives are as follows:


TX:          170.076

TY:          154.924

TZ:          97.308

RX:         1.666408

RY:          0.872624

RZ:          -8.648183

K:            0.00000186


The Ellipsoid is Krassovsky 1940


The local coordinate system parameters are TM:


CM: 121.46716061

Scale: 1.0

False Eastings: 0

False Northings: -34587140.589


I constructed the following PROJ4 string:


+proj=tmerc +lat_0=0 +lon_0=121.46716061 +k=1 +x_0=0 +y_0=-3457140.589
+towgs84=170.0760,154.9240,97.3080,1.6664,0.8726,-8.6482,0.00000186 +units=m


However I am not getting the correct results, for example.

WGS84 coordinate

31° 17' 27.50965" N          121° 35' 54.41138" E        13.7729

Should give Shanghai Local coordinate

12501.0727E       6164.1228N


However the position from PROJ4 is:

12953.30E            6042.97N


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.


Geoff Shipton,
Triton Imaging Inc.
Customer Support.
Capitola CA.
geoff at tritonimaginginc.com

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.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.maptools.org/pipermail/proj/attachments/20110328/250de912/attachment.htm 

More information about the Proj mailing list