Fillets and object size

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 From:  nycL45
2797.1 
Fillets seem to dramatically increase an object's size. I have enclosed a simple example of a curved frame without a fillet and one with a small fillet on one 3/4"/19mm wide face, both edges (see pic).

I exported these frames separately as .obj as ngons and at a setting of 9 (if the default setting of the slide at midpoint = 5 and extreme right = 10) so the tessellation would not be perceivable. (Observation: it seems the setting has to be quite high for large curved objects.) The .obj files were then opened in C4D. The file sizes look like this:
Without fillet
.3dm 32 KB
.obj 48 KB
C4D 76 KB

With fillet
.3dm 112 KB
.obj 976 KB
C4D 480 KB

Is there any advice on filleting objects in Moi without causing huge files?

Leonard

Image Attachments:
Size: 95.9 KB, Downloaded: 3 times, Dimensions: 437x485px
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 From:  Michael Gibson
2797.2 In reply to 2797.1 
Hi Leonard, yes an increase in file size is a normal side effect that will happen when fillets are applied.

Fillets are small curved surfaces and to make detailed curved things requires a fair number of control points. If you use Edit/Separate on your model, you can pick the fillet as an individual surface and turn on control points for it and see that there are usually quite a few control points that define the fillet surface.


> Is there any advice on filleting objects in Moi without causing huge files?

Well, basically adding detail adds file size along with it.

If you want to reduce file size then you correspondingly need to reduce details as well.

One thing that can help quite a bit to reduce size with more complex models is to use a chamfer instead of a fillet, since the chamfer is flat in one direction rather than curved and it will not have as many points in it. And if it is in a small sized area often you can't really notice the difference in a rendering.


But is there some particular reason why you are so concerned with the file size?

The sizes that you show there for the "with fillet" version are still pretty small files in the overall scheme of things... Those are not really at a size to be particularly worried about.

Are you using a very old computer or something like that?

- Michael
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 From:  WillBellJr
2797.3 
Since the goal for my modeling is to soften 90 degree corners to catch highlights, I've started using chamfers instead of fillets.

I end up accomplishing the same effect without the added polygon weight added by fillets.

Granted sometimes you want a round edge and can't do without the fillet but for my spaceship models and buildings etc., I can get away using the chamfers - my models feel way lighter as a result. Usually they're easier to edit in the polygon editor as well!

-Will
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 From:  nycL45
2797.4 
Hi Michael,

It was sticker shock, rush to optimize and "What did I do wrong this time?".

The basic frame referred to here is not at issue and that applies to most of what I produced with Moi. It has to do with the fillet and learning the more optimal export settings for the .obj ngons. With the latter, I re-exported some components at a lower and visually acceptable setting to bring sizes down.

So, it was the fillet I was in the dark about. In C4D, there is control with the fillet (Bevel) size and subdivision and thought perhaps there was a subdivision setting that I had missed with Moi. (Maybe in the future?)

Chamfer is the way to go, not as good, but the way in a lot of cases.

Edit:
I did not answer your question, Michael: >But is there some particular reason why you are so concerned with the file size?>

The arched window assembly I did in Moi weighed in at 23 MBs and there are three of them plus other windows which could have totalled 100 MBs. They are now a bit smaller and I will do some more shrinking.

Thanks.

Leonard

Hardware:(
Ancient 2006 MacBook Pro, 2.16GHz, 2GB, Mac OS 10.4.11

EDITED: 21 Jul 2009 by NYCL45

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 From:  lyes (BLYESS)
2797.5 In reply to 2797.1 
hi NY use keyboard shortcut to shrink surface to trimed edge you have to separate the polysurface first.
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 From:  nycL45
2797.6 
Hi Will,

As I noted above, I will use small chamfers more often for the corner reflection. When it comes to a room interior, corners will definitely need the fillet.

With Moi's ease and speed and my saved splines, I will re-make the exterior pieces with a chamfer.

Cheers,

Leonard
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 From:  nycL45
2797.7 In reply to 2797.5 
> shrink surface to trimed edge you have to separate the polysurface first.

Lyes, this sounds interesting but I do not understand. What does "shrink surface" mean? And, why do we have to "separate the polysurface" and how is that done?

Leonard
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 From:  Michael Gibson
2797.8 In reply to 2797.4 
Hi Leonard, well actually your hardware is not too terribly ancient..

Did you actually run into problems with the higher density files, did things actually bog down and go too slowly to use?

I would think that you probably don't have to worry much about this unless you are getting into quite a bit larger in size than that. (EDIT: - yes if you were getting into the 100MB range then that would be good to optimize)


> In C4D, there is control with the fillet (Bevel) size and subdivision
> and thought perhaps there was a subdivision setting that I had
> missed with Moi. (Maybe in the future?)

That's probably when you are producing polygon model output in Cinema4D - you can typically adjust the number of polygons that are used when generating polygon output.

In MoI things work quite a bit differently than that - when you create a fillet in MoI you are not building polygon output then, you are actually building a "perfect" circular fillet shape that is refined to be accurate to within 0.001 units tolerance.

That's one of the major differences between NURBS modeling and polygon modeling.

With NURBS modeling you are building something that is more exactly defined to be an accurate curved shape in its definition.

Polygons don't enter into it until later on when you save to OBJ format. (well, they also do enter into the viewport display but not the definition of your model data though)

At that time that polygons are generated, you will then have a similar chance to adjust the polygon density - you can use that slider to reduce the number of polygons that are generated and there is another setting on the full settings (push the little arrow in the lower left corner) called "Avoid smaller than" which can be useful for reducing polygon density in small details. You can enter a distance value there, and anything smaller than that distance in size will get a much rougher mesh angle applied to it so small details will get fewer polygons with that setting. So for example if you have fillets that are smaller than 0.5 units in size, you can enter 0.5 for that "Avoid smaller than" value and then those fillets will get a rougher meshing on them than the larger sized parts of your model.

- Michael
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 From:  Michael Gibson
2797.9 In reply to 2797.5 
Hi lyes,

> to shrink surface to trimed edge you have to separate the polysurface first.

A quick note - actually you don't have to separate your object to run ShrinkTrimmedSrf on it, that works on solids/joined surfaces as well.

But you do need to separate it if you want to see how the control points look like.

- Michael
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 From:  Michael Gibson
2797.10 In reply to 2797.7 
Hi Leonard, I'll just jump in also,

> What does "shrink surface" mean?

After you trim or do booleans, you can have an "underlying surface" that is larger than the trim curves on the surface.

There is some description and illustration of how trim curves and underlying surfaces work here:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

It is possible to set up a keyboard shortcut for a command named "ShrinkTrimmedSrf" which when applied will shrink the underlying surfaces of an object so that they are only as large as the trim curves instead of possibly having excess area.

That can actually reduce the 3DM model size if you have a lot of pieces that are booleaned out of larger initial surfaces. But usually it won't do that much for things that are heavy with fillets though, and it won't have any effect on the polygon generation to OBJ format for example.


> And, why do we have to "separate the polysurface" and how is that done?

That means selecting a solid and running Edit/Separate on it to break it into individual surfaces that are not joined to each other anymore.

You typically have to do that if you want to turn on control points for objects that have been booleaned, some more info on that in the above link.

- Michael
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 From:  lyes (BLYESS)
2797.11 In reply to 2797.9 
Hi Michael i did not know that nice tip
NY put short cut key
ALT+S ShrinkTrimmedSrf
and hit it whene you feel like it
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