Datum conversion: Clarke 1880 to WGS84

[directapproach]

I have a 2D drawing in Clarke 1880 and would like to convert the whole thing to WGS84. Would someone be able to tell me (in simple terms please) how to do that? Much thanks.

[Anonymous]

Open the dwg and assign it one of the Clarke 1880 coordinate systems. Save
and close the dwg. Open a new dwg assign it the WGS84 coordinate system. Use
the map attach tool to attach the first dwg to the new dwg (map attach not
xref) Run a location all query. detach the first dwg then save the new dwg.

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Murph
www.map3d.wordpress.com


"directapproach" wrote in message news:6232020@discussion.autodesk.com...
I have a 2D drawing in Clarke 1880 and would like to convert the whole thing
to WGS84. Would someone be able to tell me (in simple terms please) how to
do that? Much thanks.

[directapproach]

I've got it up to the point of attaching the map. What is the command or menu selection for that? Sorry to ask such basic questions, and thanks for the help.

[Anonymous]

Depends on what version and workspace you are in as to where the
menu/command is, however in the map task pane, map explorer tab, right click
on "Drawings" attach is there.

--
Murph
www.map3d.wordpress.com


"directapproach" wrote in message news:6232121@discussion.autodesk.com...
I've got it up to the point of attaching the map. What is the command or
menu selection for that? Sorry to ask such basic questions, and thanks for
the help.

[trmoji]

Hi everybody

My country Lesotho uses Lo (clarke 1880) and we would like to adopt wgs84 as we are surrounded by Republic of South Africa which uses WGS 84. So I would like to know the IMPACT THAT THIS CHANGE WOULD HAVE ON LESOTHO SURVEYS>

[bingeomatics]

trmoji, I think first you must find right datum transformation parameters form ellipsoid Clarke 1880 to ellipsoid WGS-84 for territory (matched) your country. This parameters you can find from state geodesy organization of your republic. And after it the change will be without any problems.....

[antoniovinci]

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bingeomatics wrote:

you must find right datum transformation parameters

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Well, without looking for anything, Autocad Map is brilliant in transformations (on-the-fly or not) between datums...

[bingeomatics]

Yes it is, I am agree with you, antoniovinci and I love AutoCAD Map coordinate works very much.  But user don't know which parameters use AutoCAD Map to transforms datums. And in addition, for all country must be own transform parameters. An example, I don't use default parameters to transform from Pulkovo-42 datum to WGS-84. For my country I have 7 Bursa-Wolf parameters  and I use they in AutoCAd Map (I have creat my own transform parameters in AutoCAD Map)  and using it I transform my maps. May be, directapproach, need to creat his owne parameters in AutoCAd map, too. I adviced him only it.

[antoniovinci]

I dislike using custom CRS, because they work only on your local Autocad, unless you run _ADEDEFCRDSYS everywhere (at customers too).

Another drawback of custom CRS is the export to Gis formats: Autocad will create a new .PRJ unknown to the rest of world...

[bingeomatics]

But I experimented - exported to ESRI Shape format, it works - the .prj file is normal....

[antoniovinci]

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bingeomatics wrote:

the .prj file is normal....

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What does "normal" mean for you, sir?

Did you try to open that same shapefile in a third-party Gis software?

For instance, Qgis doesn't recognize non-standard .PRJ, that's way I avoid using custom CRS...

[bingeomatics]

antoniovinci, i opened it in ArcGIS 10 and the coordinate system was recognazed. But I tried only ESRI Shape format, not oyher file formats. Perhaps it is problem of QGIS