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 From:  Michael Gibson
656.26 In reply to 656.18 
Hi Gent,

Thanks for testing in these different apps!

I certainly wish that more of them would behave better... :( I guess the problem is that these apps haven't really been tested with complex n-gons very well because there wasn't any particularly easy way to generate really complex n-gons coming from CAD data until now with MoI. Every other CAD program until now has generated only triangle and quad meshes. < Ugh! :)>

Hopefully more of these polygon apps will get fixed up over time as they get bug reports and there is more of a demand for processing complex n-gons.


> Silo:
>
> In Silo the actual mesh imports correctly, no problem with those planar
> polygons, but the smoothing is totally fubared, seems it doesn't import
> normal information correctly.

This one is particularly frustrating because they nailed the triangulation really well which is by far the most technically difficult part.

Reading the normals out of the file is far more simple, unless they just didn't make any provisions to have predefined normals in the app at all...

- Michael
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 From:  Michael Gibson
656.27 In reply to 656.21 
Hi Gent,

> So is it possible in the future for the obj export option to have a
> "divide larger than" value that is valid -only- for planar surfaces which
> would make it useful for such n-gons as you mentioned?

Yup, this makes sense and should be easy to add. I'll try to add it for the next beta which I want to put out this weekend.

I've also nearly got Adobe Illustrator file import working, that should be part of the next beta too.


> There wouldn't be much cases in MoI, where there would be complex
> concave n-gons that are -not- planar right?

Not often, because like you mention curved surfaces already get subdivided by the angle parameter.

You would have to have a surface that started out curved on one side and then flattened into a plane on the other side of the surface, with a complex trim on that flattened region.


It seems like XSI is pretty close to having full support, they've got all the ingredients they just need to tune up their triangulator a little bit. If you have a chance, you might want to submit a bug report to them (did you say you did already?) so that they have a good example that they can work with for debugging. If you can try to give them an .obj that has just the one complex polygon in it that doesn't work right.

- Michael
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 From:  jacobo3d
656.28 In reply to 656.25 
Hi Michael,

Thanks for your response.

I think it may be their OBJ importer problem. I think they wouldn't have
those problems reading LWO format. An example is, I never got a problem saving
an LWO object in Lightwave and reading it in modo, and viceversa.
Another example is what is shown in the screen captures below.
I've exported a simple object from MoI. The first capture shows that object
loaded in modo. I've loaded the same OBJ in XSI, wich read it OK, and then exported
it in LWO via Point Oven. The second capture shows that LWO loaded in modo.





In any case, I'm just guessing. I don't know how those object formats work internally.
What do you think?

EDIT: By the way.. how do you do to see the attached images in the message?
(sorry for such a stupid question :S)


Thanks!!

Jacobo.

EDITED: 9 Jun 2007 by JACOBO3D


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 From:  Michael Gibson
656.29 In reply to 656.28 
> In any case, I'm just guessing. I don't know how those object formats work internally.
> What do you think?

Hmm, well that's very interesting.

One of the things with OBJ is that it supports different attributes on each face. Like 2 faces can share a single 3d vertex point in common, but have different separate entries for uv coordinates or normals. MoI will normally export stuff like this in its OBJ files.

Possibly they do not internally support this type of different-attributes-per-face structure so they have to try to reconfigure the data and that has reconfiguration has some bugs in it.

Can you please try one experiment? Take that shape you show in your screenshot, and export it from MoI as an OBJ but set "Weld vertices along edges" to _off_ (not checked), and see if the OBJ with that setting works better.

When you turn off welding, it will make an OBJ with a somewhat more simple structure, there won't be faces that share a common 3d point but have a different uv for example - either everything (3d point, uv point and normal) will be shared or not. It should be closer to the structure that they seem to use.

Does that seem to work better than before or not?


> EDIT: By the way.. how do you do to see the attached images in the message?

