Convert State Plane to UTM

[mkredhage]

I have a project in Alabama. The survey was completed in State Plane Coordinates. The contractor wants to use State Plane Coordinates for staking, so I plan to do the design in State Plane Coordinates. The problem is the reviewing agency wants CAD submittals in WGS84. The surveyor has given me several points with coordinates in both systems, so I should be able to make the conversion before I issue for review.

Other than using vanilla AutoCAD scale, move, and rotate commands, does anyone have any suggestions for making the conversion easier?

Thanks!

[sinc]

Well, the problem that springs to mind is that WGS84 isn't actually a coordinate system... It's a datum. The coordinate system gets built on the datum...

Are they saying they want it in UTM-WGS84? That would actually be a coordinate system...

[mkredhage]

Yes, UTM-WGS84.

[sinc]

In theory, the conversion should be easy. But unfortunately, Autodesk has made something of a mess of things...

There is an easy way to transform things, using Map queries. Unfortunately, Map queries don't work on any C3D entities.

What exactly do you have to submit?

If you basically just need to give them dumb CAD files, then one option might be to explode all your Civil 3D elements into basic Autocad entities. Then you could create a new drawing, set the coordinate zone of the new drawing to UTM-WGS84, and use a Map query to pull everything from the "exploded" drawing into this new drawing. Everything will be transformed from State Plane to UTM as you perform the query.

[bhaugi]

Sinc has given you the best way to do it within AutoCAD. I always like to cross-check and verify when doing transformations, you could do this by checking your control points with something like Corpscon.

Please, please do not promote the "move/scale/rotate" option. If all you care about is "close enough for construction" that may work. As far as control work, datum transformation is much more complex than just move/scale/rotate.

[sinc]

Actually, if it's just for submittal to a reviewing agency, Move/Scale/Rotate might end up being the easiest thing...

I've been encountering bizarre issues with Map lately, trying to query C3D 2010 drawings. And trying to figure out why a Map query is crashing C3D can burn a lot of time...

Here's hoping that one day Autodesk will turn this into the one-button task it should be... We should be able to "Export to Coordinate System", which should ALSO be capable of applying the Transformation Tab settings, so we can do things like export a drawing in a Project (i.e. ground-based) coordinate system to State Plane for giving to the local GIS guys, etc.

[mkredhage]

We started a new file in the destination coordinate system, then exported from the original file into a landxml file, and imported the landxml file into the new drawing. It only exported the Civil 3D entities, but the rest can be copied or referenced fairly easily to match.

The coordinates provided by the surveyor (I assume they used Corpscon) provide a backcheck.

Thanks for your help.

[WScottAllenPE]

What I do is create a new drawing with metric units, and xref the other drawing into it, move the xref to the new coordinate system and rotate it as necessary. I use Corpscon to get the translation (X,Y) and rotation to north corrected between the two. The scaling should be fixed automatically if the UTM drawing is meters, and the SP drawing is feet.

This leaves me only one drawing to worry about, but the second drawing is in the proper coordinates. (I use this for aerials and USG that I download as UTM and reference in my SP drawings).