Georeferencing DWG files

Question

I run ArcMap 9.1. I have some .dwg files without projections that I would overlay on aerial photos. From everything I've read, it seems that the georeferencing toolbar is the best way to accomplish this, but whenever I load the .dwg files into ArcMap, they are not recognized by the toolbar. The toolbar does work because I have used for other types of image files. Can anyone help me out with this one? Thanks.

Austin

DavidRemotti · Answer

OK, i've solved on my own. The solution is to work into a GDB with a 3 step process:
1. import from CAD into a new GDB; it creates a dataset named CADstaging
2. project the dataset; it creates another dataset name CADstaging_project (with the different prj)
3. export with the datainteroperability tool; it creates the new DWG file.

But ...
now i need to automate this process with the model builder, and i find this kind of problem: the first operation produce on output that is a GDB, while the second need a dataset as input; the same problem with the third: there is a dataset as output of the Project while i need a feature class (or feature layer) as input for the Export.
So i have a 3  step process with each step properly working, but cannot run it as a whole !
Suggestions ?
thanks in advance
David Remotti

DavidRemotti · Answer

i have done a big deal of work georeferencing some DWG files through control points on aerial photos.
Now i have two folders: one with georeferenced DWG (exported trough the interoperability tool, with some difficulties ...) and another with the original one with WLDs files. The first to be used in AutoCAD, the second in ArcMap.
Now i want to change projection for some of the "projected" DWG (let's say from UTM32 to UTM33, WGS84), and the output would be always a DWG. Is it possible in ArcGIS 9.3.1 ? How ?
I have tried the classic way using the "project" tool, but it seems not apply to DWG.
I do not want to repeat the entire control point operation and then save in a different projection ....
Thanks in advance !
David Remotti

MelitaKennedy · Answer

I run ArcMap 9.1. I have some .dwg files without projections that I would overlay on aerial photos. From everything I've read, it seems that the georeferencing toolbar is the best way to accomplish this, but whenever I load the .dwg files into ArcMap, they are not recognized by the toolbar. The toolbar does work because I have used for other types of image files. Can anyone help me out with this one? Thanks.

Austin

Austin,

In 9.1, the georeferencing toolbar didn't support CAD files yet (unless scanned images). Instead you need to identify two pairs of coordinates in the CAD's coordinate system and in the target coordinate system. You can put them into a CADname.wld file:

x1_source, y1_source, x1_target, y1_target
x2_source, y2_source, x2_target, y2_target

If you open the CAD layer's property page (in ArcMap), you can add some transformation information there instead.

There's information on this in the help. Here's the web link:

http://webhelp.esri.com/arcgisdesktop/9.1/body.cfm?tocVisable=1&ID=222&TopicName=Applying a coordinate transformation to a CAD layer

or via your installed help, ArcMap, Creating Maps, Applying a coordinate transformation...

Melita