You have to type a little HTML code in your message if you want your attachment to show up directly in your message, there are some details here: http://moi3d.com/forum/index.php?webtag=MOI&msg=68.118

- Michael
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 From:  jacobo3d
656.30 In reply to 656.29 
Hi,

I've tested what you suggested, and here's the result.
'Angle' value is 12, and 'Weld vertices along axes' is ON:



Keeping 'Angle' at 12, but turning 'Weld vertices along axes' OFF:



When I increase the resolution and n-gons size ('Angle' is 8), this is
what happens. 'Weld vertices along axes' is OFF:



The same but 'Weld vertices along axes' is ON now:




And here's a problem I've found editing this object in MoI. As you can
see in the images, I've just selected that edge, and then apply 'Fillet'.
And that's what happens to the surface:



I've attached the IGES by the way, so you can test it (housing_shf_60_l.rar).


Thanks!!

Jacobo.

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 From:  Michael Gibson
656.31 In reply to 656.30 
I guess there just isn't much hope for the Modo OBJ reader, it just does not seem to be able to handle N-gons well. The denser and more complex they get, the more it gets messed up.

Modo does seem to be able to handle n-gons from LWO files a lot better for some reason (less bugs in that particular code I guess). I decided to test that by writing a new LWO exporter. Even when sending the exact same polygons, it works well with LWO and not well with OBJ. That seems pretty weird to me but that seems to be the case.

It's still not perfect even with LWO, I saw a couple of triangulation errors still on certain n-gons, but it is more like 2 errors instead of 100 errors. So it seems like that should help out a lot.

LWO does not support vertex normals for smoothing though, so you can't get the really accurate shading as Gent showed above. It seems like that style of shading is just not supported in Modo or LW. So it may not be possible to get quite as high of render quality as Cinema4D or XSI that do support the accurate vertex normals.

- Michael
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 From:  WillBellJr
656.32 
Thanks Michael for looking into the import issues with the LWO codebase - Lightwave is my main app and being able to get MOI objects into it (even if a roundabout method is required) is important for speeding up my modeling workflow (through the use of MOI.)

-Will
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 From:  jacobo3d
656.33 In reply to 656.31 
Hi Michael,

First of all, thanks a lot for the LWO exporter! That is just great!

It's a shame what happens with some OBJ importers. After test
with different objects in different applications, it seems like the only
ones that import the OBJ right are Maya and Cinema4D.
Even converter programs like Polytrans or Deep Exploration have
problems.

It's funny what modo does with OBJs, because I've been trying to export
some objects with some kind of complex n-gons from modo to OBJ, and
then it imports that OBJ with no problems. But when you try to import
that OBJ in another different application (like Lightwave) the mesh is
messed up.
And the same things seems to happen to Lightwave if you export an
OBJ from it. It reads the object OK, but not other apps (like modo).

Again, thanks!! I can't wait to try the new beta (is the LWO exporter going
to be included on it?).

Jacobo.
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 From:  Michael Gibson
656.34 In reply to 656.33 
Hi Jacobo,

> Again, thanks!! I can't wait to try the new beta (is the LWO exporter going
> to be included on it?).

You're welcome, yes I will include the LWO exporter in the next beta, it's going to probably delay the beta by a couple of days though. Probably the bugs that you reported earlier (the filleted box and that other fillet one) will have to wait until the next one after, but I figured that you would rather have LWO as a higher priority anyway.

Originally I wanted to focus just on OBJ because it is the most flexible format, it pretty much supports everything - n-gons, vertex normals, smoothing groups, per-face attributes... It would be really nice if other applications would provide OBJ importers that worked.

- Michael
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 From:  Michael Gibson
656.35 In reply to 656.32 
Hi Will,

> Lightwave is my main app and being able to get MOI objects into it
> (even if a roundabout method is required) is important for speeding
> up my modeling workflow (through the use of MOI.)

The next beta with direct LWO export should make it much less roundabout. There still may be a few issues though, you may need to manually split a few n-gons that LightWave doesn't triangulate successfully but hopefully these should be small in number.

