Chaos Corona Forum
General Category => General CG Discussion => Topic started by: Mr.Schorsch on 2015-03-20, 15:53:15
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Hi to all you Corona friends
I have a Problem. We got .step files directly out of Solid works from a client witch we need to render in high Quality and even with Close ups. The shape of the products is rather curvy but also with hard cuts. Out of some years of experience I know, that it is not possible to remodel the stuff in a time the client will pay us for.
I know there are always problems with converting from nurb to poly but after all this years there must be a proper way to get this stuff done.
The .step files come into max as Body objects, witch are basically kind of good interpreted by max itself. But it is just 90 % good and fails in important areas of the model. Especially where round goes to straight it leaves open edges and this is causing reflections to interrupt.
So if anyone of you, great guys here in the forum, knows some good tool, script or external program pleas let me know.
I already tired some ( power translate, Okino poly trans, Rhino) but I never got good looking results.
Thank you and have a nice weekend.
regards!
Gregor
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Honestly I don't know anything about this type of objects, but which Corona version are you using? I think in some of the bugfixes there was a "body object" fix included.
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Hi. So fare the best result I've achieved was by using the Inventor Fusion software. Back then (2012 or so) it was part of the AutoCAD installation (suite), but now I think it's a cloud thing. Still got the old one installed.
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Use Rhino 3D to convert your file.
https://www.rhino3d.com/
I think you can even use the demo. Rhino is awesome!
- Shawn
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@ Maru
it is not a corona related problem. I am running the Corona 1.0 and I am happy with it. It is more or less a basic problem of the whole 3d world I think.
Without the corona round corner setting in the mats I would be totally screwed in this project. So from the Corona side on, It is all good.
@ astrofalcon
I played around with the rhino demo, but maybe not long enough. I hope I will achieve something decent after giving it a bit more time and practice. How would you convert it. In rhino from nurb to poly and than give it out as a obj or something. ...If you have a workflow you can describe in some words you would save me some time.
@PROH
I'll see if I am able to get a demo and give this one a try as well.
Thank you for the quick replies
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is it possible that you upload a screenshot of the model? or some problematic part of it? ... depending on the geometry I use different workflows ...sometimes .step files get very accurate converting them to .iges or .stl and in most cases they get very well defined in .obj, but you have to change some settings at the moment of export. I do this always using Rhino. Even sometimes exporting to .fbx you will get a really smooth mesh in 3dsmax.
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yes, please add screenshots.
There was a bugfix for body objects recently, but we still have one bug report open where the CAD import just creates a geometry that is so screwed up, that it fails to render properly. Just manually cutting the extremely thin triangles does help, though
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In my daily business, I render in 3ds Max objects coming from CAD software (in .stp format). I have experimented a lot and the best solution I have come so far is passing through Rhino (great software!). Convert your .stp to .obj with special care to edge density, edge length and the other parameters. Rhino has lots of options that allow you to have full control on the mesh you are generating! If you must render close-ups, you'll need high triangulation, so you must consider the purpose of your model before conversion...
Actually there are lots of things you may want to do in Rhino to prepare a model for rendering: edge chamfering, grouping parts by material etc... it's a world!
When you're happy with the mesh, import, convert/assign materials, and have fun!
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Hi Mr.Schorsch,
I have to deal with CAD-data a lot everyday, in Max the body objects can get quite buggy though.
Then truth is (as far as I know) the Body Objects plugin implemented in Max is a cut-down version of the PowerNurbs package.
After having bought the full one i didn't have any issues in Max while importing STEP or IGES Data (although depending on your package you might need to buy a special version of PowerNurbs, e.g Jupitor Translator [JT]is not included in the PowerTranslators Pro).
There are 30-days trial versions on their page, if you find time check it out! Up till now this was the most ideal way to handle CAD data in Max, without going through the pain of data conversion.
As far it goes for Corona, it works perfectly with PowerTranslators Pro, i have done a lot of tests. All but one produced nice clean renderings with no normal problems. The one time where it went wrong, it was obviously due to bad Siemens NX > STEP conversion. Nevertheless this case is very interesting, because the same geometry rendered clean in Alpha 0.6, in 1.0 it came out broken. I will dig up some screenshots on monday and post them here for comparison, perhaps you guys know the cause.
CheerZ,
G.S.
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Hey guys
First of all, thank you for all the replies. It really looks like, I need to get used to the fact to learn how to handle the basics of rhino. Puhh... another program on the list... anyway...
Sorry... I can not upload screenshots. The projects NDA does not allow it. But it is definitely nothing relating to corona, as the render engine of my choice.
As I said... it is a basic problem of polys and nurbs... and all the steps (haha) in-between.
@Gabriel Sumner
I checked out PowerTranslation and it looked like a slightly advanced version of the max body object (as you already mentioned) Maybe I did something wrong but even this tool gave out shitty results in some areas. But I must admit the object we have are really complex. Very curved with tons of screw threads. Its a mess.
I heard of some other tools that might do the job... I keep you updated.
And again.. Thanks a lot!!
