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I haven't used CAD in years and am quite rusty about its features. But a client who uses CAD has been experiencing difficulty lining up *dwg files exported from ArcGIS in their CAD workspace. How can I export tha data in GIS so that it is referenced to fit their workspace? Or how can they make adjustments to fit the data themselves?


Sorry I got caught up working on other projects. Thank you for the response guys. The client is not using Map 3D so projections are not important as I understand it from my CAD days.

The problem is when the shapefile is exported in ArcGIS to *.dwg the client is asking for a reference point. According to Brad's instructionsI have another question. Does that mean we should agree on a point in the shapefile as a reference point that they have as well in their CAD data, and I then send them the coordinates for it to use to make adjustments in CAD? Does CAD even use geodetic coordinates?

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Can you please expand the problem? as in are you using projections? (CAD Doesn't understand projections) –  dassouki Jun 21 '11 at 17:41
1  
@dassouki Map 3D AutoCAD Products do understand projections but agree @Claude could expand on the question. –  Mapperz Jun 21 '11 at 20:41

2 Answers 2

  1. if they are drawing in just autocad, you will be relegated (restricted) to planar equal area coordinate systems as the output.
  2. if they are drawing using autocad map3d then there is at least a chance that the drawing is in an actual crs to start with.

if 1 then you wil need to move, rotate, scale the dwg using a known point as "base point".
I ussually do them in the order listed unless the scale is WAY out. you should hope not because that means you are changeing from something other than a similar measure unit. you need a line connecting two known points in the data.

find a point that you know the coordinates for and also has a position in the dwg.
Use that as base point.
Turn on /thaw and unlock all layers.
move all (command) m(enter) all(enter)
select known point as base.
type in the coordinate of the known point.

zoom extent

If you don't need to scale first to be able to detect the angle you need to rotate. go to the rotate command. ro(enter)
select the SAME base point. (read the command line carefully).
p(for previous selection)
r(for reference)
select the same base point
select a point in the data that you have the second set of coordinates for.
now type the second set of coordinates.
(doesn't matter if they are scaled correctly you have both data in the correct angle now.)

On to the third step. scaling. You are using empirical scaling. you take the distance of something and give it the correct distance.
So type the command scale(enter)
type p(for previous) (enter) select the SAME base point
r(for reference) (enter)
select the base point again
now select the second known point
now type @x,y (where x is the horizontal coordinate and y is the vertical) (with an @ symbol in front is absolute location)
If all went well you should be done...
Oh i'm sure you just did that on a copy of original

If 2 just set the coordinate system in map and export to shp.

If I mistype or missed a step I aplogize. that was all from memory
let me know if there are problems

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In case you want to do the work for your client, I propose a different approach (and longer): - export the shapefile in the client's coordinate system by georeferencing (it should work flawlessly.

For that, you will need a dwg from the client with data that you can georeference well so that you work in the client's coordinate system.

How do you do this ? You georeference your data over the client's dwg. In ArcGIS of course.

To georeference your data over the client's data, your data needs to be in dwg format and the client's data needs to be in ArcGIS format (shapefile for example).

  1. You export your data into mydata.dwg
  2. You import the client's dwg data (into client.shp).
  3. Open ArcMap, georeference mydata.dwg over client.shp (optional you could save the georeferencing points into a text or wld)
  4. Export the georeferenced mydata.dwg as you want and than give it to the client.

All this is based on the assumption that you can find common points (as distant as you can) between your data and the client's data.

Hope it works !

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