coordinate transformation problem

[cscott.94049]

(also posted in the Autodesk map discussion group)

Hi... I am using Map/LDD 2006, and am new to using the coordinate transformation tools.

I am having difficulty transforming a file from geographic coords (nad 27 lat-long west positive) to UTM meters zone 16.

After executing the query (following the directions laid out here... Thanks guys!) I get an error that indicates that Map "Can't perform datum conversion".

The data set I am converting is large. It contains all of the MMS lease areas in the Gulf of Mexico. Obviously this area spans multiple UTM zones, but our study area is in zone 16, so I want to center the transformation there. Could my problem be that the area is too large for map to make the conversion to UTM?

Earlier this morning I was able to do an export conversion of the same data to a shape file and then import the data into the correct coord system, but now I am getting the same error using this process as well.

Should I try repairing my installation of Map/LDD? Am I missing a step?

Thanks for any help you can give me.

Cheers,
Chris

____________________
Christopher A. Scott
CAD Specialist/I.S. Administrator
Evans-Hamilton Inc.
cscott@evanshamilton.com
206.526.5622

[Glenn Pope]

Have you checked out this thread?

Combine files with different coordinate systems (http://forums.augi.com/showthread.php?t=17193&p=107733)

Following these steps do you get the error?

[cscott.94049]

Yes. This is the process I used.

Autodesk support sent me the following solution (which may or may not be the solution):

http://usa.autodesk.com/getdoc/id=TS74630

It indicates a problem converting between NAD 27 and NAD83 (or WGS84) outside of the CONUS.

Just for grins I told Map that my data was WGS84 instead of NAD 27 and tried the transformation. The error I got this time was "Can't transform point from Lat Long."

It's just a bit frustrating.

My next thought is to try and transform a subset of the data to see if I'm just trying to transform to large of an area, spanning too many UTM zones.

If anybody has time on their hands and wants to replicate my error, the data I am trying to convert (the blocks file in DXF) can be downloaded here:

http://www.gomr.mms.gov/homepg/pubinfo/repcat/arcinfo/index.html

I also have NOAA shoreline data in my map that I downloaded and scripted into polylines. That data is available here:

http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html

Cheers,
Chris

____________________
Christopher A. Scott
CAD Specialist/I.S. Administrator
Evans-Hamilton Inc.
cscott@evanshamilton.com
206.526.5622

[cscott.94049]

Hmmm... No go on the smaller subset either.

Just for a reality check I did a translation of some county data from WA state plane 83 north to UTM zone 10 meters using the same process, and that transformation worked just fine. So at least I know that I'm not doing something wrong.

I might have to find someone with ArcInfo to convert the data for me. Unless anyone has some tricks up their sleeve. ;-)

Cheers,
Chris

[mohobrien]

Are you sure the data is
geographic coords (nad 27 lat-long west positive) I just checked for the hell of it. Got the same error when I tried west positive but got it to work if I assumed regular LL27 (west negative). Centre of the blocks is 200,000 easting and 3,000,000 northing approx. Does that sound correct?

[cscott.94049]

I feel like an idiot... Yes it seems to have worked. I guess I was just suffering from rectal-cranial inversion.

However, I still got errors during the translation, and I'm not sure what points didn't translate correctly. I can get going on what I need to do though!

Thank you!

[cscott.94049]

Interesting... I tried again with the lease block data starting from scratch, and it worked without error. However my shoreline data errored out with any geometry south of about latitude 20deg.

It will still work for my purposes though, since the lease blocks are north of that latitude.

Thanks for all the help!!!

Cheers,
Chris