3D CAD formats into Unity?

Hi All,

Unity newbie here... In my professional life, I'm a software developer in the CAD/CAM arena, but I've always enjoyed tinkering with game programming on the side.

With that in mind, I'm trying to find a path to go from the CAD modeling tools I'm familiar with (various 3D parametric solid modelers like SolidWorks and Alibre Design) into Unity.

The typical formats that are available in these tools are things like IGES (igs), STEP (stp), STL, ACIS (sat), etc.

I understand Unity's approach of importing 3D data is to target "standards", not proprietary formats. That said, many of the above *are* standard formats in the area of mechanical 3D models. I wonder if any of the above formats are in the sites of the Unity developers?

Unfortunately, there doesn't seem to be much in the way of (freely) available conversion tools to go between game-centric modeling formats and their CAD/mechanical-centric counterparts.

I've found a few such packages, but so far, haven't been able to get from "here to there".

Any tips on getting these formats into Unity (directly or via conversion) would be appreciate. In addition, I'd also appreciate any consideration from the Unity dev team for a direct import of one or more pf the mechanical modeling format standards.

Thanks,

Jeff

 

As makers of Autocad 3D Studio Max and Maya, your best bet in my mind would be to go that route - try the 3DS exporter for Solidworks and .3DS file should import fine into Unity.
Another option if you have 3D Studio Max is to simply import your Autocad file (DWG) directly into 3DS and save it as a .3DS file. Again should be fine.

 

if you import it into 3DS Max though, exporting as FBX would be the even better idea.


A general information: Unity does not import anything but FBX, Collada, 3DS and OBJ
These are the 4 defacto standards for inter application 3D data exchange, any half way professional 3D application should either support the old primary format (OBJ) or the new one (Collada)

All other formats mentioned on the page work through silent reexporting to FBX and require the corresponding application to be installed on the machine

 

Kitt / Dreamora,

Thanks for the input, but I guess I wasn't overly clear in my original description. My issue is that I *don't have* access to the typical "digital content creation (DCC)" 3D applications, but I do have access to a number of "engineering" 3D applications.

So, for me, passing anything through Studio Max (or similar) is out of the question. I just wonder why it's so difficult to translate models between the engineering world and the DCC world?

I know this is not a Unity-specific problem, as there's always been a barrier between these two disciplines, even though they're quite similar.

Dreamora - you mention "4 defacto standards" for 3D model exchange. Unfortunately, while those may be the standards for the DCC world, they're almost meaningless in the 3D engineering world. Boeing and Lockheed don't store real-world airplane model data in a 3DS file (for example).

In the engineering world, the defacto standard for 3D data exchange is (arguably) a STEP file (STP extension). If there were a way to convert a STP file into one of the DCC 3D standards (or, better yet, import it directly), that'd open up a whole new world of 3D tool possibilities to end Users.

Anyway, I don't want to debate the pros and cons of 3D file formats - I just want to get my (engineering) models into Unity.

So, to be more specific than my previous post:

1. Does anyone know of a way to convert a STEP (stp) file to something that Unity can import?
2. Is the STEP format even on the radar of the Unity dev team for possible native import?

Thanks again.

Jeff

 

the main reason why cad formats are of no interest is sometimes caused that CAD apps create plans not needfully geometry with UV etc which is the one and only thing of interest when it comes to rendering directly.

Applications that work on both ends often support some cad formats or optionally have addons to do so, but the broad majority of the 3d realtime / rendering content creation application especially the less expensive ones don't care about "exotic formats" which CADs are out of their own very specialized field.

Actually I've never even heard of a format called STEP
DXF / VRML and alike at least are somewhere known and are supported by different applications like Ultimate Unwrap3d and alike.
But highly specific apps have little to no chance to convert their own internal formats over, given they even generate data that can be used.

 

I have done what you want to do a whole lot of times in the past years: Converting CAD data to realtime-ready formats. And it's a pain in the back.

Every CAD tool I know (Catia, PowerEngeneer, etc.) works with NURBS data because it's perfectly accurate and easy to "understand" by machines and robots. But unfortunately, NURBS are of no use when it comes to realtime apps like Unity, because there's no built-in NURBS approximation to generate Polygons out of it in runtime.