- Michael
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 From:  Matt Gorner (MATT)
656.36 In reply to 656.34 
Wow, next build will have a LWO exporter?

Michael that is great news!!!

We use SolidWorks at work, and used to translate to LightWave using STL. Problem was, being STL it triangulates everything, even if a quads or n-gons would be fine. The fact that MOI imports IGES files beautifully and can mesh to quads / triangles or n-gons meant mesh sizes (and poly flow) were great improved.

In previous versions of MOI I too have the polygon normal flipping issues, even joining surfaces in MOI didn't solve it.

The first attached image shows the problem I had.

The latest build seems to be much better, as you can see from the second attachment

But I must thank you for an excellent piece of software, it has transformed how we import from SolidWorks to LightWave.

Out of interest, what are the chances of being able to mesh to ALL quads? Or is that not possible in order to acheive a good mesh?

Best regards
Matt Gorner
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 From:  Michael Gibson
656.37 In reply to 656.36 
Hi Matt,

> Wow, next build will have a LWO exporter?

Yup, I had not originally planned on doing this for v1, but it seems to be the only way to get n-gon polygon data into LightWave or Modo fairly reliably.

I'm glad MoI is useful to you for transferring from SolidWorks to LightWave!


> Out of interest, what are the chances of being able to mesh to ALL quads? Or
> is that not possible in order to acheive a good mesh?

It's theoretically possible, but it would require a substantially different approach to the meshing process.

The underlying NURBS surfaces are inherently quad based, so meshing just a plain surface generates quads nicely. The problem is with trimmed-away areas. Trim curves on surfaces generally go in any direction, they don't necessarily follow the same quad flow-lines of the surface.

So it's quite difficult to generate all quads with trimmed surface data, it just doesn't come very naturally, it would require a lot of complex code to try and squeeze little quads around trimming boundaries. I won't be able to dig into something that complex anytime too soon...

- Michael
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 From:  WillBellJr
656.38 
Yes, exporting an all-quad mesh would be the holy-grail of polygon exports - something I wouldn't dare try to ask for - LOL (Just thinking of Indiana Jones with all the mess he went though over the Holy Grail! I don't need skeletons flying around the room whenever I'm performing a MOI export into Lightwave! :-p )

It's nice to see so many LW'ers around here!

I'd like to say again thanks Michael for the time you're putting in to help us out. MOI is really nice with what it does and I really want to use it within my workflow - this will help a lot.

THANKS!

-Will
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 From:  Matt Gorner (MATT)
656.39 In reply to 656.37 
No problem Michael! Even with all quads, MOI still produces the best meshes out of any converter I've seen.

I just tested an import of a more complex object, I'm still getting polys flipped, despite joining surfaces, see attached.

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 From:  Michael Gibson
656.40 In reply to 656.39 
> I just tested an import of a more complex object, I'm still getting polys
> flipped, despite joining surfaces, see attached.

Hi Matt, was this when using an OBJ import into LightWave?

Their OBJ importer seems to be pretty buggy when trying to deal with complex N-Gons. You might try submitting that OBJ file to them so they can fix it up.

But that's why I'm doing the LWO format, because it doesn't seem to be as buggy as their OBJ importer.

In just a couple of days you'll be able to try and and see if it works better for getting N-Gons into LightWave.

- Michael
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 From:  jacobo3d
656.41 In reply to 656.34 
Hi Michael,

>You're welcome, yes I will include the LWO exporter in the next beta, it's going to probably delay the beta by a couple of days >though. Probably the bugs that you reported earlier (the filleted box and that other fillet one) will have to wait until the next one >after, but I figured that you would rather have LWO as a higher priority anyway.

Those are REALLY great news Michael. And for sure LWO is a higher priority for me, so I really appreciate
you're including that option in the next Moi beta. Seriously, thank you very much.

