I'm wondering whether anyone has any relevant experience, working with files exported out of Autodesk Alias?
I'm working on a project now, and the designer is creating a product using Alias. I've asked that he export a stitched STEP file, but it just doesn't seem to behave as well inside MOI as I would hope. The initial surface quality is poor, although, I've been able to stitch a number of those problem seams. But I'm also having difficulties with adding chamfers (for instance) to some seemingly clean edges. They just don't take. I'll post a sample scene shortly, but I wanted to get a quick post here, to see if there are any immediate suggestions for working with Alias model files.

Thanks!

Hi sneather, there isn't really anything in particular that comes to mind.. Maybe you might try having them export to IGES format instead and then let MoI join it at import time instead of having Alias try to join things together itself. A lot of times Alias models I think are just surfaces and not really created as joined together solids to begin with. If it's been created as a whole bunch of separate surfaces that do not touch each other very tightly along their common edges then you just won't really be able to automatically get a finished solid from something like that...

- Michael

Hi Michael,

Thanks. I think you're right about the principal design method in Alias, being predominantly sheet-based. I certainly know, from a few earlier attempts with the same model, that there were some odd extending surfaces, and some which also totally intersected. Knowing those would really give MOI fits, I asked the designer to trim and clean up as many of those as possible. But it seems like the next logical step would be to try IGES instead of STEP. The downside there, if I'm not mistaken, is that it's potentially a much more complicated process - whereby I'll have to group all the proper surfaces together. In other words, the layers or object groups in their original Alias file won't make it into MOI, like the way a STEP file works. Right?

Cheers!

Hi sneather, IGES does have the concept of a "Level" which is basically the same as a layer. I don't know for sure that Alias writes that information out to the IGES file but if it does then the layer grouping should come through too with IGES format. You'll lose the specific name, they'll be named things like "Level 1", "Level 2", etc... in MoI because an IGES level is just a number and not a text name though.

But it's also possible that the way trim curves work in IGES will more closely match how Alias structures them itself so if you're running into problems with things trimmed incorrectly that may possibly be lessened in this particular circumstance using IGES.

- Michael

But also, if the model data is not already set up to have surfaces that touch edge to edge in a clean manner, then it's just not ready to be built directly into a solid (by a push button method) no matter what format you use...

- Michael

Okay. Thanks. On Monday, I'll ask the Alias designer to try out some IGES exports.
I may have to try that for the more complicated sheet issues, then use STEP for the simpler parts.

Regarding the actual state of the model, itself. Yes, I've already had the designer go back and clean up some of the more obvious surface issues. Most of those (once joined in MOI) seem to be free of naked edges. But again, oddly, some of those seemingly clean edges still won't hold a bevel. But per your previous post, I'll see whether IGES exports might help at all.

Thanks!

Hi sneather,

> But again, oddly, some of those seemingly clean edges still won't hold a bevel.

I'd need to see the actual model in order to try and give you any information on this part.

- Michael

Update:

I had the Alias designer try sending me an .igs file. I couldn't open it in either the current version of MOI, nor the v3 Beta I have. No warnings, simply nothing imports. Just to make sure that the file wasn't corrupted, I tried Rhino, and it came in perfectly.
Any ideas? Are the IGES issues with MOI? Or are there export steps needed to write the correct file from Alias?

Thanks.

Hi sneather, I'm not aware of any particular issues with MoI's IGES importer. I would need to see the particular IGES file to be able to give you any good information about what's going on there. If you are able to, please send it to me at moi@moi3d.com

There are a few different ways that it is possible to store things in IGES files, I guess that probably the method used for that file is not supported by MoI's IGES reader.

If they have some options they can change at export time, ask them to set it to export "Type 144" trimmed surfaces and see if that works any better.

- Michael

I'll have to see what I can do about assembling the IGES file. But even at best, it's still (obviously) a much bigger pain to work with - as compared to STEP, because the lack of naming structure and the sheer number of pieces to re-join.

In the meanwhile, I was at least able to get the Alias designer to send me a comprehensive screen grab of the potential export settings for STEP files, from Alias. Do any of these stand out as critical in regards to how MOI might best prefer?

Thanks!

Hi sneather, probably you'd want Trim curves with the "Model space" setting.

I'm not 100% sure what some of those other settings mean exactly like what in particular Alias means by a "hybrid model", that's some kind of terminology specific to Alias and not particularly a general STEP specific thing as far as I know.

Protocol type AP203 versus AP214 - either should work ok, but the 203 type contains only geometry and not any names or color information, that's stuff that has been added in by the 214 variant.

- Michael

Great. Thank you for taking the time to review these screen grabs, Michael.
I'll ask the designer to try out what you recommended, and see whether any of that helps (at least a little).

He did ask me whether I could handle WIRE format, as supposedly that's rather native for Alias. But I've never seen that as an import function for any software app I use. That could be some of the trouble, in that Alias really does work within its own proprietary world, and trying to get functionality with divergent apps might not be as easy, compared with other CAD systems.

Here you go sneather:

http://www.autodesk.com/techpubs/aliasstudio/2010/index.html?url=WS1a9193826455f5ff-54f556ca1166ac9ee9e-7a77.htm,topicNumber=d0e178529

Link this to your designer.

If the model is a "solid" (as in MoI solid) the he will use the G5brep solid option.

So there are some other options, but they really depend on what's being exported. The designer will know whether it's "surfaces" or "solids" and whatnot. You'll want to avoid wires. You would have to rebuild all the surfaces, and would loose what Alias is doing with regard to surface continuity and such.......

The hybrid model thing is exporting out "all things alias", and can cause issues.

Hi sneather,

> He did ask me whether I could handle WIRE format, as supposedly that's rather native for Alias.

Yeah it's the native file format for Alias. It's not very often supported by other software, I don't think that it's a publicly documented file format.

I seem to vaguely remember something with PolyTrans being able to do it:
http://www.okino.com/tutorials/gplugs_tutorial.htm

It's more likely that IGES or STEP would be the way to go.

- Michael

Thank you!

Thanks, Michael.

ALso, just as more added info, it may be a communication error with regard to "Wires". meaning, not necessarily the "dot wire format", but wires as in edges. Alias' export can be solids, surfaces or wires, with several options for each (the hybrid is all of those things and options) and, Alias kind of does all it's surfacing WITH wires. I don't think those would work for export though, because alias will be carrying all sorts of surface continuity information along with the wires, so MoI running sweep on 4 closed edges from alias will not produce the same surface with "edge directions" regarding tangencies.

lol