From: NotSolidEnuf (WMEPARKER)
Hi All,
I did a quick search to see if this has come up before, and didn't find anything, but it could just be my search was wrong. I have two files with complex models, both are hundreds of surfaces. When you select the model, it does not say it is a solid, it says it is a "joined surface". However, if you use the select open curve function, the "N" key as it is known, no objects are highlighted, and no count of them shows in the status window. If you try to highlight solids, none come up, and the status window should show that when the model is selected. Is there any other diagnostic I can use to find out why MOI isn't calling this a solid?
Thanking you in advance,
Bill
From: Michael Gibson
Hi Bill, when this happens it means that there was some problem in setting up regions. Once you have no naked edges, then what is supposed to happen is there are 2 region structures formed, one for the "infinite region" of all volume on the outside of the object and then another region for the interior solid volume area.
An object will only read as solid if it has at least 2 regions (more than 2 means having internal void cavities as well), and no naked or non-manifold edges.
So if there was some error in generating the regions you could end up with no naked edges but not registering as a "solid". This is pretty rare though.
It may be that you have some area of the model that has either a degenerate trimming boundary or a degnerate tiny surface sliver either of which can mess up face traversal when it comes to volume type calculations.
The easiest thing to try is to select your models and use Edit > Separate to break it into individual surfaces and then follow that with a Join, that will try to force region calculation again.
If you do not have any naked edges it could be possible that your mode will actually be ok anyway, but it's somewhat likely that if regions can't be calculated that there is some problematic area of geometry like some kind of self intersection or degenerate boundaries somewhere.
- Michael
From: NotSolidEnuf (WMEPARKER)
Hi Michael,
Thanks for replying so quickly. Actually, I have more symptoms. I did try to separate, then join. Same result. When I exported the model to a STEP file, then opened it, it was not joined, all of the surfaces were separate. I don't know if that tells you anything. I guess I will try joining everything together again surface by surface.
Best,
Bill
From: Michael Gibson
Hi Bill, in the STEP import library if it runs into some errors figuring out the joining information in there, it will just try to grab all the surfaces individually.
> I guess I will try joining everything together again surface by surface.
That's the main way to work on this kind of problem, at some point you'll probably find an area that may have some badly formed surfaces that may need to have some reconstruction.
- Michael
From: BurrMan
Take note of the overall size of your model, then scale it up or down by 10, then do the seperate/join on it, to locate the problem area.
From: NotSolidEnuf (WMEPARKER)
I now have files that are showing as solids. This is a major step forward. However, if I try to export to STEP, it still separates the surfaces individually. These are hundreds of surfaces in these models. Is there no way to make this work? If I have an MOI file that shows as a solid, is it going to show me the problems that are causing the export to STEP to fail?
From: Michael Gibson
Hi Bill,
> However, if I try to export to STEP, it still separates the
> surfaces individually.
Have you tried importing the STEP file into a different program? If you're exporting to STEP using MoI and then importing back into MoI also, it's difficult to know whether the separation is happening at export time or at import time.
> If I have an MOI file that shows as a solid, is it going to show
> me the problems that are causing the export to STEP to fail?
No, there isn't anything built into the STEP exporter that would give back specific information like that.
- Michael
From: ed17 (ED17ES)
Taking the way to perfection, thats how every piece of software should be. Great work there!
From: NotSolidEnuf (WMEPARKER)
Has anyone tried the 3dm import function from Rhino to Solidworks on MOI 3dm files? Is this an option, because this is what I am trying to achieve by exporting to STEP.
Incidentally, Michael, the problem must be on export because the SolidWorks guy is opening the STEP files and getting individual surfaces.
From: BurrMan
"""""""""""the problem must be on export because the SolidWorks guy is opening the STEP files and getting individual surfaces."""""""""""
If you have a "solid" in MoI and export the STEP file, what happens if you just import the STEP file "back into MoI" right after export?
If you export "IGES (surfaces)" then import to solidworks and attempt to Join, solidworks will have many options to show you problem areas. Or, you can attach your file here so it can be looked at. If it's proprietary or something, a private email to Michael can help to handle that.
From: Michael Gibson
Hi Bill,
> Has anyone tried the 3dm import function from Rhino to Solidworks
> on MOI 3dm files? Is this an option, because this is what I am trying
> to achieve by exporting to STEP.
Yeah, that's definitely worth trying - I'd recommend trying all of STEP, 3DM and IGES as well to see if one of those works better for your particular case.
Also it's very normal for IGES files to contain individual surfaces in them so most likely SolidWorks will go through a joining process itself if you use that format to transfer stuff over.
- Michael
