Linking AutoCAD drawing as background

[lbeyer593018]

I am having problems linking a DWG file into a revit model, to show a background site plan behind the structural plan. I can link the file correctly, and position it where I want it in the view (the civil drawing is located at point (500,500) in the AutoCAD coordinate system, and with a different orientation), but when I close the file and re-open it, the linked cad is no longer in the correct place.

I get an error message that says "Imported objects located a large distance from the model might not display properly. The 'Center-to-Center' option will be used". This causes the linked file to move from the location I initially placed it in and pinned it.

This is what the file looks like when I first link it. The extents box is only around the actual items.
Actual DWG.png

Then, once I've synched the file, closed, and opened it again, the extents box has become huge.

Giant DWG.png

The actual linework in the drawing is too small to see, and my revit elements are in the opposite corner.

I've already modeled and detailed the structural items, and there are several different structures that are all correctly located in relation to each other. I would like to be able to show the CAD backgrounds and locate everything on the same plan, and be able to have it update when changes are made on the civil side.

Has anyone else run into this problem? Is there a workaround or am I just stuck?

[mwiggins]

In CAD move the site to be near 0,0,0. Save it then link it in. HTH

[lbeyer593018]

That does work, but the idea is to be able to link the drawing that the civil side of the office is working on, so that when they make changes everything is automatically updated. The surveyor starts way out at 500 or whatever, and the civil drawings are all based off the survey. It seems to be kind of random what works and what doesn't, I have the existing conditions plan working fine but the civil plan is still broken (they are drawn to the same coordinates, so I'm not sure what is causing the difference.)

[DaveP]

500,500 what?
Inches, feet, miles?
You are supposed to be able to link in something as long as it's less than 20 mile across. (2 miles pre-2012)
So you should be able to see that.
If that doesn't work, one other trick some people have had luck with is to XREF your Site plan into a blank DWG with the graphics near the origin, and then link THAT drawing into Revit.

[jeffh]

The first video in this series shows how to import an Civil DWG file into Revit and then relocate the Survey point in Revit to match the DWG coordinates. Using this method should allow your Civil enginerr to work where ever they like and still keep it coordinated with the Revit project.

http://usa.autodesk.com/adsk/servlet...12&id=13734321

[lbeyer593018]

I don't really know - they're using a coordinate system set up for the entire campus. It shouldn't be more than 20 miles though. And I can see it - it just doesn't stay where I want it to.

The xref trick might work, but it would be sort of a pain. I talked to one of our civil guys, and he said that everything was referenced to a common coordinate system, and the existing conditions plan was xrefed to a layer. Deleting that layer seemed to help, at least as far as shrinking my extents box down. We'll see though - reloading might mess it up again.

[gbrowne]

Is there a possibility of some rogue information on the original CAD drawing? What if you copy the info you require and paste it to original coords in a new, clean CAD file, and link that in?

[lbeyer593018]

I think I figured it out - they were using a campus wide coordinate system, and xrefing existing conditions. There was a dummy layer used for setting the xrefs to the correct coordinate system. Once I deleted the xref layer from the linked CAD file it stopped getting giant. I guess it was reading the zero point as drawing data. It still gives me the center to center warning, but it doesn't actually move the CAD files in relation to the revit model elements, so I don't care. And whenever the civil guys change stuff it shows up in my model, which was the goal all along.