Problem linking to CAD file

[Anonymous]

I am working in a Revit model where a CAD survey was imported several times into numerous views. It was also linked into at least one view but was not visible in all plans. Over the course of a long time and numerous users touching it, some of the imported symbols have been moved in various directions and they are not consistent from one view to another.

To combat this I have gone through every view and removed all of the import symbols and removed the linked file. I have audited, purged and flattened the CAD file and am trying to link it into the Revit model again so that there is only one file being used as the survey reference. The problem is that something is now happening to the file when it comes into Revit. The lines are askew and I can't snap to any of the CAD linework which is making it impossible to align the CAD file to the linework in my Revit file. None of the previous CAD files behaved this way. In CAD the survey file appears to be fine. Any thoughts as to what's happening here?

[ToanDN · Accepted solution]

The CAD file may have elements too far apart so that it covers more than 20 miles when linked in Revit. Open the CAD file and ZOOM Extent to verify (with all layers ON).

By the way, why would you flatten the survey CAD file? Shouldn't it be with the correct Z values so that you could create a topo in Revit?

[constantin.stroescu]

I'll add to all that ToanDN very well suggests, to uncheck: Correct Lines that are slightly off axis when inserting the CAD file.

[Anonymous]

Thanks Toan - I had checked zoom extents and they don't extend beyond the boundaries of the visible drawing (all layers are on and unfrozen as well).
Re: flattening the file - I just wanted to make sure there weren't hidden lines that were causing problems, just one of those things you try when desperately trying to troubleshoot compatibility issues across platforms.

[Anonymous]

Thanks! I have tried it both with 'Correct Lines' checked and unchecked, but the same results.

[ToanDN]

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@Anonymous wrote:
Thanks Toan - I had checked zoom extents and they don't extend beyond the boundaries of the visible drawing (all layers are on and unfrozen as well).
Re: flattening the file - I just wanted to make sure there weren't hidden lines that were causing problems, just one of those things you try when desperately trying to troubleshoot compatibility issues across platforms.

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But how big is the visible drawing?  Measure from one corner to another other and see how long it is.

[Anonymous]

Approx. 300m from one corner to the other

[barthbradley]

I don't see a difference, other than background color.  

Want to post the dwg? 

[Corsten.Au]

Hi..

try to take a print, ( PDF ) etc. and if prints are showing correct CAD etc then you may just

ignore the jittery lines showing on the screens..

There are number of things affecting that which needs to be fixed before it shows up correctly.. 

for example

1. Different Autocad file version compared to Revit version..

2. AutoCAD elements with Blocks.. ( sometimes exploding the blocks in CAD helps to get 

clean lines.. but on the other hand, exploding may result in loss of data)

3. Scale, units mis match...

list is actually endless and any one of those can affect the graphics..

if time permits, then search the actual problem..

otherwise

1. Have a Reference lines in CAD

2. Match those in Revit to locate it correctly 

3. Test the output in Export, PDF, PRINTs.. 

if this works then just ignore the problem which exists only on computer screen... 

best of luck

[Anonymous]

Thanks ganesh – I appreciate your thoroughness. My problem is persistent and it is becoming pressing. I’ll try to respond to each item in order so as not to leave any stone unturned:

• PDF print attached; All lines print normally
• The issue is more than hatch lines appearing jittery on the screen. The building extents and property lines are askew which means I can’t use this survey as an accurate underlay for our site plan approval.
• Our office AutoCAD and Revit were both upgraded to 2019 in May 2018
• I tried exploding everything in the CAD file but the problem persists
• The problem persists regardless of whether the units are matched between the two files
• I have tried drawing a reference line in the CAD file to align to the same point in the Revit file but I can’t snap to any lines or endpoints when the CAD file is linked. When I try to find a snap on a line from the linked CAD file, I see a ‘ghost’ blue dashed line that is slightly off axis from the line I’m trying to snap to (see attached jpegs).

I’ve attached a version of the CAD plan here for reference. I’m getting a bit desperate so if anyone has any clue how to fix this I’d appreciate it.

[Corsten.Au · Accepted solution]

Hi

CAD elements, move to WCS 0,0,0,

thats the original CAD elements and WCS centre... so far away..

I have sent a private message with the screencast link...

it works pretty smoothly..

cheers

[Anonymous]

Thank you Ganesh!!! I am so grateful! I guess this is also related to Toan's suggestion that the file extents were too large, but I didn't think to check the origin point. Thanks everyone for helping out!