DWG Import into SU
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Hi all,
I've been playing quite a bit with importing DWG files into SU and have come to the sad realization that SU does not handle DWG import too well. This is dealing specifically with importing polylines with Z elevations (contours). Here is how I arrived at this conclusion:
- In AutoCAD, I assured myself that all polylines had a Z elevation, were contiguous, and if they were a closed polyline, it was indeed closed.
- I imported the DWG file into SU. SU reported back 2 layers and 276 poly-lines imported. Everything else looked normal. Ok so far.
- Upon closer inspection, I found that the lines start overlapping each other. Even though they are on different Z elevations and even in AutoCAd they clearly do NOT overlap.
- One would have expected that the closed polylines would have meshed together, but no dice.
Now here's where it really goes off the edge, IMO:
- I draw a large rectangle down at elevation zero and drape the contours to the rectangle. Why? because I want to push-pull the contours to their respective elevations and have a 'stepped effect' like Donna's model (see the forest thread).
- I connect end contours with other edges to hopefully have it close and create faces - nope.
- Again, upon closer inspection, I see that since I have draped, i now have open areas where I clearly didn't have them in the other situations. Almost always they are small little openings that cannot been seen without zooming way down into the model.
I know thre are rubies to fix some of this stuff, but I am wondering why it is this way in the first place? Maybe that's the reason why Google dropped dwg in favor of Collata?
I also read somewhere that if I enlarge my AutoCAD drawing, say 100x (scale up) and import it into SU and then scale it back down, it may help with this situation - but I haven't tried this yet. The ability to semi-accurately read in files form AutoCAD is imperative to my line of work. But I'd like to have it without lots of hoops to jump through - pipe dream?
Anyone have any ideas?
Rick
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Hi Rick, hi folks.
Make sure that, when importing the CAD file, you uncheck the option to preserve the drawing origin.
With contours, there is a great chance that your drawing end up many miles away from the axes origin of SU. This can create problems.
Also, make sure that you import with the right units. Importing meters as millimeters can also create a lot of problems since SU has difficulties with very small edges (less than about 1 mm or 1/16 inch).
Just ideas.
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@jean lemire said:
Hi Rick, hi folks.
Make sure that, when importing the CAD file, you uncheck the option to preserve the drawing origin.
With contours, there is a great chance that your drawing end up many miles away from the axes origin of SU. This can create problems.
Just ideas.
I beg to differ, but if you have an imported plan and later you decide that you want to import more then preserving the drawing origin is imperative. For example, I import the contours and get them the way I want them in SU. Now I want to import roads, fences, etc. Without the same drawing origin, then it is almost impossible to line up things properly. At least that has been my experience.
Rick
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I agree Rick, but unfortunately, SU just does not tolerate models that are far from the origin.
I use this trick to help though. In my CAD plan, I draw a triangle (or any object really), rather large, to the bottom left of my CAD model. And when I export things from my CAD file, I always use the wblock command. So I select all contours, AND my triangle, and then wblock it out to a separate file. Then I import that into SU, and I force it to ignore the model origin. What this does is it then lines up that object I drew on the SU origin. And everything I export from CAD from then on, I just export that trianlge shape alone with it and it wil always import right where I want it. Or if ever these is a problem, I always have that triangle that gets imported and I can then rotate and scale the new import so it fits perfectly with the existing.
Sounds harder than it is and so far it has worked perfectly for me. And I think it might help with your bizarre linework.
Chris
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