Beginner question on exporting objects

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 From:  blarg
2603.1 
Hi,

I am very fond of MOI, but have a really noobish question - I hope it's not too dumb.

If I do model one of the things that would be a pain to do in sub-d in another package like for example a sphere with a star shape punched out or sth, what are really my options of rendering this in another 3d package? I am working with XSI, so the only thing I could do is export it as a mesh and hope it comes as clean as possible at a very high res, being quads with a couple triangles. If I would zoom into this it would have very jagged edges in the render or is there any other way to do it, except importing it to rhino as nurbs and rendering there? But then why would I buy MOI if I already have a NURBS modeler?

thanks,
Sven
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 From:  WillBellJr
2603.2 In reply to 2603.1 
One of the greatest things about MoI is its exporter!

If your rendering app handles the normals that are exported from MoI for your models, it should look >exactly< the same as it does in MoI!

I purchased Cinema 4D specifically because my MoI models after import looked exactly the same as they did in MoI - smooth and clean!


XSI for me came in 2nd with Lightwave being 3rd.

Again C4D is no-fuss where as with XSI you may have to tweak some things here and there. No fault of MoI, it just all depends on how your app handles the normals.

If it calculates its own normals (like Lightwave), it's not going to look as clean and smooth exactly like it does in MoI.

The mesh geometry MoI generates is exceptional so there's rarely any probs with the meshes!

-Will
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 From:  blarg
2603.3 In reply to 2603.2 
Hi Will,

I fear what I wrote was a bit unclear. I am not complaining about the quality of the mesh the exporter generates. Problem is, that it is output as a high resolution mesh, as I cannot import NURBS into XSI (or can I?- not too sure on that one).

So how do I get a nice but still workable mesh? I cannot convert the exported geometry to a sub-D mesh or am I wrong? It seems a bit difficult to work on a 3d obejct with a 300,000 tri count and for example texture it. But maybe I really do not understand the workflow you guys use - as I have no NURBS experience. Can anyone help me out with that one?


Sven
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 From:  Frenchy Pilou (PILOU)
2603.4 In reply to 2603.3 
< It seems a bit difficult to work on a 3d obejct with a 300,000 tri count
This is nothing!
Zbrush work with 20 000 000 polys object without any difficulties! (if you have hard memory inside computer)
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 From:  Michael Gibson
2603.5 In reply to 2603.3 
Hi Sven,

> Problem is, that it is output as a high resolution mesh, as I
> cannot import NURBS into XSI (or can I?- not too sure on
> that one).

You actually can by saving from MoI as .igs format, there is some kind of IGS format importer in XSI.

However, the whole area of NURBS in XSI is really pretty old and as far as I know has not been upgraded or really touched at all in many many years. So it tends to be rather buggy, you are probably better of with a polygon export.


> If I would zoom into this it would have very jagged edges in the
> render or is there any other way to do it, except importing it to
> rhino as nurbs and rendering there?

If you import it into Rhino as NURBS and render it in Rhino, Rhino also convert it into a polygon mesh in order to render it.

Basically the normal way that NURBS are rendered in most programs are by converting it to a polygon mesh.

So it is more or less the same thing if you export polygons from MoI.


> But then why would I buy MOI if I already have a NURBS modeler?

If Rhino does everything you need and you are completely happy with it, then you don't need MoI. But there are plenty of people that use them in combination for a couple of reasons - one is that MoI has a more modern and streamlined interface so it is easier to learn how to use, and also there are many Rhino users that use MoI for generating a higher quality polygon mesh from NURBS data.


> I cannot
> convert the exported geometry to a sub-D mesh or am I wrong?

That's correct - the exported mesh is generally not going to be appropriate for using for further sub-d smoothing, you use the exported polygons directly as they are, you don't apply further sub-d smoothing to them.


> It seems a bit difficult to work on a 3d obejct with a 300,000 tri
> count and for example texture it.

I think you're getting quite a bit prematurely worried about this...

I'm not really that familiar with XSI, but doesn't it allow you to select a kind of chunk of connected polygons fairly easily? If so then there really isn't a whole lot of difference if the chunk has 10,000 polygons in it or 1,000...

Also you're not going to be generating 300,000 polygon count results from every single model.

For example you were asking about an example with a sphere with a star cut out from it, like this:



Even generating a pretty dense mesh from that will produce something around 3,000 polygons:



This is already dense enough that you can zoom in and not see jagged edges:



Of course if you don't need to zoom in too closely it can be good to use a lighter mesh when possible to have generally smaller sized files. But if your models are not that complex there really isn't that much need to worry about it so much, you can just crank it up.

You only get to 300,000 polygons or beyond on more complex objects, and if your object has a lot of pieces to it, it is just really unusual to want to zoom in extremely closely to every single piece of a complex object...

I'm also working on some improvements to MoI version 2.0 to make it possible to assign materials to surfaces inside of MoI so that you won't have to do it later on to the polygon output, which will help to make things easier for more complex models.

- Michael

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 From:  jbshorty
2603.6 In reply to 2603.4 
"This is nothing! Zbrush work with 20 000 000 polys object without any difficulties!"

Yes, but at the most one might export a low-res mesh of just a few thousand polygons...
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 From:  blarg
2603.7 In reply to 2603.5 
Hi Michael,

thank you for your very detailed answer.


