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Sorry to ask, but I just don't have time for help menus this week. That said, does anyone know if CAD is capable of re-projecting shapefiles? I find myself in a situation whereby I may have to use spatial data without access to ESRI software. The data are delivered in the GCS_North_American_1983 datum, and my clients site drawing is in NAD83 Z17N.

I fully expect problems. Can any of you post any related links that you're aware of? There's no budget to purchase software on this one either (just a heads-up).

Alternatively, is there a way to get CAD to project on the fly?

Thanks in advance

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3 Answers 3

up vote 5 down vote accepted

Yes

(if you have time to watch the video)

"Show me how to bring in data and reproject it" (video at the bottom)

http://docs.autodesk.com/MAP/2010/ENU/AutoCAD%20Map%203D%202010%20User%20Documentation/HTML%20Help/index.html?url=WS73099cc142f48755156818d10b290e6faa-7fe1.htm,topicNumber=d0e206720

video link http://docs.autodesk.com/MAP/2010/ENU/AutoCAD%20Map%203D%202010%20User%20Documentation/HTML%20Help/coord_sys_set.htm

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Thank you sir. I don't have time to watch at the moment, but at a glance, I can see that the bottm link will fix my problem. Funny .... I took a CAD/GIS integration course through ESRI and they never pointed this out!! They were in fact, not aware of any way to do this. Is this a recent development? I took the course 3 yrs ago. –  Dano Apr 26 '11 at 18:41
    
@ mapperz -- just out of simple curiousity .... how well does CAD handle the assignment of multiple datums (in your experience)? Does this cause a lot of crashes etc? The reason I ask is that I've experienced similar problems when trying to add large spatial datasets to a CAD drawing. It just doesn't seem to hanldle larger spatial files all that well. This will be my first time doing this. –  Dano Apr 26 '11 at 18:49
    
@Dano -- map 3d has always been in civil 3d. That is where it gets its' capability to re-project. Not sure what you mean by multiple datums. Map does do on-the-fly re-projection and handle multiple data with multiple projections or datums. If that is what you mean - I have never seen any issue with this. Large datasets can be a problem. Because of the software architecturet you can find both a logical and a physical limitation to opening/loading data or drawings. –  Brad Nesom Apr 26 '11 at 19:02
    
Try to work with CAD in it's native format or for 3D is own database schema - reprojecting non-native (.shp) is more likely to crash than .dwg or.dxf –  Mapperz Apr 26 '11 at 19:02
1  
@ Brad -- I'm self-taught in CAD, and I don't have a mentor to lean on either (you kind folks have "basically" become my mentors!!). As I said, I took a CAD / GIS course through ESRI Canada, and I asked this very question. They told me I needed to reproject everything to the same datum/zone (in ArcCatalog) or CAD would not know what to do with it. Any time I've "not" had everything in the same datum/zone, it has not opened in the proper location. I have also just recently moved from basic CAD to the Civil software. Needless to say, I'm on the learning curve right now. –  Dano Apr 26 '11 at 19:10

I would suggest reprojecting the .shp file using ogr2ogr. In this way you can avoid any problems with Autodesk's reprojection engine crashing.

ogr2ogr -f "ESRI Shapefile" original.shp wgs84.shp -s_srs EPSG:27700 -t_srs EPSG:4326

where in this case we are re-projecting 'original.shp' from OSGB36 British National Grid to Longitude / Lattitude WGS84 and called 'wgs84.shp'.

The sofware is free so budget shouldn't be a problem here.

You can also try some of the software mentioned on this page to then convert .shp to dxf

http://software.geocomm.com/translators/cad-dxf/

references http://www.mercatorgeosystems.com/blog/?p=1 http://www.gdal.org/ogr2ogr.html

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Regular "Vanilla" Autocad doesn't have the GIS import/export functionality that Map 3D and civil 3D have. So that's perhaps why ESRI said it couldn't work. But Map 3d is excellent at converting projections, etc. I'd also suggest GlobalMapper as a cost-effective data conversion tool. You can re-project data easily and quickly using GM too.

-monkey5672

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