MoI to Modo - problem with anisotropic reflections?

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 From:  jbshorty
1690.1 
Hi Michael. I have been noticing there is a problem when exporting LWO, then rendering in Modo using anisotropy. Take a look at this attached picture. The MoI mesh has a "banded" effect, revealing the faces in the mesh. But the same object exported from Rhino via OBJ renders with good anisotropy. Both objects have similar UV layouts for the top face, yet very different rendering results. Any idea what might cause this, or how to resolve it? I doubt there is anything i can do in Modo to fix this...

Thanks,
jonah
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 From:  Michael Gibson
1690.2 In reply to 1690.1 
Hi Jonah, I'm not really sure - maybe it has something to do with the default material that MoI writes into the .lwo file.

What happens when you export OBJ from MoI into Modo - do you get a proper result from that or does it look the same as the LWO export?

If you get the same messed up result, that would help point me towards looking at the geometry and UV coordinates, and otherwise at more LWO specific stuff.

Also, can you see what happens when you export LWO from Rhino as well?

- Michael
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 From:  TwinSnakes
1690.3 In reply to 1690.1 
Its the UV's. Modo's anisotropy is UV map based. You can fix this 2 ways:

#1 - Make a very tiny hole in your caps (top/bottom) of the cylinder, this will turn the triangles into quads. The hole method is what Lux used when they first demo'd this feature in Modo. Because it lets your UV map (quads) match your model (quads).

OR

#2 - Make sure your the verts at the center of the cap are at the top of the UV map, and make sure the verts at the edges are at the bottom of the UV map.

-TS-
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 From:  jbshorty
1690.4 
Thanks TS. That might be a good solution for examples as the one i posted(although I'd rather not punch a hole in my mesh). But I've also seen this problem on rectangular surfaces as well. It's funny because Rhino UV layouts and MoI UV layouts are basically the same if you don't "pack textures" when exporting from Rhino. But there is a surprising difference in the way that Modo handles them. Perhaps some difference in the vertex normal maps? I haven't had time to try different solutions. I will do some experimenting when i can...

jonah
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 From:  Michael Gibson
1690.5 In reply to 1690.4 
Hi Jonah, I guess you might want to try turning "Weld vertices along edges" on or off - there is a slightly different mechanism used for both texture and normal maps in the LWO file depending on whether welding is enabled or not.

One for a style where there is one UV or normal stored for each vertex - this is used if welding is turned off. But if welding is turned on then it uses a different way to specify them that lets you specify different information for each face instead of only per vertex - this is for the spots where you have one 3D vertex in common but different normals and UV coordinates on different faces that hook into that vertex.

Maybe that has something to do with it...

- Michael
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 From:  jbshorty
1690.6 In reply to 1690.5 
Thanks Michael. I always export with welding off. So I'll try next time with welding on and see what happens...

jonah
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 From:  Michael Gibson
1690.7 In reply to 1690.6 
It really is not supposed to make any difference but it does cause different kinds of "chunks" to be used in the LWO file to store the data.
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 From:  manz
1690.8 
With respect, I do not actually follow, or should I say understand this "Problem"

The models I export from MoI then import into another application for rendering, I use that renderer(application) to make needed UV. Why is there/ should there be a need for a model to have specific/defined UV etc when imported, should not the application importing that object have the ability to make (be it auto or manual) correct settings for render?

Maybe I am missing something, or can some applications not create/adjust UV etc on imported models?
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 From:  Ed
1690.9 In reply to 1690.8 
I use Hypershot for my renders. It is still a relatively new product and requires that UV coordinates come in with the import.

Ed
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 From:  manz
1690.10 In reply to 1690.9 
Hi Ed,

For a renderer to explicitly require external data on such as UV, would show a need to use another renderer.
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 From:  jbshorty
1690.11 In reply to 1690.8 
Hi Steve. It is a legitimate problem. Modo has tools for setting up UV's. But for certain types of surfaces, even simple ones like a revolved disc there is no easy way to get uniform UVs to match the desired concentric anisotropy. Well, there is a method using morph targets, reshape the surface into a cylinder, apply UV's, relax the morph, etc.... But the best and fastest way is just use the inherent UVs from the original Nurbs model. Now imagine the surface can be much more complex than the example i posted (which in fact, they usually are) and you'll understand why i don't want to spend time (possibly a LOT of it) to make UV's by hand which are inferior to the originals anyway. I need to spend as little time as possible setting up a render if I am to expect to meet my deadlines. And i do expect to! :)

For the moment, I am using Rhino to export all components which we're producing in various metal fabrications (about 60-70% of my workload) until i have the free time to experiment...

jonah
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 From:  jbshorty
1690.12 In reply to 1690.10 
I can think of a few more reasons! :)
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 From:  Michael Gibson
1690.13 In reply to 1690.11 
Hi Jonah, I kind of need some more information than just your original screenshot to be able to diagnose the problem.

It could help a lot to have the .3dm file posted, and also some other information that I mentioned previously:

quote:

What happens when you export OBJ from MoI into Modo - do you get a proper result from that or does it look the same as the LWO export?

If you get the same messed up result, that would help point me towards looking at the geometry and UV coordinates, and otherwise at more LWO specific stuff.

Also, can you see what happens when you export LWO from Rhino as well?


Also one other thing that may have an effect is if you are exporting in N-gons from MoI but triangles from Rhino... Maybe the way this function works in Modo makes it want to have a center UV point in there instead of only points around the outside...

I can certainly understand if you don't have time to do this right now, but it is pretty difficult for me to make any progress on this without some extra information.

- Michael
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 From:  jbshorty
1690.14 In reply to 1690.13 
Hi Michael. Might be a little while, but i definitely will send files to you because i would like to see it resolved if possible. Or perhaps it really is a Modo issue... Also i will have to add "all quad/triangles from MoI" onto the test pile...

Do you also want the Modo test file?

thanks,
jonah
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 From:  Michael Gibson
1690.15 In reply to 1690.14 
Hi Jonah,

> Do you also want the Modo test file?

Sure, that certainly might come in handy for testing as well.

If you did have a big n-gon at the top there with the MoI export, then that is most likely to be the single biggest difference between the Rhino export and the MoI one. That would mean that Modo wants to have an actual poly vertex at that central spot to make it work correctly, it is otherwise trying to some kind of interpolation across a polygon which is not working right. Right now that is kind of my best current guess but not verified of course.

- Michael
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 From:  DannyT (DANTAS)
1690.16 In reply to 1690.9 
Hi Ed,
>>I use Hypershot for my renders. It is still a relatively new product and requires that UV coordinates come in with the import.

I use Hypershot also, but have had no problem so far. I always export the model as .obj from MoI, because no matter what Hypershot allows you to import it always converts it to .obj.

Cheers
~Danny~
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 From:  manz
1690.17 In reply to 1690.11 
Hi jonah,

>>It is a legitimate problem.

It sounds like Modo is a pain on this point.
Can a 3rd party mapper, such as UV-mapper help? http://www.uvmapper.com/ (there is a free version)
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 From:  jbshorty
1690.18 In reply to 1690.17 
Thanks for the suggestion. But I'd rather not have to do any mapping at all. In that case, I'd rather just export from Rhino. Let's see what can be resolved using software which I already use... Modo actually has some nice UV tools, but missing something to handle a "revolved" disc...

jonah
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