Fixing unstable cad drawings when inserted into Revit

[Mark_Engwirda]

I'm encountering several problems with the CAD files I'm receiving:

1. Surveyors: The origin point of their CAD files is set 10 km away from the actual site.
2. Ecologists: Their CAD files have drawing extents greater than 30 km.
3. Xrefs: They are using external references (xrefs) but not supplying the necessary files.

When I load these CAD files into programs like Revit, they become very unstable. The instability manifests as a wobbling effect when zooming in or out, and Revit also displays multiple warning dialogs about the files.

Unfortunately the people who send those files say its not their problem so I need to fix this myself, easiest way was not to engage them in the first place.

I haven't used Autocad since Autocad2.5 so its kind of changed to the extent that its now totally foreign to me.
Could someone show a step by step way of fixing the origin and extents issues in a Autocad for dummy's explanation.
 

Many thanks in advance.

Mark

[paullimapa]

First of all since they're not supplying the Xrefs, you don't have the complete drawing. You're missing perhaps very important information which may prevent you from fulfilling your scope of work.

Next, if you cannot retrieve these Xrefs, then you might as well detach them from all the dwgs you did receive.

Then, in AutoCAD instead of opening the files with the Open command use the Recover command. This would fix any corruptions in the dwg file before running the Qsave command.

While you still have the dwg opened, you might as well set the current Layer to 0 and run the Purge command to remove any unused data. You should run Purge multiple times to successfully clean up the dwg.

Lastly, I'm assuming when you're in Revit, you're Linking the dwgs and not Importing them in.  You don't want to introduce unnecessary information from these dwgs into your Revit project.

[Mark_Engwirda]

@paullimapa Thank you for the advice, unfortunately after following those steps the issue still persisted. 
I am aware that if the xrefs are missing, usually they are only a missing image in my case and not something that is important to the drawings.

Once again thank you for your help.
Mark

[pkolarik]

I'm thinking the issues you're experiencing with the surveyor's files actually is on your end. We routinely bring in the surveyor's topo file to our revit model. Yes, we'll get the warning about a point being X distance away, but that's all we get. I've not seen any adverse graphical effects of this condition in our revit models. We just ignore the warning messages.

[paullimapa]

Worse case plot the dwg to pdf at a particular scale to a paper size where you can see all the objects. Then attach the pdf into Revit and scale it back up. Now see if you still encounter the same issues

[pendean]

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@Mark_Engwirda wrote:

...Could someone show a step by step way of fixing the origin and extents issues in a Autocad for dummy's explanation.

---

1) Open one of those DWG files in AutoCAD, WBLOCK out all the content you wish to use from modelspace to create a new file.

2) Open each copy, run AECTOACAD command to create a dumbed-down DWG file for REVIT. Open this newer copy and compare with the source. Anything visually missing? If yes, ask the file create to "export to autocad" a DWG file to send you instead and have them validate the content.

3) Do with the last DWG file as you wish in REVIT.

HTH

[Mark_Engwirda]

Thats what I have been resorting to, but it feels very low tech with such high tech software.
Thanks for the suggestion.

[paullimapa]

Only way to use that hide/show feature. Or you just place the block onto a layer and then turn that layer off/on

[Mark_Engwirda]

@pendean thanks for this solution, after sleeping on it I remembered the wblock solution as a possible work around.
So I have used step one eg created a wblock of what I need and yes that is a good solution.

So what I have found is that not all of the objects are unstable within the cad file when imported in revit, just the linework and hatching from one of the xref files.  

Originally, revit advised of the screenshot warning when I imported the cad file.

When I used the wblock solution this particular warning no longer occurred, instead it came up with a warning that it needed to truncate the wblock file, which still had instability issues.

I will note the instability does not occur in Autocad itself, only when we try to import the cad file into Revit.

I hope that all makes sense?

Once again, thanks for all of your help.
Regards, Mark

 

[Mark_Engwirda]

@pkolarik  thanks for letting me know. Are you importing topo files or cad files?

This only occurs from a particular surveyor when importing their cad files, its not something that happens very often but its annoying when it does.
This might be a question to ask on the Revit forum 

Thanks, Mark

[pendean]

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@Mark_Engwirda wrote:

....I hope that all makes sense?

Once again, thanks for all of your help.
Regards, Mark

 

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You have a REVIT problem now: go ask your fellow REVIT users for help and guidance, start here

https://forums.autodesk.com/t5/revit-products/ct-p/2003 

[vitorbortoncello]

Check these links:

https://help.autodesk.com/view/RVTLT/2024/ENU/?guid=GUID-D30C39FF-3A53-47DE-8E9E-11B2AB808A07

https://help.autodesk.com/view/RVTLT/2024/ENU/?guid=GUID-3F79BF5A-F051-49F3-951E-D3E86F51BECC

Maybe it's the distance from the internal origin:

When geometry is far away from the model's internal origin, the graphical representation of elements becomes less reliable and less accurate. These issues relate to how Revit LT interprets the modeling work plane as a flat surface. In reality, the Earth's surface is curved. The farther you move away from the internal origin, the greater the likelihood of anomalies in the way that Revit displays the geometry.

  

All geometry in a Revit model should be within 10 miles or 16 kilometers of the model's internal origin.In particular, check for stray geometry in the Z direction. For an AutoCAD file, consider flattening the file to reduce the limits in the Z direction.

Consider hiding your site references (Project Base Point & Survey Point)