> If you import it into Rhino as NURBS and render it in Rhino, Rhino also convert it into a polygon mesh in order to render it.
> Basically the normal way that NURBS are rendered in most programs are by converting it to a polygon mesh.
> So it is more or less the same thing if you export polygons from MoI.

Correct me if I am wrong, but I thought this happened at render time, in the viewport the model would be much lighter and easier to handle.

Your example with the star cut from a sphere has a very sharp edge at the border. For the stuff I do I need very smooth curvature in those areas otherwise it would not look convincing in the render. I have that control with Sub-D, but there is some stuff that is nearly impossible to do - like the shapes cut from a sphere.


I have attached an example where I made a nice fillet in MOI. It looks clean and smooth inside MOI, but I see no way transferring it anywhere where i can use a decent renderer to generate a nice picture from that - excpet Rhino I guess. I do not own that program nor have I ever used it , it is plainly the only NURBS package that I know the name of (besides MOI, of course). I know there are a couple other packages out there



So back to the star-cut-from-sphere-problem - is there any solution for this?
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 From:  Michael Gibson
2603.8 In reply to 2603.7 
Hi Sven,

> Correct me if I am wrong, but I thought this happened at
> render time, in the viewport the model would be much lighter
> and easier to handle.

It will happen any time the surface is shown as a shaded display - it would only not happen in a viewport if the viewport was showing a wireframe display with no shading in it at all.

For example if in Rhino you switch the viewport display from wireframe to shaded, you will see a message that says:
"Creating rendering meshes... Press Esc to cancel"

There are a few other programs do create a special custom mesh at every render frame so that they can make a customized one that adapts itself to that exact view. But Rhino does not do that, since it tends to be a time consuming operation to create meshes over and over again.


> It looks clean and smooth inside MOI, but I see no way transferring
> it anywhere where i can use a decent renderer to generate a nice
> picture from that - <...>

Why would you think that?

You can get a great picture from any pretty much any renderer of that, just look in the MoI gallery for a whole bunch of examples of just that kind of stuff with a variety of renderers: http://moi3d.com/gallery/

Just make sure you are doing the import properly - you need to use a format that supports vertex normals like OBJ, and if there is an option for reading in vertex normals, make sure that option is enabled.

If you are using XSI, that's an option called "Import Normals as User Normals", make sure it is turned on.

There is a previous discussion and some example of importing MoI models specifically into XSI here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=656.15

As you can see in the screenshot in the second message down there, if you enable reading in vertex normals you can get a perfect shading of your object since the shading will come from normals that were calculated from the NURBS surface, rather than just being averaged from all the adjacent polygon normals.


> So back to the star-cut-from-sphere-problem - is there any solution for this?

Your example there looks similar to the kind of stuff that you will get if you do not read in the vertex normals from the file.

What was your setting for the "Import Normals as User Normals" in that case, enabled or disabled?

Also can you please post the .3DM model file of your star? That will let me show you a few quick examples of how your exact model looks in a few different renderers.

- Michael
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 From:  blarg
2603.9 In reply to 2603.8 
Hi Michael,

> It will happen any time the surface is shown as a shaded display - it would only not happen in a viewport if the viewport was showing a
> wireframe display with no shading in it at all.
> For example if in Rhino you switch the viewport display from wireframe to shaded, you will see a message that says:
> "Creating rendering meshes... Press Esc to cancel"

Ah- I see. I did not know that.

> Just make sure you are doing the import properly - you need to use a format that supports vertex normals like OBJ, and if there is an
> option for reading in vertex normals, make sure that option is enabled.
> If you are using XSI, that's an option called "Import Normals as User Normals", make sure it is turned on.

I did not know about this either. The rendering looks exactly like I wanted it now.

It seems this whole discussion became so lengthy because of my total lack of knowledge in the NURBS field, I should have done some searching on the forum. Please accept my sincere apologies. Looking back now my questions were pretty stupid.



thanks,

Sven
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 From:  Marc (TELLIER)
2603.10 
There's no stupid questions, there's a lot of details to grasp when you get involved in 3d, especially when using different programs.

Somebody else will surely learn from your question !

Marc
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 From:  BurrMan
2603.11 In reply to 2603.10 
I was going to punch in this thread where MG talks about G1, G2 etc... ANd points out that it can affect the specularity buildup on those edges. Seems the issue was solved with an import setting but this still may be relavent to smoothing those edges in your render.

http://moi3d.com/forum/index.php?webtag=MOI&msg=290.2
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 From:  Michael Gibson
2603.12 In reply to 2603.9 
Hi Sven, they were good questions.

You probably would have figured it out yourself if XSI used something less cryptic for that label, like if it said "Load shading normals from file".

Also there would only be kind of rare instances (if any at all) that you would want to disable that, so they should have it default to on instead of off...


But anyway now that you know that import option should be on, you should get proper results - your new screenshot there looks perfect!

- Michael
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 From:  WillBellJr
2603.13 
I'm glad you've solved your problem - I guess my reply wasn't too clear to you as well.

I had eluded to the fact that if the program doesn't display the normals properly as MoI provides them, you're going to see the artifacts that you experienced and provided screen caps to show.

Yes, with XSI you have to make sure you read in the normals that MoI provides upon import.

I still at times find that Cinema 4D's display of MoI objects is cleaner than XSI's. Admittedly, I haven't tried v7.5 all that much since I've been focusing on C4D and Lightwave lately so I don't know if anything has been improved in this area...

-Will
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