lwo normal issues  1-20  21

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 From:  rhumba
798.1 
Hi, I have noticed some strange results when using moi with Modo, exporting meshes as .lwo files.
It's great that moi exports vertex normals so things look nice and smooth, but I think there must be something weird going on since the lighting doesn't react correctly for the imported object, and shadows are all messed up.
Taking a simple render of a native sphere (left) against the imported sphere (right) from moi (the native sphere is subdivided so it looks smooth) you can see when shadows are turned on there is some nastiness:



If shadows are turned off, the lighting seems to be wrong in that the elevation is reversed:



I've tried it on quite a few models and its the same.

On a side note, I seem to have problems with using .obj since at the edges of fancy trims where there are some skinnier tris there is always some normal problem where they get smoothed with the wrong edges and it looks almost rippled instead of sharp. lwo seems to not suffer from this, but has the problems highlighted here.
Anoyone else have this?
This isn't a case of each vertex having just a single normal in the .obj is it? They have separate uv's across nurbs patch boundaries...
Anyway just trying to gear up for a nice render, any help appreciated.

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 From:  Michael Gibson
798.2 In reply to 798.1 
Hi Rhumba, so are you using the new Modo 301 for this test?

I didn't have a chance to actually test the vertex normals, so it looks like something needs to be flipped around. I'll post a test file with it corrected in a minute, if you could please test it out.

For the moment in the mapping options you should probably be able to see a "vert_normals1", "vert_normals2", etc... mapping channel defined somewhere that contains the vertex normals, if you delete those it should be restored to just regular polygon normals but that will be better than reversed normals.


> This isn't a case of each vertex having just a single normal in the .obj is it?

I don't know, I haven't been able to figure out why Modo mangles OBJ imports so badly, it just seems to have quite a few bugs in it. You can expand the mesh options dialog and uncheck "Weld vertices along edges", which will generate a somewhat more simple structured output with less shared stuff between faces.

- Michael
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 From:  Michael Gibson
798.3 In reply to 798.1 
Hi Rhumba, I think I had the normals reversed. Can you please give the attached LWO sphere a try and see if this one behaves properly? Thanks,

- Michael
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 From:  rhumba
798.4 
Hi,
sorry, this one has similar problems for me! I'm cannot be absolutely sure its a moi export issue since when exported back out as an .obj the normals can look ok again, but they have the rippling problems on edges. It seems this time the difference is more like azimuth (instead of elevation) (or x instead of z) but I can't be sure yet until I have more time.
Thanks for getting back so quickly!
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 From:  Michael Gibson
798.5 In reply to 798.4 
Hi Rhumba, here are 2 additional test files, each with a different configuration. When you get a chance, please let me know if either of these seems to work ok.

- Michael

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 From:  Schbeurd
798.6 
Hi Michael,

The three example file give me various (but "wrong") results in Modo. As I'm still using V.203, Is it useful for you that I provide screenshots or any other info ?
You probably know that Modo 301 has not been released yet. Unless you have some contacts with people using the beta of 301, we can only post results obtained with the current version... ;-)

BTW, I know that Siggraph is always a very busy moment but maybe you can take the opportunity to meet the Luxology folks during the event and discuss some of the issues with them. Both your and their customers would benefit from a perfect exchange of files between MoI and Modo !

EDITED: 25 Jul 2007 by SCHBEURD

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 From:  Michael Gibson
798.7 In reply to 798.6 
Hi Schbeurd,

> The three example file give me various (but "wrong") results in Modo. As I'm still
> using V.203, Is it useful for you that I provide screenshots or any other info ?

I don't think I need a screenshot, can you just describe what you're doing to see the differences?

I'm kind of confused as I thought only version 301 would read this data, I thought it would be skipped by earlier versions. But if you're seeing different results then I guess it must be reading it in now as well.

- Michael
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 From:  Schbeurd
798.8 In reply to 798.7 
Just loading the files into Modo gives me the following results (see attachment) :

For the three files, once I smooth the sphere (in Modo you can do that with a hit on the TAB key) it looks OK...

Really no idea of what's going on there...

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 From:  Michael Gibson
798.9 In reply to 798.8 
Ok, I think I found the bug in MoI's exporter.

Can you try this new sphere and see if it behaves now?

If this one works then after some more testing I will make another new beta tomorrow with this fix in it. This seems to mean that vertex normals work with the current version of Modo, not just 301. So that's good news once this is working properly.