So what I do now is:
1.) Export the CAD data out of the authoring tool to a format like VRML2
2.) Convert the VRML2 data to Maya binaries in an external converter - Deep Exploration, for example. This will leave you with a hell of a lot of single poly objects. Tens of thousands, probably, depending on how your complex your object is. This is because every single NURBS surface is converted to a single polygon surface in the process, and every surface you generate in your CAD tool consists of a number of separate NURBS surfaces, depending on the curvature and how sophisticated the surface is.
3.) Open Maya with the converted file.
4.) Combine all these thousands and thousands of small polygonal surfaces depending on their original materials, while always keeping the 65k-barrier in mind.
5.) Save the file and import it to Unity.
6.) Assign shaders and make everything nice and neat.

This workflow works pretty nice for me, but since you told us that you neither have Maya nor Deep Exploration at your hands, it's pretty much worthless to you.

So my answer to your initial question if there's any way to get a CAD object without any 3rd party app into Unity is: No. There's no way that I know of.

The only thing would be if you have Deep Exploration anywhere around your desk. Deep Exploration understands all major CAD formats including STEP, VRML, VRML2, DXF, DWG, etc., but also knows FBX. You could use Deep Exploration to convert directly to FBX and that format is used by Unity. So that might work. But keep in mind that you will end up with a hell of a lot of single objects in Unity what will in fact kill any good performance and manageability you might otherwise have. But it might be worth a try - IF you have Deep Exploration around somewhere. Not so far fetched since it is pretty well known in the CAD business.

 

Ultimate unwrap (not free, but pretty cheap) can import stl files (with a freely downloadable plugin), which I think, solidworks and so on should be able to create.
It can also create and edit UV maps. But, it does not do polygon reduction. A standalone polygon reduction tool that comes to mind is balancer, or polygon cruncher.

 

A bit late but maybe useful to somebody. Try the opencascade based FreeCAD project, it imports step/iges files and exports obj files which unity can apparently accept. I've not tried it myself mind you but I can confirm opencascade is very good at step imports and vrml exports. The obj export option seems to be unique to FreeCAD though. Link is here:

http://sourceforge.net/projects/free-cad/

Failing that try the conversion program Polytrans, which is relatively cheap.

 

I work in the AEC industry, and I know where you're coming from.. It is sometimes a pain to translate files from engineering formats, but Rhino is your best friend here. It opens most surface and solid model formats and exports to dwg, dxf, and obj. Plus, if you're a developer, chances are you know your way around the back end of these software, and usually you can use their API to grab the render meshes which you can output to a mesh format. For instance, for my iPHone application goBIM, I export models out of Autodesk Revit using the API to write out the render mesh to a text file similar to an OBJ.

Drop me a line if you need any advice.

 

To me, the best way to move data from Microstation to Realtime engines has been Micro-->3Dmax-->Engine.

THe worst of this workflow is that if you're working not with solids doing 3d machinery but doing Site design in UTM coordinates (big numbers) you'll find that when porting your data to 3dmax it looks quite weird. Even if you try to cheat the 3dmax by referencing the initial file to 0,0,0 coords, no error is shown but the ressult is the same, so the only way is to copy your CAD file and move it to the 0,0,0 wich is **it

 

Waht about showcase? Its eating all CAD files and put at a fbx
And the nice thing : nice rendering inbetween.

 

I forgot to mention that Politrans is an especialiced data converter that claims to convert CAD-Solids formats to "artistic" 3d formats. You could give it a try to the demo. It will remove a face for each 5 in demo mode but it will give you an idea if works or not .

 

Here's my recommendation for 3D conversions from CAD, starting with the best support:
1. Wavefront OBJ
2. STL
3. DXF

The bottom of the list would be VRML and STEP. Nobody outside of CAD has ever heard of STEP.

 

My recomendation for the ones comming from Microstation: (also aplicable to Autocad Users)

Save as DWG.

In 3dmax impor with the File Link Manager

Save export the file as FBX and import into Unity.


Super fast clean.

 

Carrara Pro does a decent job of importing STEP files.

 

I just wanted to chime in here and didnt think this needed a new thread...

I am in a corporate environment where we use very large and elaborate CAD files to plan and build assets. These CAD files costs tens of millions of dollars to create and my industry is currently looking for ways to use them after the planning phases. The idea is to continue to update the CAD files and use them in operations.

Meaning these CAD files might get updated weekly. So we are looking for a way to simply have these assets stored on a server with a virtual world where the changes can be seen in real time.

So is it completely possible (with the right people) to build a framework in unity to support CAD formats the same way it supports 3DS and Maya?