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Check out MoI ( moment of interest) it is a small cad program for ca. 300$ which gave me the best results in the shortest amount of time. It is closing the geometry nearly perfect and gives out decent meshes. For now this seems to be my favourite.
The web side looks shitty and/or 90' style but the tool seems to do its job.
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Installed demo of MOI, but didn't like it at all - results was much worse than 3ds max's body objects. Maybe i'm doing something wrong?
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Indeed, MOI has a very exotic UI ;) But when you get used to it, you soon realize that you can get incredible results in the shortest amount of time. I too use it in everyday production, mostly as a chamfering / filleting tool.
The one particular issue with it, is when your input files get too large - like 100 mb or so. Then it takes a significant amount of time to open them, although eventually they open up successfully. Never tried rhino though, a lot of people told me that it's a great tool.
Now to the normals issue. For me the same thing, NDA, can't show too much here unfortunately.
But i digged up one comparison. On the left is Alpha 0.72, with the broken normals issue. 1.00.01 produced the same result. Yesterday we finally bought our licenses, I will investigate further. Still, it's definetely a STEP-file issue, i rendered other PowerTranslator imports with Alpha 0.72 without any issues. Litttle spoiler: Vray renders the geometry without any issues ;). I am currently migrating my whole CAD animation workflow to Corona, it simply rocks - unbeatable in terms of tweaking time <> coffee breaks :)
(http://praeluceo.com/data/_uploaded/media/CORONA_brokenNormals.jpg)
CheerZ,
G.S.
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@ romullus
the export out of MoI is great. You can tell it to export as obj or fbx and further that it should just create n-gons instead of the typical tri mayhem you get via every other exporter or importer (or am I doing something wrong?). Plus you have a mostly closed mesh... which I always like.
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Indeed, MOI has a very exotic UI ;) But when you get used to it, you soon realize that you can get incredible results in the shortest amount of time. I too use it in everyday production, mostly as a chamfering / filleting tool.
The one particular issue with it, is when your input files get too large - like 100 mb or so. Then it takes a significant amount of time to open them, although eventually they open up successfully. Never tried rhino though, a lot of people told me that it's a great tool.
Now to the normals issue. For me the same thing, NDA, can't show too much here unfortunately.
But i digged up one comparison. On the left is Alpha 0.72, with the broken normals issue. 1.00.01 produced the same result. Yesterday we finally bought our licenses, I will investigate further. Still, it's definetely a STEP-file issue, i rendered other PowerTranslator imports with Alpha 0.72 without any issues. Litttle spoiler: Vray renders the geometry without any issues ;). I am currently migrating my whole CAD animation workflow to Corona, it simply rocks - unbeatable in terms of tweaking time <> coffee breaks :)
(http://praeluceo.com/data/_uploaded/media/CORONA_brokenNormals.jpg)
CheerZ,
G.S.
Hi Gabriel,
Looks like the same issue I had here and I get it from either Solidworks, Rhino or Alias geometry:-
https://forum.corona-renderer.com/index.php/topic,6170.0.html
It is the bug/poly conversion issue that Ondra had stated.
The problem is two fold.
As Ondra first pointed out to me, the problem areas are where the conversion creates extremely elongated polys (seems always to be when resolving trim edges) so I believe the problem may be resolved with better mesh conversion.
But yes, somehow other software (and as you flagged the Alpha 0.6 version) is managing to resolve these nasty conversions at render time.
Inspired by ignicapillus's comment on Rhino's advanced mesh settings I went back and experimented, seem to have resolved some of my problem geometry, so thanks!
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Hi GestaltDesign,
thanks for the info, and for the link to your thread :)!
I guess I'll just stick around with the Alpha 0.6 for this particular project, and hope that Ondra will be able to resolve the issue in future versions. Up till now neither do I process the STEP / IGES files myself, nor do i have any influence at what kind of data is being delivered, very unfortunate. But good to know the issue is known!
Thanks a lot again, and thank you Ondra for doing the incredible job out there :)
CheerZzz,
G.S.
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Npower is best of all I tested, sometimes you have to clean manually some "balls", they appear mostly because of CAD designer who didn't close or connect nurbs properly..
Sometimes SAT format understand better "unfinished" nurbs...
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Hi guys, I have the same problem here, Bild left is Vray Rendering and the right one is Corona.
I have imported the mash over nPower importer from one STEP Data Format. Like my next step to resolve the problem I have repair my STEP mash with Transmagic CAD Repair Tool but that doesn’t help me with my problem. Ondra please repair that, I love Corona , but without one clean tessellation solution I can not use it in my daily Job.
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Hi Monster,
The solution is to use Rhino and export geometry as .obj using the detailed mesh control option.
In the detailed mesh options you can limit edge length.
Limit the edge length (baring in mind relative object scale) and test using the preview option to eliminate long, elongated polygons which are the culprits.
Bare in mind the default 0 edge length means it is deactivated and allowing the potential for elongated polys.
Since using this approach and getting to know the mesh settings controls I have eliminated a whole host of import issues in Max.
Optimised obj meshes will also massively reduce file sizes in comparison to body objects, so win win.
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Hey, Monster
Could we use your image in our helpdesk as an example of this issue?
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Yes, no problem.
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Thanks!