How do you tell that there is a seam? Is it lack of continuity?

I added some isocurves, did some trims, and blended surface edges.
Do not know if this makes any difference. Just practicing.

Hi Sneather..welcome aboard :

when you open the export menu' in Moi try to control your model just in shaded mode (without showing polygons) this is how will render later in your application

I opened your model and try to export it,you can see a surface not joined properly,maybe that surface was modeled after main cylinder(see the mesh completely different of the rest)






so i deleted that patch and rebuild a new one by sweep:
blue=section
green rails
using your arc to cut the new patch (white)
this is a quick method just to show you the problem,sweep don't give a continuity with the main surface



then joined new patch with the main surface:no more cracks



you have other surfaces not correctely joined...



so i exported in C4D:you can see same problems



my suggestion is: ask to your customer a file in STEP format if it's possible and before exporting have a look in shaded moded,rotate your model,have a zoom to see closely...it not depends by Moi at all !

Hi sneather, definitely Joining is the key thing for avoiding those kinds of cracks - if 2 surfaces are meshed totally independent from one another it's quite easy for them to have different vertex structures along their edges and that shows up as exactly those kinds of cracks that you are showing. When edges are joined to one another MoI's mesher will do extra work to ensure a unified "water tight" mesh structure along those edges, so you have to get things joined in order to avoid that problem.

There is a script which will highlight all unjoined edges, it can be useful to see areas of a model that might need repair. To set it up, go to Options > Shortcut keys and push the Add button to add in a new entry at the top of the list. In the key column put in N and for the command column paste in the following:

script: /* Highlight naked edges */ var gd = moi.geometryDatabase; gd.deselectAll(); var breps = gd.getObjects().getBreps(); for ( var i = 0; i < breps.length; ++i ) breps.item(i).getNakedEdges().setProperty( 'selected', true );


Then after that if you push N any naked (unjoined) edges in the model will highlight, it can help you to zero in on joining issues.


> Finally, the offending seams look to be perfectly aligned inside MoI. The surfaces seem to meet up at
> precisely the same poly-lines. So, it's not like they are (obviously) further than that .005 threshold
> number for "join" to work.

It's often difficult to eyeball small distances - I was able to use the "CrvDeviation" command in Rhino to get a numeric value and the maximum gap between those edges you are asking about is 0.02 units, so it's quite a ways above the join tolerance.

You can't easily see the gap from some directions, in this case you would see it most easily by looking downwards on it, here is a screenshot to show you:





In the typical way things work a 0.02 unit gap is pretty large, the model may have been fairly roughly modeled in that area and was probably not originally joined together in its originating application either.


You could try a trick of shrinking everything down in size - when you scale models down gap sizes will also shrink as well, so you could try using Edit > Separate and then scale downwards by 1/10 in size (select all and then run Transform > Scale, type in 0 and push enter to specify 0,0,0 as the scaling origin, and then type in 0.1 and push enter for the scale factor) and then do the join. That can sometimes by an easy solution. Otherwise if some areas of the model are of particularly poor quality they may need to be reconstructed.


In your case here it looks like doing the scale down will get a bunch more things joined, so try that since it is the easiest.


Basically if the geometry in the actual file is of somewhat low or rough quality that can make things more difficult for you when trying to process it. You won't generally get nice results in an automatic fashion from poor quality geometry, you'll likely need to do some repairs and fix up modeling work as well.

Hope this helps!

- Michael

Thank you ALL so much for the terrific, comprehensive and timely assistance.
This also gives me great confidence (being a new user) that this is also a great forum for future stumbling blocks.

First, I will practice implementing and experimenting with all of your suggestions. I love the idea of that special script to help highlight the naked edges. Although, that brings me to a question about those kinds of things. Is there an extensive (hidden?) library of such useful commands that I need to memorize, or add to other quick keys? My limited use of Rhino proved that I needed to know many of those commands in order to really use the program to its strengths.

Second, it will be my goal, and hopefully should not be an issue to get STEP files from my clients. This test IGES file was just something I had sitting around from a year ago, for a product that never made it to market, so I never commenced work on it. I just wanted to test out that file structure, and learn some more about MoI. In regards to the asset file format. My understanding is that STEP is the best format, but are there any specific settings of which the client needs to be aware, when they export from their CAD systems (Pro/E, Solidworks, etc.)? I would assume, depending on what they are using, the BEST possible format, would actually be .3dm. But I think that only applies to Rhino and MoI, or am I wrong there? Can Pro/E or Solidworks also write to that common format?

Thank you all, again!

Hi sneather,

> Is there an extensive (hidden?) library of such useful commands that I need to memorize, or add to other quick keys?

There is a library of them collected here: http://kyticka.webzdarma.cz/3d/moi/ - the main place to find links to such things is on the resources section of the main web site.

But probably that show naked edges one would be the most useful one that you will want to have set up.


> My understanding is that STEP is the best format, but are there any specific settings of which
> the client needs to be aware, when they export from their CAD systems (Pro/E, Solidworks, etc.)?

Most of the time STEP is preferred, but unfortunately it's still a complex format and still needs to have trim curves processed in different ways and with any kind of fairly complex geometry processing there is some potential for problems. IGES can also have it's own set of issues as well but they tend to be somewhat different in nature so I'd really recommend asking for both STEP and IGES formats both instead of only one single format.

There shouldn't be any special settings needed when your clients export, just default settings should be fine.


> I would assume, depending on what they are using, the BEST possible format, would actually be .3dm.
> But I think that only applies to Rhino and MoI, or am I wrong there? Can Pro/E or Solidworks also write
> to that common format?

I think that Solidworks can read .3dm but not write one, and I'm not sure about Pro/E. So it may not be an option. It probably wouldn't be a bad idea to ask about though, because yes most generally 3DM format involves the least amount of extra complex processing that needs to be done to things on import into MoI so that helps make things more robust.

- Michael

Thank you, Michael.

I'll talk to the designers/engineers and see what they say. I'll also delicately ask if they can make sure (as much as possible) that I get parts with "water-tight" seams, whenever possible.

Hello,

Getting watertight models from clients might be tough sometimes. I know Spaceclaim in my experience does a good job of finding those problems and fixing them. They seem to have focused on model repair as one of their strengths. It's a little more involved workflow IMO, and not as inexpensive as MoI. I find myself starting in MoI and then moving to Rhino or SCE to finish some operations that can't currently be done in MoI. It doesn't hurt that the MoI community is so quick to help.