1) Sometimes your app doesn't support DXF very well (e.g. Blender's DXF importer has been getting worse, or QCAD DXF only supports 2D, and you might need 3D data)
2) It can support conversion of absolute coordinates to a geolocated model (CG apps don't do absolute coordinates)
3) You can then manipulate it programmatically and make the DXF more useful (e.g. generate more geometry, add unit definitions because DXF is unitless from what I read, add georeferencing metadata...) and then connect to the IFC pipeline: clash detection, drawing generation, model federation, etc.
@magicalcloud_75 would you have a series of samples of DXFs I can use to test to see whether or not I can convert it?
Cool, I also have a highly incomplete DXF to IFC converter in File::IFC called ifc-dxf2shell.pl. Though ezdxf looks like a much better framework for doing this.
As ezdxf is successor of dxfgrabber (blender's dxf io) we should take a look at updating blender's dxf io using this new lib, perhaps as external addon in a first step to be able to release faster than blender, and once production ready submit to bf for inclusion.
Maybe we should talk about this with Lukas Treyer as it is the active maintainer of blender's dxf io.
Providing users with a safe dxf io must be high priority thing.
Georeference removal is pretty tricky under limited precision context.
@stephen_l on the LibreDWG page is says "Among the example applications we wrote using LibreDWG is a reader, a writer, a rewriter (i.e. saveas), an initial SVG and Postscript conversion, converters from and to DXF ..." does this mean it is also a DXF writer? Surely if it can convert then it muct be a good DXF writer ... I'm a bit confused as the the difference between convert and write. GRASS GIS seems to the only project that has implemented LibreDWG - and they have resources. They might be worth reaching out to.
@magicalcloud_75 said: Now, you did a good job hidding it. :P Where is it now?
Search for DXF: https://wiki.osarch.org/index.php?search=dxf
Search for DWG: https://wiki.osarch.org/index.php?search=dwg
"DXF" is mentioned in the software directory 10 times (usually linked to the DXF page). "DWG" just five times in connection with LibreDWG, linked to the DWG page.
So I don't think I've hidden them at all - I was just encouraging people to take a look around the website. Is there somewhere you looked @magicalcloud_75 where they should have been mentioned?
Where did you put the links to page 'IFC in DWG', the one i started?
It seems to be lost in space, out of directory. I mean.
Your stories about DXF and DWG are a bit short
And you completely skipped the ODA history on DWG. I think, the real trouble with DWG is the attitude of Autodesk. There really no reason to keep DWG proprietary in 2020. Autodesk versus ODA, the rest of the world.. Why don't we just Make DWG as open as PDF. Nice link btw. QCAD, i will try!
I am just happy to see involvement of BSI and OGC in ODA development. I mean, i think its not of much choice the way DWG is done these days (post above). Maybe one day open will become truly open. I have some plans to do an interview with the old chairman of ODA. He is from the Netherlands. :) What would you like me to ask him?
@magicalcloud_75 do you mean this page? https://wiki.osarch.org/index.php?title=IFC_import_in_DWG it's in both the DWG and IFC categories/lists. If it was on the front page then yes, I would have removed it from there as it needs to be somewhere more specific. That's part of why I've been working on categories, much better than manually maintained lists split by topic. You are free to add it where you think it is relevant.
Wikipedia has good articles for DXF and DWG (the DWG one I've spent a lot of time on a few years back). I see no reason to duplicate Wikipedia content.
Why do you keep calling DWG "open"? What do you mean when you say open? It is a closed, partially encrypted, proprietary format basically controlled by Autodesk. Anyone who loses compatibility with AutoCAD has basically stopped using DWG.
If you'd like to make a new thread about your interview with the former ODA chairman I'd be very happy to suggest some topics - especially about the legal troubles with the supposed trademark on "DWG"
Anyone had a look at acis support? Ezdxf won't do it ( https://ezdxf.readthedocs.io/en/master/dxfentities/body.html ) but at least it encodes/decodes between binary and string format, so the rest could easily be done outside. Without acis, dxf is basically 2d-only, except for 3dface / 3dmesh entities, which i've ever only seen used in land surveys (ok it's something already).
(From wikipedia) As AutoCAD has become more powerful, supporting more complex object types, DXF has become less useful. Certain object types, including ACIS solids and regions, are not documented.
This is why we can't have nice things :( Boo Autodesk.
FWIW, when I wrote that DXF2IFC script I had a 3D DXF - I guess it had 3D polyface entities, which I was able to parse.
Comments
I've added DXF & DWG to the wiki - see if you can find them :-)
I've added ezdxf to the wiki - it's a fantastic library! I've started a little DXF to IFC converter here: https://github.com/IfcOpenShell/IfcOpenShell/commit/7f6c9e61c89dce062fa240c7def5ac0b65400627 - I tested it on one very simple file that I needed to use anyway, and it worked well.