 

It may be possible to create an import script or plugin to bring in a CAD model, but the problem you are going to run into is that CAD models make very poor realtime 3D models.

I'll give you a real world example: I received a 1 MB STEP model from a client and converted it into a format that Unity can import. The resulting file was over 100 MB and over a million polygons. Many times bigger than Unity (or any other realtime game engine) can handle. We ended up spending a week creating a new model that looked identical to the CAD model, working from scratch and using the CAD model mostly for dimensions and detailed information. The end product was roughly 8,000 polygons and ran like greased lightning in Unity.

There are applications that will automatically reduce the number of polygons in a model, and some work better than others. But none do nearly as good a job as an artist and to be honest, although I've wanted to go this route I've never gotten good enough results to allow me to.

 

So my next question would be is this a engine restriction or a hardware restriction. Let’s say hypothetically I have hundreds of thousands of dollars to spend on hardware to run a persistent virtual world for 3d visualization. Could I not just beef up the system and optimize the engine to hypothetically handle a few million poly pipeline? Maximum 100-200 users. (We are currently looking for a good engine to use as a bases for our project and future projects which is why I am asking these questions.)

Or is there some kind of hard limit within the engine that causes this restriction? I actually have a digital art degree (currently project manager) and 100% agree that no amount of software or scripts used to "optimize" CAD files (or any 3D model) for polygon rendering can replace a 3D artist.

EDIT: and as a side question, has anyone tried to do application sharing or document editing in Unity? Screen Scraping, VPN, Open Office integration?

 

As I understand it (and if someone else remembers the specifics please feel free to chime in) it's actually both. Unity has a limit of (and my memory is a bit sketchy here) 32,000 polys per object, and if I recall correctly, that is imposed by OpenGL and DirectX. You can get around that limit by making sure none of your objects are larger than 32,000 polys (ie. break big objects into smaller objects) and that could probably be done in a script.

I wonder, though, if you might be better served by a different "tool" for what you want, such as SolidWorks "eDrawings" or something similar?

Don't get me wrong, Unity is a great engine, but I've found driving nails with a screwdriver usually ends in disappointing results.

 

hi

in 3dmax, wich has a very poor realtime viewer from my point ov view I move up to 2 million (2.000.000) poligons with a nice framerrate in shaded mode.

I dont agree that there are not nice polygon reducers out there. I've used polygon cuncher plugin for 3dmax and in recudes meshes from 500.000 to 50-80k without your eye notices any change.

But as you can link a dwg directly into 3dmax and export it to fbx without breakng the link there is no so huge need for a cad format.

But yes I would suggest to support some elements of the cad format such as lines, because they're lost during translation, and these lines can be very handy in unity for using them for placing elements along a line, make an objet follow that line etc...

 

Sorry Pulov but a model that is 50,000 to 80,000 polys is still pretty worthless in a realtime engine. Lots of apps will do what you just described, including Modo, Cinema4D and Blender. Nothing out there (and I'd love to be proven wrong on this) will reduce a 1,000,000 poly engineering model into an 8,000 poly game engine model with acceptable results except an artist (and a lot of work). Even the high priced poly reduction apps fail in this regard.

I still stick to my original recommendation, find the appropriate tool for the job rather than force fitting something into a task it's not designed for.

 

My suggestion would be try to convert your files to one of the following formats: fbx, dae, dxf, obj, 3ds. Unity can also import: mb, ma, max, jas, c4d and blend, but it does that by exporting to fbx and it requires 3d software for that.

I wish we had more time available, then we could consider implementing support for some CAD format(s), but at the moment we're busy enough with keeping decent support of "regular game/realtime graphics" formats.

The regular way to get something into Unity is to post your suggestion on feedback.unity3d.com and get people to vote on it.

Yes, there is 65000 limit on vertices in Unity. We have some plans to remove it in the future (but that probably won't happen in 3.0). Otherwise it doesn't have any limits for performance, so you should be able to get maximum out of your hardware. 1M polys is not a problem for modern hardware (but of course there are other limits like overdraw, memory throughput and so on).

 

Sorry for derailing the thread but I just wanted to touch on my angle of attack.

