DWG Export File too big

I’ve been working with some .dwg files and have had some issues with filesize. If I open a .dwg in Rhino and then re-export it as .dwg, the file size spikes pretty dramatically in the new .dwg. I have been fiddling with the .dwg export schemes, and have managed to improve it a little, but not enough. Does anyone have an example of good settings for controlling the filesize of a .dwg export? Thanks!

Just use export scheme Default. It will export the curves exactly as they are in Rhino.

I would not use Default in this case, it explodes polycurves and tessellates splines into polylines. I would use the “2007 Natural” option instead.

I have been using 2007 natural as my go to setting, however, that is still resulting in a file that is about 2x larger. I tweaked it a little bit as shown in these pics

This is working better but still increases file size significantly. It’s odd since I am making no edits to the file at all, just open in rhino then re-saving as .dwg

Hello - - what is in the files, anything other than curves and polylines?


Well, .dwg is a different format from .3dm, it may well be in this case that .dwg files are just naturally larger…

Oh I don’t think I was very clear. I am opening a “.dwg” file in Rhino and re-saving it out as a new .dwg, There are no .3dm files in this process. I’m doing this all in rhino as part of a python script that is batch editing a bunch of .dwgs. I’m really only in Rhino because I’m more comfortable with scripting in the Rhino environment.

@pascal, there is mostly just curves, polylines, some text objects, and points. no 3D objects.

I always check my dwg files before sending. I’ve never had a problem with tessellation. Or any complaints.

Hi - could you please post a DWG file that we can open in Rhino and that you see increasing in size when exported from Rhino?

You are correct, it used to be that way in older versions, but it doesn’t anymore, sorry for the mis-info. However it does still explode polycurves on export.

Yes, the exploding curves part is odd. It’s still the best option for my work. I went down a frustrating rabbit hole. Trying to find the Export setting that didn’t massively increase file size/convert degrees. Rhino doesn’t make it easy.

@wim sure I’ve uploaded the file here curbs.dwg (2.4 MB)

There are some block instances in the file, which I have tried exploding and then purging out, which doesn’t seem to solve the problem. Thanks!

This isn’t a huge deal with files like the one I uploaded (2.4 MB), but I am dealing with some very large files with contour data for a whole city which are upwards of 1 GB. I don’t want to go ballooning the filesize of those anymore than they already are.

Post the Rhino file so we can figure the best export scheme.

There is no Rhino file, I am just opening the .dwg file with Rhino changing layer names, and then saving it out as a new .dwg curbs.dwg (2.4 MB)

Yeah it doubles in size with the default setting. I see it adds another 10000 points to the curves. I wasn’t expecting that.

Yeah, I can’t explain the file size difference either… I exported all as 2007 Natural, then I re-imported the file. Then I did a SelDupAll and hid all the duplicate objects. There were only 16 small arcs left that weren’t considered exact duplicates, and they looked nearly identical in any case (same # of control points).