DXF / Blender 2.42 / architectural visualisations

General discussion about the development of the open source Blender

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onuca
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DXF / Blender 2.42 / architectural visualisations

Post by onuca »

I guess that every architect would love to have a powerful free / open source 3D modelling and rendering tool.

I know that Blender is a very ambitious application and seems to have aspirations to become competitive to other software on the market.

However... I just think there is not enough attention paid to the MOST BASIC / IMPORTANT tool for an architect in Blender, which is the ability of importing plans.

When you are in the hurry - you just won't play with putting the DXF through various converters and with cleaning it later on manualy ( which you must do at the moment ). It just kills all the beauty. ( not to mention lack of DWG import tool )

I hoped it will be solved in this new 2.42 version, but it seems that the import was forgotten.

PLEASE CAN ANYONE DO SMTH ABOUT IT???

or...

Maybe there is something I don't know? Is there a way to quickly and smoothly import large and complex 2D DXF's into Blender?

stiv
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Post by stiv »

I guess that every architect would love to have a powerful free / open source 3D modelling and rendering tool.
Animators and modelers feel the same way! Luckily, they have Blender.

Your message was passionate, but what exactly is the problem?

onuca
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Post by onuca »

It's all about importing complexed dxf plans into blender. Only very old format ( DXF v12 ) is supported - that is one.

Another is - loads of bugs during import - missing lines / objects scattered all over the scene, problems with splines etc.

Often objects that overlap on DXF just disapear in Blender.

No support for DWG, even the old one.

That makes the application useless - I know it is a superb modeller - but you can't even input the data correctly to start modelling!

stiv
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Post by stiv »

It has been a long while since I have done any AutoCAD. IIRC, from attempting to import DXF into GIS packages, the format is underspecified which makes some things ambiguous.

As you mention, another issue is the sheer number of versions of the spec - 8 on the Autodesk site. And that with no mention of Release 12!

If you have specific bugs - other than it doesn't work - we can get whoever does the DXF importer to look at them.

Perhaps a different exchange format is possible. Does Autocad do .obj or similar?

stiv
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Post by stiv »

Just to add a little sauce to the discussion:

DWG is Autodesk's proprietary binary format. This is not a published standard. Some parts of a file may be encrypted.

An organization, Open Design Alliance - http://www.opendesign.com - has some libraries that attempt to track the DWG format. You must join the organization to use the code or read their forums. ( takes a signed, snail-mailed application )

This suggests to me an opportunity for an architectural firm to fund some Blender development! Or a good hobby for an architect-coder.

onuca
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Post by onuca »

Great! I will post a sample DXF file on my website later on today ( and post a note on the forum ) to explain clearly what bugs I mean.

Obviously DXF is more important than DWG, because it is a kind of standard throughout all CAD software - nearly always there is a possibility to export to DXF ( e.g. AutoCAD, ArchiCAD, PowerCADD, BricsCAD, IntelliCAD, ProgeCAD - check that by the way http://www.progecad.com/ free CAD for everyone! - they all export to DXF )

Especially that I am not only pushing for coordinating with AutoCAD ( especially that it is an expensive commercial package ). I guess it is much more important to make Blender more universal.

So just concentrate on getting the DXF converter to work correct :) I am sure this could make a huge difference in using Blender as a competitive package to 3Dviz or max in architectural renderings.

PS Unfortunately my company is devoted to 3dMAX, however when I finally open my own one I would love to use Blender and support it's development in a more material way!

stiv
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Post by stiv »

onuca wrote:Obviously DXF is more important than DWG, because it is a kind of standard throughout all CAD software - nearly always there is a possibility to export to DXF ( e.g. AutoCAD, ArchiCAD, PowerCADD, BricsCAD, IntelliCAD, ProgeCAD - check that by the way http://www.progecad.com/ free CAD for everyone! - they all export to DXF )
If you poke around on the Open Design Alliance website in their White Papers, they make exactly the opposite argument that DWG is more important. Essentially, DXF is a sloppy, underspecified format that exists in too many versions and can contain encrypted data. Hence, their focus on reading native DWG format.

onuca
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Post by onuca »

I have just read their White Papers. Well clearly I was very very wrong... On the other hand not every CAD package can save / export to DWG...