The converter is useful because:
1) Sometimes your app doesn't support DXF very well (e.g. Blender's DXF importer has been getting worse, or QCAD DXF only supports 2D, and you might need 3D data)
2) It can support conversion of absolute coordinates to a geolocated model (CG apps don't do absolute coordinates)
3) You can then manipulate it programmatically and make the DXF more useful (e.g. generate more geometry, add unit definitions because DXF is unitless from what I read, add georeferencing metadata...) and then connect to the IFC pipeline: clash detection, drawing generation, model federation, etc.
@magicalcloud_75 would you have a series of samples of DXFs I can use to test to see whether or not I can convert it?
Cool, I also have a highly incomplete DXF to IFC converter in File::IFC called ifc-dxf2shell.pl. Though ezdxf looks like a much better framework for doing this.
As ezdxf is successor of dxfgrabber (blender's dxf io) we should take a look at updating blender's dxf io using this new lib, perhaps as external addon in a first step to be able to release faster than blender, and once production ready submit to bf for inclusion.
Maybe we should talk about this with Lukas Treyer as it is the active maintainer of blender's dxf io.
Providing users with a safe dxf io must be high priority thing.
Georeference removal is pretty tricky under limited precision context.
@Moult please add your comments or a link to them to the https://wiki.osarch.org/index.php?title=Drawing_Exchange_Format_(DXF) page
@stephen_l on the LibreDWG page is says "Among the example applications we wrote using LibreDWG is a reader, a writer, a rewriter (i.e. saveas), an initial SVG and Postscript conversion, converters from and to DXF ..." does this mean it is also a DXF writer? Surely if it can convert then it muct be a good DXF writer ... I'm a bit confused as the the difference between convert and write. GRASS GIS seems to the only project that has implemented LibreDWG - and they have resources. They might be worth reaching out to.
@duncan Convert imply read from another format before writing.
As far as i can tell the actual state of dxf writer is still a bit limited.
Draftsight is not free anymore.> @duncan said:
Now, you did a good job hidding it. :P Where is it now?
Search for DXF: https://wiki.osarch.org/index.php?search=dxf
Search for DWG: https://wiki.osarch.org/index.php?search=dwg
"DXF" is mentioned in the software directory 10 times (usually linked to the DXF page). "DWG" just five times in connection with LibreDWG, linked to the DWG page.
So I don't think I've hidden them at all - I was just encouraging people to take a look around the website. Is there somewhere you looked @magicalcloud_75 where they should have been mentioned?
Where did you put the links to page 'IFC in DWG', the one i started?
It seems to be lost in space, out of directory. I mean.
Your stories about DXF and DWG are a bit short
And you completely skipped the ODA history on DWG. I think, the real trouble with DWG is the attitude of Autodesk. There really no reason to keep DWG proprietary in 2020. Autodesk versus ODA, the rest of the world.. Why don't we just Make DWG as open as PDF. Nice link btw. QCAD, i will try!
I am just happy to see involvement of BSI and OGC in ODA development. I mean, i think its not of much choice the way DWG is done these days (post above). Maybe one day open will become truly open. I have some plans to do an interview with the old chairman of ODA. He is from the Netherlands. :) What would you like me to ask him?
@magicalcloud_75 do you mean this page? https://wiki.osarch.org/index.php?title=IFC_import_in_DWG it's in both the DWG and IFC categories/lists. If it was on the front page then yes, I would have removed it from there as it needs to be somewhere more specific. That's part of why I've been working on categories, much better than manually maintained lists split by topic. You are free to add it where you think it is relevant.
Wikipedia has good articles for DXF and DWG (the DWG one I've spent a lot of time on a few years back). I see no reason to duplicate Wikipedia content.
Why do you keep calling DWG "open"? What do you mean when you say open? It is a closed, partially encrypted, proprietary format basically controlled by Autodesk. Anyone who loses compatibility with AutoCAD has basically stopped using DWG.
If you'd like to make a new thread about your interview with the former ODA chairman I'd be very happy to suggest some topics - especially about the legal troubles with the supposed trademark on "DWG"
Anyone had a look at acis support? Ezdxf won't do it ( https://ezdxf.readthedocs.io/en/master/dxfentities/body.html ) but at least it encodes/decodes between binary and string format, so the rest could easily be done outside. Without acis, dxf is basically 2d-only, except for 3dface / 3dmesh entities, which i've ever only seen used in land surveys (ok it's something already).
This is why we can't have nice things :( Boo Autodesk.
FWIW, when I wrote that DXF2IFC script I had a 3D DXF - I guess it had 3D polyface entities, which I was able to parse.