A minor question on AutoCAD import

Thanks for this info. Yeah, I see your point–you can redraw over one of the imported faces and avoid deleting. However, I sort of thought that having coincident geometry is a bad thing. When doing it the way I’ve been doing it, drawing a quick line from one side to another, it is easily visible and can be accurately erased.

I will definitely check out those extensions…thanks.

After I posted my question here I did find an interesting workaround on the AutoCAD side. After you create your closed polylines in AutoCAD you can change them to regions, which are 2D AutoCAD solids. (A very simple process). A face is then created in AutoCAD. When you do the import, in Sketchup, in ‘Options…’ make sure you have ‘Merge coplanar faces’ enabled. You end up with faces in Sketchup.

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Sketchup geometry sticks together, so if it is in the same context the two edges become one, no coincided geometry to worry about.

Ok, yeah, good point. I did know that (about the stickiness); I just didn’t apply it when thinking about this specific issue :slight_smile: But let me explain this in a different way. The molding profiles are fairly ornate…have lots of detail to them, so when just quickly adding a line it would be very, very easy to put a line where you didn’t want it. In other words have it not lay exactly on another line. Of course all the molding samples have a straight line on the back (where the molding would hit the wall), so that would be a good place to locate an additional line to cause a face to be drawn.

But, as I stated, did find a workaround for this right inside AutoCAD, that eliminates the need to draw a line. However, I appreciate your point here as it underscores this basic aspect of Sketchup…stickiness. I’m sure there will other issues of AutoCAD import that will affected by all of this.

Totally understand, don’t want to add edges where they aren’t needed.
Can be a problem too with cad imports not being flat or having edges sticking up due to some cad programs ignoring the z axis. You can end up joining to an endpoint the isn’t at 0.

Yes, definitely; having random objects not respecting z=0 is a real hassle. However, in the situation I was working with, using polylines, these are strictly 2D objects. AutoCAD won’t let you create the various segments at different Z elevations. In other words they are always flat. I guess the exception to that would be if the user had their drawing elevation set to something non 0, but then the entire closed polyline would be at that non-0 height. In other words, it would be flat; just not at 0. Now…AutoCAD lines are a different issue…you can definitely end up with a ‘non-flat’ group of line entities if you are not careful. But I think AutoCAD as an app is pretty good at keeping track of ‘Z’…a lot of problems with AutoCAD and this issue is with user error, and sloppy CAD work. But as you mentioned, other CAD programs may not be as good at this. Heh, now I want to do a test to see what happens when Sketchup encounters a ‘flat’, properly 2D polyline, BUT one that’s drawn at an elevation other than 0. Does it put it down to 0 or does it respect it’s elevation.


You might also wanna check this thread:

100% here.

What about 3D polylines? You can certainly do it with these.

Right; but I wasn’t talking about 3D polylines. Hey, I’m trying to focus the discussion! :slight_smile:
Speaking of which…I don’t think 3D polylines are used that much in AutoCAD…definitely compared to 2d Polylines. I think that holds true even for 3d modeling where the common workflow would be to use lines or polylines(2d) and use commands such as ‘extrude’. And because of that, most people use the term ‘polyline’ to refer to the commonly used 2d variety, rather than specify ‘2d’ specifically.

Mike, thanks for this info. This is interesting, and I’m new to thinking about geometry efficiency, at least as far as Sketchup is concerned. I have some experience with it using 3ds Studio.

Before digging into this and checking out the thread you suggested and the extensions, does weld really have the ability of combining multiple edges in one ‘polyline’ in Sketchup? I know that my profile collection is each a single closed polyline in AutoCAD. They are as about efficient as possible in AutoCAD. Each of the single polylines has around 13 - 27 segments, depending on factors that you would expect, size, amount of curvature and detail, etc. As I said, they are all closed, no redundant or coincident / overlapping segments. I actually can see that the segment count is similar between Sketchup and AutoCAD. I can see the segment count in AutoCAD by exploding the polylines, and ‘Entiry Info’ in Sketchup pretty much shows the same number of Edges. Unless I’m misunderstanding my quick look at Weld, it sounds as if Weld will join all of these individual segments, and create a ‘polyline’ like an AutoCAD polyline entity. Is that a correct reading of this? If so I’m wondering what an extrusion in Sketchup would look like after a Weld compared to pre-Weld. Would it eliminate lines/edges along the Z surface? Or lessen them? You see, the profiles that I have, as you would expect, have a lot of curvature to them. If each profile is converted to one edge by Weld, I have a difficult time imagining that it would eliminate a lot of busy lines on the Z surface. And if this is the case, what good would Weld do, really?

Yes. It does exactly that.

that is an interesting insight, thanks for sharing

Yes, thousands of layers, nothing in the right layer, layers in blocks and blocks not in that layer…3d blocks in 2d drawing, lines with different z heights, entire drawings hidden in a clipping plane only to show 1 small detail…
coordinates in the millions of units, metric and imperial line/hatch scales mixed in the same drawing… exploded hatch patterns… linetype scales set globally and individually…

Autocad is wonderful :slight_smile: miss it dearly :slight_smile:

forgot to mention splines… such a joy…

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Yeah, it’s often bizarre getting an AutoCAD file from someone you never have worked with before. It seems there are always ways of doing things that you aren’t used to. You learn AutoCAD, use it for a few years and you sort of think that you understand how it works and that most others are using it like you are…not always the case. Often when I get an AutoCAD file from someone, it’s almost as if it’s a puzzle or test of either my patience or my skill level. Then there are the little ‘bombs’ in each drawing that are the result of just plainly not doing things the right way. One of my favorites are people that don’t use ortho when doing standard architectural 2D working drawings. But I would have to say that the tops on the list, the grand prize goes to folks who are allergic to the use of object snaps. That drives me absolutely nuts seeing a floor plan with 1) ortho not used consistently and 2) objects snaps not used. You may as well be using an etch-a-sketch. :slight_smile:


I work mostly on non-orthogonal plans for restoration, but there is no excuse to not use osnaps (wouldn’t know how to precisely rotate a door-frame without osnaps).

LMAO I blame the user NOT the tool. Unless one is using an AutoCAD vertical product it does NOT add layers on it’s on. Nor on the “wrong” layer etc… that’s on the user. I’ve had had bad files from Acad, Vector Works, PowerCADD, ArchiCad, etc…
Splines are fine in the correct situation.
Honestly some one didn’t know what they were doing, nothing more.

Lol much like getting SU files with no groups or components or layer structure as well. I’d imagine Gsharp also blames SU and not the user? :wink: j/k We’ve ALL gotten bad files from others.

Minor note, I drew some closed polylines, closed 3d polylines and some closed splines in Acad 2020 and was able to drag and drop into the current SU with no errors. Sure I had to “close” the face on the closed pline :confused:

A tool that allows users to make such a mess is a bad tool… yes I blame the tool… if it was only the user at fault then it would not matter what software we use…if you consider them parity why not still use autocad?

LOL sure blame the tool, what ever good sir. I DO still use AutoCAD, every day (and other software as needed). My files DO NOT create “thousands” of layers auto-magically, my end points meet, my lines are parallel when I want them to be, items on the correct layers (that I put them on) and so on and so forth.

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