Anyway, the conclusion is that one way or another a DWG import script should really be implemented into Blender. Looks as if there was no point in developing the DXF format if that is so much worse.

Still as an 'end user' I just won't be able to do that by myself... Though I really wanted to attract more attention to that problem.

Meanwhile the DXF file is there:

http://kpgroup.w.interia.pl/0001-GA-PZ-100.dxf

I have removed all the unnecessary data to clearly mark where the problem is.

Generally if there are two or more polylines aligned on top of each other Blender won't import any of them ( that's probably not the best explanation, just try and see ).

I had to explode them all in CAD and join again in Blender to make it work. Obviously for a small project like this it is not a big issue, but imagine e.g. a large opera building with a complex plan...

Ideally you want to get one object for each polyline - any solution to that?

LetterRip
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Post by LetterRip »

stivs,

dxf was done by zr in the NaN days, it was a 'quick hack' to allow them to import some stuff they needed. Ton has been the one doing bug fixing on it, but I don't know if he will fix missing feature/incompleteness bugs.

That is why I suggested integrating a better supported dxf importer library as a SoC project,

LetterRip

jedrzej_s
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Location: Poland

Post by jedrzej_s »

Hmmmmm... Yes... We need good DXF support in Blender...

joeri
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Contact:

Post by joeri »

I'd say ban all import and export of closed formats.
If that makes me sound like a GNU then tough luck.

I find it a waiste of valuable time to try to keep up with this kind of stuff.
If somebody wants to; (as SoC) great; have a python script, and blaim the script writer for mistakes. Stop bashing blender for not being compatible to expensive packages. (Mail your Autocad reseller you want it to export .blend files! That's what you are paying license fees for, for them to be customer compliant)

"That makes the application useless"
Tss,... I bet Orange did not import 1 dxf/dwg file.

So how did you get the dxf in the first place?

Alvaro
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Joined: Thu Oct 24, 2002 6:45 pm

Post by Alvaro »

DXF is pretty dead for 3D content. Anything you want in that regard could be done by the 3DS format, also supported by any CAD package out there. Better a good 3DS importer IMO.

DXF is not an standard anymore, each time that a new DWG specification is released, new DXF specifications are created too, although DXF core remains (more or less) the same I believe. I think it would be a mistake trying to follow Autocad pace in that regard, Autodesk releases a new DWG format every two years nowadays (every two ACAD releases in fact)

DXF importer need some clean-up for:
- In general better importing of 2D stuff inside those files.
- Z coordinates
- polylines
- splines
- Acepting blocs and translate them as linked meshes.
- regarding 3D objects, at least CAD meshes.
- Some layer compatibility,
- Bugs clean-up regarding coordinates translation.

But one of the most important features that this new importer should have is the ability to ignore some parts of a DXF file (innecesary; unsupported; encrypted stuff) without screwing the whole process up.

And that's all IMO. But take into account that YOU COULD END UP developing not a generic DXF importer but an Autocad DXF importer, which in many cases could be a drawback, for example for users of other CAD packages, which still use old DXF standars.

The target of Blender should be users of simple CAD packages with reduced or any options regarding 3D. For example, Autocad LT.

Anyway, Intellicad solutions and their open formats is the way to go IMO, in case Blender developers want to create some serious CAD interface. Besides they could provide good advice to Blender developers.

As I said in Elysiun, DXF current situation is a bit complex.
Stop bashing blender for not being compatible to expensive packages. (Mail your Autocad reseller you want it to export .blend files! That's what you are paying license fees for, for them to be customer compliant)
So true. Very expensive licenses I would say. Besides, many people should be aware that complete CAD packages do have good 3D tools and (no so good) internal render engines, although they have plug-ing aswell for good external raytracers.