I agree with that; it's a shame that other 3D apps OBJ importers are not as good as they should. I can't understand how
today there's no full support for a so extended format. I think that formats like OBJ (for polygonal geometry), or MDD
(for vertex animation information), etc... should be full supported by any 3D application. But anyway... it's just a
thought... :O)

Again, I can't stop saying thank you for the LWO exporter, and for the great feedback you have with the users.
I hope all the issues we suggested over here help you in some way to make Moi a better application, instead of
driving you crazy :O)).

Jacobo.
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 From:  Matt Gorner (MATT)
656.42 In reply to 656.40 
Yes it was an OBJ set to n-gons out of MOI. It also comes in that way if I set MOI to mesh with triangles only, so it's not just n-gons or quads that it freaks out on.

What's odd, is that it works fine for some objects and not others. I think it must get confused with objects that have 'insides' (if that makes sense!)

Look forward to testing the LWO exporter. I have a rendering job to do at the moment with CAD files coming from CATIA, would be great to have it for that!

:D
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 From:  Michael Gibson
656.43 In reply to 656.42 
Ok, can you guys test the attached .lwo file to see if it will go into Modo and/or LightWave ok? This one was produced by the new LWO export.

There are still various problems you will probably run into, there are some limitations in LWO / LightWave / Modo that cause problems with certain types of shapes, it's the same problem Gent was showing here: http://moi3d.com/forum/index.php?webtag=MOI&msg=656.16 - LWO does not have any way to specify the vertex normal smoothing information, instead it tries to average surrounding faces to create a shading normal, this will cause problems with some types of shapes.

If you run into these shading problems, you may want to turn "Weld vertices along edges" to OFF when exporting, that will create crisper style edges and avoid shading "leaks" between different surfaces.

When researching this, I saw this post: http://forums.luxology.com/discussion/topic.aspx?id=17281 which says that the next version of Modo will support vertex normals, so things might get better then.

- Michael
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 From:  jacobo3d
656.44 In reply to 656.43 
It's imported perfectly in LW and modo:





The smoothing seems to be OK in both of them... did you have to turn "Weld vertices along edges" OFF for
this example?
By the way... do you think you'll be able to include for this beta the option to use "Divide larger than" only for n-gons?


Great job!! Thanks for that!
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 From:  Michael Gibson
656.45 In reply to 656.44 
Great! Thanks for testing that! I've got the demo version of Modo over here but not LightWave right now.

I forgot to mention that this version also was done with an angle of 8, which didn't seem to work well in your OBJ test above.


> did you have to turn "Weld vertices along edges" OFF for this example?

No, not in this case, this one had welding on so there is only a single point shared between each polygon. If there are mostly fairly sharp corners between pieces it will tend to be ok.

When there are smooth pieces next to longer flat pieces, that's when you'll tend to get more shading problems. The way LightWave/Modo's shading currently works, a small somewhat angled polygon can have a pretty big effect on the shading of a longer flatter polygon next to it.

I'm pretty sure you'll run into some problems with that. Your main tools to try and reduce it will be either no welding, or try to divide things into somewhat more equally sized and angled pieces. Also if you have a longer polygon with a shading error kind of stretching out along it, you might also try manually dividing the n-gon into 2 polygons with one piece being short towards the end where the shading problem is coming from. That will tend to contain the shading problem more in the new smaller piece.

Also sometimes the real-time display will exaggerate the errors even more. When you see them try doing a full rendering, it may not be really quite as bad as it looks at first.


> do you think you'll be able to include for this beta the option
> to use "Divide larger than" only for n-gons?

Only for planar surfaces you mean? Yup, I've finished this, the setting next to "Divide larger than" is now a drop-down instead of a checkbox, the choices are "Curved" (means apply the divide only to curved surfaces, not to planes), "Planes" (apply only to planes), or "All" (apply to everything).


Now I've just got to get back and finish up a couple of things that I put aside when I sidetracked to do the LWO stuff...

- Michael
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