exporting to AutoCAD with a desired (0,0,0)

[umichtrojn]

I am working on a project thats part of a bigger College campus phase. all the other projects are in AutoCAD, and sharing the same civil site plan. I have imported that site plan, but due to its origin (1300+ miles out in the Pacific Ocean) it is too big to insert origin to origin. so Revit automatically inserts it center to center. is there a way to get my site plan to export correctly with the correct origin, or do i need to create a project specific origin, and document that exact point on the overall campus site plan so the consultants can orient/place their plans correctly?

I apologize if this is a re-post, but i did a quick search, and only found topics relating to true north and project north (which i have already set up).

Thank you,

[LRaiz]

If you set up your true north by acquiring coordinates from linked dwg then you should be able to use shared coordinates on export and everything will fall into place. However there are reports that having dwg origin far away from Revit project causes some problems. I suspect that extent of these problems is exaggerated and I think it is worth trying to see if things actually work well enough.

I read explanations related to problems of far away origin and they make only partial sense to me. All calculations in Revit as well as in Autocad are made with double precision which is more then sufficient even when origins are 2000 miles apart. The only place where precision may become an issue is while producing screen images with OpenGL. which internally does everything in single precision. The outcome of all this is the possibility that everything is recorded accurately in the database but there are some mistakes in hidden line removed picture. If such artifacts are observed they should be considered an indication of Revit bugs as ways definitely exist to work around OpenGL single precision limitations.

[umichtrojn]

i tried doing Steve Stafford's approach of linking in an autocad file, establishing its coordinates as the shared coordinates, and then linking in my model, and it didnt work, but i will try again.

Thanks again!

[LRaiz]

Try the procedure that I described in This thread (http://forums.augi.com/showthread.php?t=67705). You may find that it works better.

[Steve_Stafford]

Once you've acquired the coordinates system of the dwg, when you export to dwg you have to select "Shared" (found via Options button in Export dialog) in order to export according to the dwg's 0,0. If it is set to project then it won't end up in the correct location.

[umichtrojn]

Once you've acquired the coordinates system of the dwg, when you export to dwg you have to select "Shared" (found via Options button in Export dialog) in order to export according to the dwg's 0,0. If it is set to project then it won't end up in the correct location.

I have tried that. I obviously am doing something incorrect. and my frustration is growing exponentially. I have tried the 2 methods outlined below (paraphrased from Steve_Stafford's instructions as well as LRaiz's method. remember, this is a project which i modeled the topo, set the true north/project north (by rotating an AutoCAD Site plan to be the orientation i need it) and am now trying to remedy my problem.

Method 1:
1. I have my building file with the site plan (a .rvt file that was created from an imported cleaned/purged AutoCAD file). That Building file also has a couple of AutoCAD Site files linked in. These AutoCAD site files have the origin 1300+ miles away, and came in center to center, and i have moved the links to match my Revit file.
2. I go to Tools > Shared Coordinates > Acquire Coordinates, and i click on the linked drawing. I opted to save the origin.
3. When exporting (to AutoCAD 2004) I have tried having my file at True North and Project North, however both ways give me an origin in the middle of what was my Revit Building Model

Method 2:
1. I created a new file, and linked in the AutoCAD Civil Site Plan (center to Center)
2. I linked in my Revit Building Model, and rotated/moved it to place correctly on site.
3. I then clicked Tools > Shared Coordinates > Acquire Coordinates and selected my linked AutoCAD file.
4. when prompted i opted to save the origin
5. I went back into my revit Building file, and opted for shared coordinates, exported to AutoCAD 2004, made sure the shared coordinates option was selected within options.
6. upon exporting, i opened AutoCAD only to find the exported file's origin is the center-point for what would have been the Revit building model file.

Any additional help would be greatly appreciated. Thank you in advance.

[LRaiz]

I have difficulty pinpointing the problem from your description. In neither of the methods you should be prompted to save dwg. When acquiring coordinates no changes are made to the linked file and Revit should not prompt to save it. Something else must be going on. May be you can describe your process in more detail; step by step.

[sbrown]

You are just missing one step. When you export, turn off your crop region(doesn't matter if the view is set to project or true) then in the export dialog box click the options button and you'll see a box

[umichtrojn]

That is the other frustrating thing, when i turn the crop region off, the linked .rvt site plan only exports with about 10 lines. if i leave the crop region on, it exports the entire thing correctly.

i have tried just about everything suggested, and none of it seems to be working. i am obviously doing something wrong, but NOTHING i have done has gotten the exported dwg files' origins to move away from the center of the site.

[Steve_Stafford]

It sounds like there is something about the cad file that is interferring. Can you post the dwg file?