- Michael
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 From:  Schbeurd
798.10 
Seems to work now ! ;-))

BTW, it seems that the discussions at Luxology about vertex normals were more related to OBJ than to LWO format.
See : http://forums.luxology.com/discussion/topic.aspx?id=17281
Based on the information there, do you think 301 will improve OBJ import as well ?



Great work Michael ! ;-)
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 From:  Michael Gibson
798.11 In reply to 798.10 
> Based on the information there, do you think 301 will improve OBJ import as well ?

Apparently so... I had originally took it to mean that Modo didn't support dealing with vertex normals at all until 301.

So that's great, it looks like I found the bug. Tomorrow I should be able to put out another new beta after checking over it carefully.

Thanks for your testing, and thanks to Rhumba for reporting this in this thread!

- Michael
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 From:  murky (MARCIN_WUU)
798.12 
Just on a side note.

None of these files caused any problems when rendering in LightWave

cheers

M.W.
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 From:  jbshorty
798.13 
the sphere test performed well in Modo over here also...
jonah
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 From:  rhumba
798.14 
Just confirming that lwo_normals_test4 works for me too!
The new beta hasn't got these changes in though, as far as I can tell. I get the same as Schbeurd's Normal Test 1 image still.
This must mean the final release is imminent!! :)
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 From:  Michael Gibson
798.15 In reply to 798.14 
> The new beta hasn't got these changes in though, as far as I
> can tell. I get the same as Schbeurd's Normal Test 1 image still.

Yeah, it doesn't have it yet, I'm planning on another new one today that will fix it up.

It should be nice when this is working right, having the correct normals will prevent little shading irregularities that can happen when trying to calculate the normals just from polygon faces alone.


> This must mean the final release is imminent!! :)

Yup, the software is pretty much wrapped up, just need to fix a few last bugs here... Then the only thing left is documentation which will take a little bit of time to complete.

- Michael
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 From:  Michael Gibson
798.16 In reply to 798.15 
Ok, finally got to the bottom of this lwo normals issue.

Regularly a LWO file has x,y,z coordinates specified in a left-handed coordinate system.

Just to make things interesting I guess, Modo decided to have vertex normal coordinates specified in a right-handed coordinate system instead.

Now that I've got that set up, things are working great with Modo 203 - accurate vertex normals are coming through and that makes for noticeably smoother shading. Shading artifacts are basically eliminated.

I need to check out a few other things, later today I should be able to make another new beta with this fix in it.


One additional note - if you want to edit the LWO mesh in Modo by yanking some points around, etc, you'll probably need to find some way to strip out the vertex normals. They're stored with labels like "vert_normals1", "vert_normals2", somewhere in the Modo UI these should show up. Modo does not seem to update these normals automatically when you move the geometry around, so the shading stays kind of locked in to its initial look despite how you drag points around. This is probably something that should be fixed in Modo to be handled more automatically.

- Michael
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 From:  Michael Gibson
798.17 In reply to 798.16 
I'm going to postpone the new beta with this LWO normal fix until tomorrow afternoon so I can add some additional diagnostic stuff to try and help track down these script errors.

So slight delay, but not long...

- Michael
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 From:  rhumba
798.18 
No problem, I understand that definitely needs priority.
I saw the same script errors when a colleague installed moi and tried to play with it though it never happened to me! He had antivirus software and was using IE7 by the way...
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 From:  Michael Gibson
798.19 In reply to 798.17 
A quick note - Modo 203 doesn't seem to properly handle any type of editing operation on a mesh with vertex normals, even flipping.

It will just flip the face orientations but the vertex normals will remain unaltered, this will cause shading problems with the face and vertex normals pointing in opposite directions.

If you export a closed solid from MoI, MoI will do some work to automatically orient normals towards the "outside" direction of the solid. But if you export open surfaces, there won't be any automatic orientation. Due to the Modo flipping bug, you won't be able to flip it properly in Modo so to render it properly you will need to turn on double-sided rendering for the render material.

I think I will tune this up so that open meshes will get a double-sided material set on them by default on export from MoI.

I still haven't seen if there is a way in Modo 203 to throw out vertex normals and return to auto-generated ones... If that was possible that would also fix the problem but at the cost of returning to less smooth shading.

- Michael
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 From:  rhumba
798.20 In reply to 798.19 
Well I have to thank you for tuning that up, my .lwo exports look super smooth now!!
(don't worry I will upload some examples soon....)

Thats unfortunate about Modo's normal handling.. I haven't had any flipped meshes yet. I hope Lux are aware of these issues? They seem to take a healthy interest in bug reports at least, but maybe not up to your standards Michael!
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