Topic: Plant Grid System to UTM NAD 83

[M-dub]

*I'm not sure if this is the right forum to use but here's my question.*

Back when this plant was built, they created a 'Plant Grid' system based on monuments placed throughout the plant and many, many drawings were created using this grid system.  Our new plot plan was created on the UTM NAD 83 system.

One of the projects I'm working on involves moving some information (underground piping) from old, manual drawings to the new plot plan and this is the first really big hurdle I've encountered, besides the fact that I'm no piper!  After a lot of hunting and digging, I finally figured out how to overlap the two grid systems, but am now faced with a different question.

Is there a way (possibly using different layouts) to utilize both grid systems separately?  Everything I want to add to the drawing is on the old Plant Grid and it would be a lot faster and easier if I could use that system to add this new piping.

I hope that makes sense...Let me know if I need to clarify.

Thanks a lot!
Mike

[Mark]

Sorry I'm lost......

[M-dub]

Sorry...It's kinda one of those things that you have to see to believe.

Plant Grid
UTM NAD 83 Grid

The drawing is currently set up to use the UTM coordinates.  What I want (temporarily, anyway) is to change the coordinates to the Plant Grid system.

Here, you can see where the old plant grid is referenced all over the place.  Those coordinates mean nothing in the new grid system.  I need a way to go back and forth between the two.

(Does that make a little more sense? )

[Dent Cermak]

All you need is 2 common points in both systems. You then can take the old drawings amd move and rotate them to the new system. (This is the way to go. Old project systems are a dying breed.)
The new datums can be established with GPS equipment if you have no common points. You could have GPS x,y,z, coordinates set on all of the old plant coordinate monuments and then convert the system for a small amount of money. (If you are not wrapped around the wheel for accuracy, some of the hand held units could get you working numbers.) If you require cm accuracy, there should be a survey firm nearby that can do it for you.
Either way, once established, going from one system to another should be fairly easy.BUT I would convert the old plant grid and run everything on the new system from now on.

[Dinosaur]

Pretty much what Dent said . . .
If you have worked out the rotation and any scaling factors to overlay the grids, I would suggest using an xref COPY of the plant grid drawing using those factors into a copy of the drawing with the new grid system.  This copy with the new grid system will be your new master drawing.  At this point I would take the step of erasing everything from the plant grid drawing and xref the original plant grid drawing (using "overlay" option) at 0,0 insertion point to put the old linework back in.  This will prevent any of the old drawing elements being displayed in your new drawing without fussing with any layers.  You can then do all of your work on the plant grid drawing you have xref'd and all of the new linework will appear in the correct new grid position in your new drawing.  You could optionally block the new linework at 0,0 1:1 and no rotation but if you use the xref, everything is already set up should similar work need to be done in the future.

OOPS, strike that insertion info for the block option.  You need to use the same rotation and scale factor that you have discovered for the overlay to work.