imported AutoCAD files

[malcolm.swan]

I'm having trouble with imported AutoCAD files in Revit. I've imported an AutoCAd plan to use as an underlay for tracing my building pad in the site plan. The imported lines, particularily arcs, are not displayed clearly, despite regenerating the lines and having them display perfectly in the AutoCAD file before importing. A line drawn as an arc in AutoCAD appears as a squiggled line composed of multiple line segments and vertices. Is there a setting that can correct this appearence or any technique to use while importing to prevent this? Thanks

[patrick.murphy77679]

Amazingly....bumping this subject, as it troubles me today. Any solutions out there?

[Duncan Lithgow]

I can't say what is causing your problem, but I have two observation. Sometimes going with a more detailed view scale helps with oddly behaving DWG files. But my real question is why did you import it? Normally it's a much much better idea to link your DWG file. By importing it you've created a whole kingdom of line styles and new geometric points in space which can be difficult to clean up later.

[jsteinhauer]

Agreed!!!

But my real question is why did you import it? Normally it's a much much better idea to link your DWG file. By importing it you've created a whole kingdom of line styles and new geometric points in space which can be difficult to clean up later.

Link your CAD files in and use native Revit objects to rebuild, plans or details. Once done, remove CAD ASAP.
Cheers,
Jeff S.

[damon.sidel]

If you are using the ACAD as an underlay as the original poster was, all you really need is the radius of the arc, right? In ACAD, you could start by drawing a line for the radius starting at the arc center point and then delete the arc. In Revit, you'd then have all the necessary information to draw whatever arcing geometry you need and the actual ACAD arc representation wouldn't get in the way. Then as Jeff says, remove the CAD, ASAP. :)

[DaveP]

As to the OP, if the lines are not making smooth arcs, my guess would be that it is far from the origin.
It a known issue with ACAD that the farther you get from the origin, the more rounding errors occur.
Especially since he mentioned a site plan, I'd bet the DWG is a few thousand feet out there.
If that's the problem, select everything in the DWG and move it closer to 0,0

[MikeJarosz]

With Revit, location in space matters. Real thought should be given to locating the building accurately, which means mastering shared coordinates. Too many Acad drawings were plunked down wherever the crosshairs were. Unless the building is located correctly in Revit, analyses like shadow and energy studies will be wrong.

CAD systems store items like arcs and lines a number of different ways that only mathematicians understand. Converting an arc from one system to another can be tricky (for the programmers). Most systems can usually translate lines pretty accurately, so adding the arc radius as a line is good advice. You can then recreate the arc in native Revit and discard the CAD data.

By the way, the arcs are drawn correctly, right? As a CAD manager, I would take arcs drawn by the team that in theory all had the same center, and place a "+" at the center point. The plusses mapped all over the place, when they should have all shared the same point. Also check the that the coordinates are in flat 2D space. It is very common in Acad to inadvertantly have data in space. I have no idea what Revit does with those odd coordinates. In Acad, use commands "extmax" and and "extmin" to check your z-extents. I once opened a floor plan with a 32,000 foot z extent. Mount Everest is only 29,000 feet!