AutoCAD Map 3D General Discussion

AutoCAD Map 3D General Discussion

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Member
MALTOM
Posts: 4
Registered: ‎11-17-2010
Message 1 of 4 (276 Views)

datum conversion not shown in WKT

276 Views, 3 Replies
06-28-2012 03:54 AM

In our company we use several datums which come in multiple variants, e.g. Pulkovo, MInna and other West African ones.

We frequently need to set up alternative datum shifts to comply with client requirements for exact positioning (Oil & Gas Industry). These are usually Molodensky or Bursa-Wolfe shifts.

I have done a fair amount of experimenting with the datum creation wizards, and within AutoCAD the shifts seem to work correctly, but I am puzzled that when one views the details of the Datum Transformation from the library, the transformation parameters are not shown as part of the WKT string. Also, presumeably consequently, when data from a drawing with a coordinate system based on this shift is exported to ESRI shapefile format, the transforamtion parametere are not shown in the .prj file.

I do not know whether I have missed a stage in the creation process, or if this this is a bug. It also seems odd that when viewing the details of a user-defined datum, there is no obvious clue as to what the transformation parameters are for that datum, other than finding a transformation with the same code name.

I should be grateful for any explanation of these points.

Member
MALTOM
Posts: 4
Registered: ‎11-17-2010
Message 2 of 4 (275 Views)

Re: datum conversion not shown in WKT

06-28-2012 03:58 AM in reply to: MALTOM

Further points:

 

This is happening in AutoCAD Map 2012

Datum shifts which are Auto-Registered from R2010 files do shown up in the WKT

Product Support
phil_borycens
Posts: 189
Registered: ‎10-25-2011
Message 3 of 4 (246 Views)

Re: datum conversion not shown in WKT

07-03-2012 05:02 PM in reply to: MALTOM

Hello,

 

Is there any chance you can post screenshots of example WKT's that function differently as you describe?

 

Also, I'm not sure if this applies, but FYI, one of our developers is working on a fix to remove the illustrated parameters:

TOWGS84_ALL_ZERO.png

 

Thanks!

Phil



Phil Borycens
Member
MALTOM
Posts: 4
Registered: ‎11-17-2010
Message 4 of 4 (239 Views)

Re: datum conversion not shown in WKT

07-04-2012 05:40 AM in reply to: phil_borycens
Hi Phil, thanks for your interest. Attached is a Word document with a selection of screen shots, also two .dwg files with the relevant projections attached. I hope this makes the problem clearer. Why should one want to remove these parameters from the WKT as they are necessary for creating the .prj for ESRI? >From Alice. Alice Thomson Cartographic Office GEMS Survey Limited A member of the GEMS International Group of Companies Geotechnical, Geophysical and Metocean Expertise around the World St James House, St James Place, Gains Lane, Devizes, Wiltshire, SN10 1FB England Company Registration Number: 3083699 T: +44 (0)1380 735200 F: +44 (0)1380 735201 alice.thomson@gems-group.com:mailto:maxine.collins> www.gems-group.comGEMS International Group fully supports environmental awareness. Please consider the environment before printing this e-mail. This e-mail and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this e-mail in error please notify the sender and delete the material from any computer.:mailto:maxine.collins>
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