Coming from the oil and gas industry we don’t have tools like Maya and 3DS Max. I do personally, but the industry does not. That’s where my question comes from. They want to use pre existing assets (ie CAD models and data sources) without duplicating data. So if I have to convert from CAD to 3DS (or .fbx) then I am creating a duplicate of their data. This is the biggest red flag in the industry. If I have to duplicate data they don’t want it. Now I agree that CAD is a horrible format for anything other than design. It is probably the worst format you could use for things like interaction and MMO style worlds. But if what you say is true and I could just hire a team of developers to implement CAD into Unity in the same way that you have .ma implemented then that is a good thing.

Examples of some of the things my industry wants:
- Use of existing CAD
- Application sharing and persistence. This means I open an excel spreadsheet in world and edit it in world. Then in an MMO setting I can log off and my excel sheet stays open for others to interact with. They want a VPN style application sharing to where if I am running a program I can share the program in world and others can interact as if it were on their desktop.

Do you think Unity can do these sorts of things? Obviously we would be developing these things ourselves however do you think Unity is a good starting place for this type of undertaking? Our current budget is almost non

 

Hi Zergcow,

Do you think that Adobe Acrobat Pro Extended might work for you? It can open a variety of 3D/CAD formats for review and editing.
I have created some Livecycle designer apps for sharing data throughout organizations...maybe with the Smartfox Server (used in the Island Demo), Acrobat Pro Ext could be used to bring in the CAD files.

Steve

 

Pipelining the file through blender and then into unity tends to work.

Depending on the format chosen, materials might need to be UV'd again or re-applied.

 

I figured that this would be a great place to make my first post.

I am also in an engineering industry. We are looking at using Unity as a means of presenting interactive manuals and training aids for the systems that we build. Most of the engineering has been done in either AutoCad, SolidWorks, or ProE. We have a plugin (comes with Pro Edition) for Solidworks that will export files as Collada.

Does anyone have any experience with this? I am really curious to know how well all of the parts come into Unity, especially their positional data as our assemblies are very intricate and I don't want to have to tweak that in Unity.

 

A little late to see all of these interesting posts, but I have experience in using CAD data in my app goBIM which was created with Unity. The core of the app runs on a COLLADA parser that I wrote myself as I needed to read COLLADA models at run-time. I've written the corresponding exporters from various CAD applications (Revit, Rhino, Tekla, Navisworks) that export model geometry and parameter data to a custom file format (COLLADA + other xml). Zercow's idea of a persistent world wouldn't be that difficult once the pipeline was in place to export data from CAD applications. The spreadsheet editing thing really isn't in my domain, perhaps try Google Docs ? But the visualization of "live" CAD data in a shared environment is a no brainer.

 

You could use this software to convert IGES to OBJ:

http://moi3d.com/

 

from another forum, from the other side (not me)

Re: Exporting files to 3ds Max


There is always confusion and exchange of incorrect information on forums, today and all the way back to 1995 when I introduced 3ds Max users to CAD conversion. The .3ds file format is an obsolete 16-bit DOS file format originally created for CAD-3D on the Atari-ST by Tom Hudson and renamed/repurposed to 3D Studio (3D Studio is the Atari-ST CAD-3D + Antic Animator programs combined together) -- what few understand is that it drops all of the accurate vertex normals needed for proper CAD conversion. The .3ds format limits objects to 65k polygons/vertices per object, has 10 character name limits, has no vertex normals, etc. I explicitly inform all my purchasing customers to never touch the .3ds format (since most of them believe it is still the 'native' file format of 3ds Max) and always to use PolyTrans-for-MAX which bypasses all of the import/export limitations of 3ds Max.

The proper way to do SolidWorks conversions is to invoke PolyTrans-for-MAX and import the native .sldasm and/or sub-part .sldprt files. The hierarchy (assembly info), configurations, meta data, proper (and real + accurate) vertex normals, materials, etc. will all be transferred. There will always be those who use the horrible STL format, or the old .3ds format to move data resulting in inaccurate data (which it always will be), and then there is my professional user base who need to do it properly on the first go with the proper data represented inside 3ds Max. As I mentioned, lack of knowledge about file conversion, and the lack of knowledge of how 3ds Max handles imports via VRML/3ds/STL/etc has always been a main problem in general across the 3ds Max community for 1.5 decades.

