Moving CAD file from which coordinates were acquired

[patricks]

We are working on a project which has a survey CAD file with property lines. When I first linked in the CAD file, I rotated it and got it in position as needed in my site plan view, and then used Acquire Coordinates to get the correct True North orientation and everything.

Now today while working, I noticed the cad file had shifted wayyyy up and to the left of our site. It was fine before lunch this morning. The only thing I can think of was that I had the CAD file open and I changed the text of one of the property line bearings, and then saved the file. Perhaps this made the file shift in Revit for some reason, I don't know.

So I moved the linked CAD file back into position on my Revit site plan, and it threw up messages about shared files moving or some such thing, and that I had to open Manage Links and use Save Locations to fix it. So I did that.

Now everyone working in the file is getting messages about saving or not saving linked files or shared coordinates or something when they STC. Of course I told everyone they need to Save. Is this something that only happens once for everybody after a linked shared CAD file is moved? Did I even go through the correct process of correcting the shifted file?

[sbrown]

I had one job that did this constantly. The dwg has an origin far away from the geometry and it just gets confused or something. I found NO solution and couldn't reliably get the problem to reproduce for adsk.

[patricks]

I just checked the origin location in the CAD file... OUCH!! It's over THIRTY MILES away from the origin point 0,0,0!!!

[Andre Carvalho]

I just checked the origin location in the CAD file... OUCH!! It's over THIRTY MILES away from the origin point 0,0,0!!!

Patrick,

Try adding something like a cross in the CAD 0,0,0 in a layer that you can turn off. Usually I have less problems when I do that. Looks like Revit likes to see something drawn close to the CAD origin...

Andre Carvalho

[patricks]

It seems to be working okay now, and it was working okay before it shifted.

Is it possible the shift happened just because I edited one text object in the CAD file?

If I put a cross at 0,0,0 in the CAD file, which is 30+ miles from the survey info, wouldn't that cause problems in Revit since that cross would be more than 2 miles from Revit's origin?

[Andre Carvalho]

If I put a cross at 0,0,0 in the CAD file, which is 30+ miles from the survey info, wouldn't that cause problems in Revit since that cross would be more than 2 miles from Revit's origin?

I never had problems. I import the CAD file center to center, locate it as I want and later acquire coordinates. I also turn the layer where my cross is and crop the region to be closer to the actual drawing.

Steve Stafford also mentioned something about using a line located in the CAD's 0,0 in this post:

http://forums.augi.com/showthread.php?t=85864

Andre Carvalho

[David Conant]

I would recommend against the strategy of putting some object at 0,0 in the dwg file, particularly if that point is more than 2 miles from where your model will be constructed. This will cause the model extents of your project to extend out to the dwg's origin and can trigger a number of undesirable performance and behavior problems.

[Andre Carvalho]

I would recommend against the strategy of putting some object at 0,0 in the dwg file, particularly if that point is more than 2 miles from where your model will be constructed. This will cause the model extents of your project to extend out to the dwg's origin and can trigger a number of undesirable performance and behavior problems.

Thanks for letting us know David.

I never measured, but then probably I never had problems because my CAD files weren't more than 2 miles away from the origin? I'll try to locate the files and check it... And the funny thing is that when I had problems, adding the lines to the origin seemed to fix the issue... :roll:

Andre Carvalho

[patricks]

I would rather move the information in the CAD file over to the origin, but I don't want to deal with the CAD file moving in the Revit file again.

[Steve_Stafford]

I would recommend against the strategy of putting some object at 0,0 in the dwg file, particularly if that point is more than 2 miles from where your model will be constructed. This will cause the model extents of your project to extend out to the dwg's origin and can trigger a number of undesirable performance and behavior problems.Understood...but I find that Acquire Coordinates does not actually do it unless there is a line that goes back to the real origin. I'll have to test it again...

[Andre Carvalho]

Understood...but I find that Acquire Coordinates does not actually do it unless there is a line that goes back to the real origin. I'll have to test it again...

This is what I thought too. I have been doing this technique for a while and always worked. I still do it in Revit 2009 but have to tell you that I haven't tried without the line at 0,0 in this version to see if it works. Maybe it changed in 2009?

Andre Carvalho

[patricks]

Perhaps I should just move the survey info 30+ miles to the origin, remove the link in Revit, and then re-link the file? Would that be a possibility?

[Andre Carvalho]

Patrick,

Another option if you don't want to mess with the dwg original position (sometimes you link a file that people are still working and adding information to it) is to create a blank dwg file, Xref the original dwg and move to the origin. Then link this file to your Revit project. If someone changes the original file the changes will be reflected to your Cad file and therefore will be reflected to Revit. And you don't need to use their origin...

Andre Carvalho

[gbrowne]

Thats an excellent idea! I wish I had thought of that..

[patricks]

Yeah that is a good idea.

However this is just a survey CAD file from an engineer we received probably 2 months ago for some old buildings. Nothing done since then.