Meshing problem with g2 blended surface.

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 From:  PaQ
2091.1 
Hello everyone,

I'm trying to apply an other technic than usual for building this ship, using massively G2 blending.
In fact I was quite please with the results so far, I was able to keep some 'hard' edges from the original design,
but I still have nice specular on edges without any fillets.




However, I've tried a quick meshing tool preview, and I discover some strange lines in my model ...


Which in fact were just holes Oo


The only way to correct it was to use the 'divide larger than' setting, until I have a vertical section in the artefact area


But doing that will give me a really too heavy model, and it's not a viable solution for this project.

2 or 3 surfaces were build with rhino network tool (for continuity reason), but it's actually surfaces building inside moi that
show the problem.

I have attached a part of the model, troubles are somehere in the yellow selected surfaces (need to zoom quite close in the
meshing preview)

EDITED: 4 Dec 2015 by PAQ

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 From:  George (GKSL4)
2091.2 In reply to 2091.1 
Please,

Its very hard to read this images!

Try to keep it smaller
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 From:  PaQ
2091.3 
Hi Michael,

I'm trying to play around with this meshing problem.



Trouble only happend here if:

a,b,c are G2 witn a bulge of 0.25 (for ex. 0.3 doesn't show any problems)
1 and 2 must be G2 too (I only tried with a bulge of 1 so far) , because in G1 there are no problems.



Increasing the mesh angle inscrease the number of artefacts.
It happends whathever the output are tris, quads-tris, or ngone

Not sure if it's helpfull for you.

EDITED: 4 Dec 2015 by PAQ

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 From:  Michael Gibson
2091.4 In reply to 2091.3 
Hi PaQ, thanks for the examples, I'm looking at it now.

It definitely looks like a bug in the mesher, it's probably triggered by the structure of these surfaces, looks like they have a very similar UV structure but just very slightly off from one another.

I'll see what I can do to fix it up.

- Michael
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 From:  Michael Gibson
2091.5 In reply to 2091.3 
Hi PaQ - it looks like an error in the triangulator.

If you export with N-gons the actual N-gon saved to the file does not seem to have that gap in it when you load it into another program.

I'll be working on tracking down that triangulator bug shortly here, but in the meantime I think if you save your file as N-gons you should find that your data is actually fine.

- Michael
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 From:  PaQ
2091.6 In reply to 2091.5 
Allright Michael, if I can export it in ngone it's allready a good news.
I still have lot of work to do on this model, so I'll do the final export monday evening or so.

Thanks for you help !

EDITED: 17 Oct 2008 by PAQ

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 From:  Michael Gibson
2091.7 In reply to 2091.6 
Hi PaQ,

re: Meshing problem with blended surfaces

This was a tough one! But I have fixed it up for the next beta.

It actually was not a bug in the triangulator after all. The n-gons that you export do not have a hole there exactly but they do have a very small folded over area, kind of like this:



That's shown slightly separated there, the actual n-gon has a kind of "back tracking" overlapping part on it. MoI's triangulator will try to not make triangles that go in the wrong direction so they don't try to fill in that part that folds back, that's why there was a tiny hole in the display there.

The actual bug is a pretty subtle thing involving tolerances and accuracy of dicing up curves into lines for sampling for various calculations. I have tuned these areas to solve this problem and make these processes work better, but please let me know if you run across this kind of thing again in the future after the next beta is out.

- Michael
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 From:  Frenchy Pilou (PILOU)
2091.8 
@PaQ : vous modélisez tout de même de manière désinvolte! :D :)

Cheeky casual nonchalant glib modeling! :D :)
---
Pilou
Is beautiful that please without concept!
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 From:  Michael Gibson
2091.9 In reply to 2091.7 
Additionally the fix for this, plus one other tune-up improves making simple all-quad meshes for surfaces of revolution.

In the next beta the unwanted n-gons that Tony got in this message:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2000.4
are now all quads instead.

It also used to be possible to occasionally get an n-gon instead of a quad in the seam area of a surface of revolution, that's also fixed, those will be all quads in those areas now.

- Michael
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 From:  PaQ
2091.10 In reply to 2091.9 
Thanks a lot for the fix, of course I'll report any other bug I found in the next release.

I'll try to rebuild this model with the next beta, I wasn't able to finish the model in nurbs (nothing to do with the export bug), but
the method I used wasn't good ... So I switch to modo for this one.



I really don't know which approch I have to used for something like that. I've tried to build the model in full flat (planar) face first, but then can't fillet anything.
It's strange how simple model at first can be hard to build ...

EDITED: 28 Nov 2014 by PAQ

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 From:  PaQ
2091.11 In reply to 2091.10 
@Pilou, I don't know how to understand the remark :P
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 From:  Frenchy Pilou (PILOU)
2091.12 In reply to 2091.11 
@ Paq: simple galéjade :)

EDITED: 24 Oct 2008 by PILOU

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 From:  PaQ
2091.13 In reply to 2091.12 
@Pilou Bah au moins j'aurai appris un mot ce soir :P sauf qu'apparemment cela s'écrit galéjade :P
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 From:  Frenchy Pilou (PILOU)
2091.14 In reply to 2091.13 
hihi mais non un mirage ;)
---
Pilou
Is beautiful that please without concept!
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 From:  PaQ
2091.15 In reply to 2091.14 
ca c'est pas du jeu !
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 From:  Frenchy Pilou (PILOU)
2091.16 In reply to 2091.15 
;)
---
Pilou
Is beautiful that please without concept!
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 From:  Denis (SPACELAND)
2091.17 In reply to 2091.16 
Moi aussi je viens d'apprendre un autre mot.

Mais j'avais compris la remarque de Pilou.

:)
Cold
| Adobe Photoshop CS | Corel CorelDraw Grahics Suite X3 | Daz 3D Bryce 5.5, Carrara 6 Pro, Hexagon 2.5 | Maxon Cinema 4D R8.2 | Moi 3D |

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 From:  PaQ
2091.18 In reply to 2091.17 
On va finir par se faire ejecter dans la section frenchy !
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