PD: Open Design Alliance could be another option in that regard, which promotes OpenDWG and OpenDGN (Microstation). As you can see they seem not very interested in DXF format, here is why:

http://www.opendesign.com/about/whtpaper/whynot.htm

Alvaro

PD: well seems that in fact Intellicad is member of that alliance and uses OpenDWG. The Open Design Alliance web, for those interested in the CAD world, is very interesting. It explains some facts about CAD history.

stargeizer
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Post by stargeizer »

Hmmm.. Dxf blues again...

The DXF format is fully documented in each release of Autocad (the full version, not LT's) and they change it from time to time to adapt to their needs. Also they offer in the autodesk site the full documentation to the DXF format anyway (http://usa.autodesk.com/adsk/servlet/ps ... eID=123112) so you can consider it "open" to see and use, but not open for modifications.

About the 3ds format, autodesk is trying to kill it. If you have enought money to buy/update any autodesk product from 2006 and earlier to the 2007 series, you will see that they removed the support for exporting 3ds formats (you still can import it, for now), and 3ds 8 will use another format for default. So the 3ds format will be dead in the future.

About the encryption used in DXF formats, they only encrypt the propietary ACIS data, and that's done due the legalities in the U.S. and patents that spatial have over the ACIS format. If you are wondering what is ACIS data, in autocad terms are the "SOLIDS" objects, or 3d objects with volume data asociated. The rest is open and documented. Even if anyone can defeat the encryption (very trivial task in fact... myself have done it in lisp... but not use anyway) ACIS format are fully undocumented and patented, so the legalities of using it would be questionable in some countries.

Make a better support for DXF would be good for cad users out there, that needs to use blender. After all, Autodesk can't really kill that format, since there'are production machines that relies in that format. But i think that nobody should expect full 100% compatibility between CAD software and blender itself, at least on the 3D part of it.

Best Regards.

J.

dfelinto
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Location: Rio de Janeiro, Brasil

Post by dfelinto »

The QCAD community edition has his source code released under the terms of the GNU General Public License (GPL), and available to download.

The Import DXF function is great and working.

http://www.ribbonsoft.com/archives/qcad ... src.tar.gz

Better then it, only ask for google part of the code of sketchup :) (What it is not bad idea)

Somebody knows if some student accepted to work in the DXF in the GSOC?

Regards,
Dalai

Alvaro
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Post by Alvaro »

About the 3ds format, autodesk is trying to kill it. If you have enought money to buy/update any autodesk product from 2006 and earlier to the 2007 series, you will see that they removed the support for exporting 3ds formats (you still can import it, for now), and 3ds 8 will use another format for default. So the 3ds format will be dead in the future.
I agree that Autodesk is going to kill 3DS, if not already killed, but I don't believe for a moment that Autodesk is going to leave DXF as the only option for exporting 3D content, because I do believe that DXF specification is somewhat limited for this kind of stuff.

Besides, Autodesk may be interested in dropping the 3DS format, but that could be not the case in other important CAD tools.

The question is if newer Autocad Releases will have more options for exporting 3D stuff apart from DXF and if Blender can support them.

I don't have access to the latest Autocad releases, but I suppose that there should be at least a MAX exporter, but it would be interesting to know if there are other formats available.
they change it from time to time to adapt to their needs
AFAIK, there is a new DXF specification every time a new DWG specification is created, every two years.

The question in my opinion is if we can expect to have a coder maintaining the DXF importer at that pace.
About the encryption used in DXF formats, they only encrypt the propietary ACIS data


Solids, in nowadays CAD tools, is the most important part of their 3D content. If we can't import solids by the DXF importer, then we need two options for importing CAD content, one for 2D entities (DXF) and another for 3D solids, the 3DS format nowadays.

The question in my opinion is if it is worth the time and the effort of Blender coders to defeat the encryption, when there are other importing options already coded (3DS, LWO, OBJ)

The important question is if Autocad will have a OBJ exporter for example in the near future. In that way, the work in the Blender DXF importer could be focused only in the 2D part, the most sensible option IMO.

Alvaro.
Last edited by Alvaro on Thu May 18, 2006 7:33 pm, edited 1 time in total.

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