The absolute defacto standard for moving SolidWorks into 3ds Max since 1997 has been our dedicated SW to 3ds Max conversion pipeline. It's always been our #1 most requested and used CAD pipeline, and simply works perfectly across the board. It works with or without a local copy of SolidWorks installed.

http://www.okino.com/solutions/solidworks.htm
http://www.okino.com/conv/imp_sw.htm
http://www.okino.com/conv/pt4max.htm
http://www.okino.com/press/press_release_solidworks_feb2009.pdf

 

JGodfrey -- I'm a CAD operator as well, in real life lol This same question come up on me a few months ago. I played around with it and .STL was the best format to import into Blender. Due to lack of time, I have not read through all of this thread, my apologies, but if you're using Blender, .STL works REALLY well, even on very complex CAD models (see disclaimer below). Reference my original thread if you want http://forum.unity3d.com/threads/117439-STEP(.stp)-file-into-Blender

*DISCLAIMER -- WARNING!!! .STL files imported to Blender (and I'm assuming ANY 3D modeling program) will result in very high poly counts. This is due to the way CAD modeling works, most modern day CAD software is 99% parametric. CAD models use multiple point (higher than 3 or 4) polys unlike Blender, which only accepts 3 or 4 point polys. So when Blender imports the .STL, it has to connect all those points with edges, creating enormous polys counts... I have not experimented with it yet, but I would imagine this would be a problem with ANY format going from CAD software to organic modeling software.

 

JGodfrey -- I just read your STEP files question. The best way to get a CAD file into Unity is going to be using a middleman. Use Blender (it's free). I couldn't find a way to get a STEP file in Blender... Use .STL, just be careful about model complexity, and .STLs import to Blender, literally, with NO problem, it works perfect. Then from Blender, you can export that file as .FBX, and then import the .FBX into Unity. I did it that way with literally ZERO problems, I was actually surprised because in the indie video game industry, NOTHING works the first time you try it.

 

Right now I am facing the same situation as you.

Any workflows or recommendations to be able to transform the CAD files into Unity supported models?

As you said, the models will be updated, so I am trying to find a way to transform the CAD files "automatically" and store them in a CDN servers or something like that to then retrieve them into Unity as an assetbundle.

Any insights will be appreciated!
Thanks!

 

SW>>RHINO>>UNITY. Work fine.

 

Ancient thread, but...

I do this all the time starting with AutoCAD... 3dsmax accepts most of the formats, but Maya probably works too, i don't know if Blender support importing IGES, etc... There is not a way to retain any data on the models (advanced inventor properties or complex hierarchy stuff), you have to eventually export it as FBX to get into Unity as well as manage the polycounts and unwrapping in your 3d app, so just get it there, then export it as FBX.

 

Hi there, it's a very old thread but a lasting problem. I wrote a blog post on that with the main intention to import CATIA models to Blender but this works as well with any other 3D program:

http://wolfig-techblog.blogspot.de/2015/01/bridging-divides-importing-cad-models.html

in short: A good export route from CATIA is to STEP and to convert this to 3DS or OBJ. I made very good experiences with Glovius, which is able to convert a lot of formats and is able to handle STP files up to 400-500 MB size.
For small file sizes one can try Freecad, but I stopped with it as my files are generally too large for Freecad.

I hope that helps.

 

With the mad scramble to understand VR/AR in the corporate engineering environments... this thread is still very relevant. Curious if there are any updates to peoples recommendations... and also curious if there is a NX/Creo/Catia pipeline into 3dsMax.

 

Doesn't 3ds max quite happy import Catia files already?

 

As others mentioned, one way to get it work using only free programs is:
* Blender: .stl to .fbx or .obj

If you need to convert first to .stl:
* FreeCAD: .stp to .stl

But be warned that files can become pretty large

 

For any CAD file for free

1. Import into Fusion 360 (or any program that can export as IGES File)
2. Export as .iges
3. Import into FreeCAD
4. Export as whatever file format you want, includes .obj that can be used in Unity

 

10 years and still going strong! And the solutions proposed still have way too many manual steps and big expensive packages for my liking.

The point about CAD files/programs is that they're about shapes and dimensions and they don't care about lighting and textures. So really the only commonality between them is triangles. I have yet to find a CAD program unable to export STL, just Plain Old Triangles. So, steering well clear of all proprietary formats:

1. Save your model as an STL triangular mesh
   
2. Either convert STL to OBJ using FreeCad etc and load that; or
3. Import STL directly into a Unity prefab using https://github.com/karl-/pb_Stl.

Maybe someday Unity will add STL import to ProBuilder (it already does export).

 

game4automation professional is able to import STEP files in edit mode but not in Playmode.

It can be purchased here: https://assetstore.unity.com/packag...e4automation-digital-twin-professional-143543