Changing Coordinate Systems

[bap020799]

Does anyone know how to change a drawing from Michigan GeoRef to State Plane coordinate system? Is there an add on or coordinate calculator somewhere?

[cadtag]

I'll presume you're talking about Map3d? since vanilla ACAD has no concept of mapping coordinate systems.

If that's the case, set up a new empty drawing on the coordinate grid you want to be on, and then query in the objects from the source drawing.

[bap020799]

I am using plain ACAD, not Map3d.

[cadtag]

Then, you _have_ no coordinate system to worry about. just a cartesian gridn of x, y (& z).

Can you clarify what you mean by "Michigan GeoRef"? That does not come up in the list of defined coordinate systems (Map3d 2011) - there is a "Nad83 datum, Georef Hotine Oblique for whole state (meter)" listed -

And, which Michigan state plane system you want to be on? There are about 25 listed for that state....

[bap020799]

I downloaded a file from http://www.mcgi.state.mi.us/mgdl/?rel=ext&action=sext, and it appears it is done in the Michigan GeoRef coordinate system. I need to convert that to a different coordinate system a client uses, NAD-83 Datum, Michigan State Plane, North Zone, US Feet.

[cadtag]

Ok, going though the readme there for MapInfo suggests that it's the Hotine Oblique (Meters) being used. Can you confirm that the distances in the file you downloaded are in meters rather than feet?

If so, draw a box, using points in the drawing you can readily identiy, wblock that out, and post the drawing file here. I can convert that for you, and you should be able to insert it as a block at 0,0,0 & use it to scale and relocate the GeoRef file to match.

[bap020799]

It was in meters when I downloaded. I scaled it to feet, at 0,0. Attached is the block.

Thank you for all your help.

[cadtag]

Please create the box without scaling, doing that makes it unfeasible to query the linework into the desired coordinate system, because the scaled version is no longer on any identifiable system.

[cadtag]

Also, if you're using 2013, please save the box back to 2010 format -- corp has not upgraded.

[bap020799]

I didn't realize that would screw it up, sorry. Also, just out of curiosity, which program do you use?

Again, thanks for the help.