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DanielCFilho

Subdivision Surface Sphericals

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Hello, all.

I've searched the Cafe and the internet in general about this, but coudn't find a perfect solution. I'd like to know any method you guys use in order to model spherical objects when apllying them to SDS. I know that a standard sphere is not good for subdivision because of the poles of triangles that produce pinching and artifacts after SDS. I'm currently using the hexahedron to model any kind of spherical objects for SDS, cos' it's all made of quads and that way doesn't produce artifacts. But the problem is that an hexahedron, after subdivided, doesn't end up as a perfect sphere. It results in very subtle bulges that deform the shape of an exact sphere. So, if you guys have any suggestions, tips, on how to get a perfect sphere using subdivision It would be greatly appreciated. Thanks.

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The only way to achieve perfectly even subdivision on a sphere is to use all triangles. It cannot be done with quads just because of the nature of the shape.

You are right to use hexa rather than standard sphere, but that is the closest you're gonna get if you want to maintain quads. But you can get that closer to a perfect sphere using the spherify deformer. 

 

CBR

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Thanks, Cerbera.

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On 8/24/2017 at 0:55 PM, Cerbera said:

The only way to achieve perfectly even subdivision on a sphere is to use all triangles.

Is this one of those instances where you have to accept the evil to get the desired results? The ends justify the means? 

 

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19 minutes ago, Monstrphil said:

Is this one of those instances where you have to accept the evil to get the desired results? The ends justify the means? 

 

In this case the ends would justify the means if you need your tris for softbody squishy deformation for example. If not, then no, because hexasphere (all quads) with spherify deformer  = perfect sphere, so there'd still be no need for any triangles ;) With all that said, SDS does a better result with all tris than it does with tris and quads, so that's in there to complicate things further :)

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DEATH TO TRIANGLES

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The problem with the spherify deformer is that it can be idealy used only for a generic sphere. That will be almost never the case when modelling real objects. The general case will be objects WITH spherical parts. For example, the generic light bulb will end sphericaly, but the whole shape is something else. I keep finding online examples of techniques to achieve a spherical part under SDS, but never a good tutorial. For example, I've noticed that one thing that people do is to substitute the triangulated pole in the end of a standard spherical with a kind of quadrangular filling. But when I see that and try to emulate by myself, I never get the right result. I'll attach an example I found of a light bulb for instance. (I found those images on turbosquid. I don't know the protocol, but if I can't post it here, just let me know) - The thing being: if anyone knows any tutorials or anything about sphericals under SDS, I would appreciate it.

Light bulb SDS 1.jpg

Light bulb SDS 2.jpg

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I too would be interested in knowing how your light bulb was modeled. I've been trying to duplicate the top-but have not found an easy way to get your results. There must be a simple solution.

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On 28/08/2017 at 9:38 PM, DanielCFilho said:

 

Light bulb SDS 1.jpg

Light bulb SDS 2.jpg

This is just a standard sphere but terminating in a quad patch rather than a pole. 

 

If you have the HB modelling bundle with its quad-caps option it's literally 3 or 4 clicks to do this, but can also be done without it easily enough using a small plane as your centerpiece, the points-to-circle script, some quick brush smoothing and then using soft selection in dome mode to gently pull out the curve. You can optionally apply a spherify deformer to the sphere before you model the lower half if you want the top absolutely spherical.

 

CBR

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Thanks for the recipe, Cerbera. I'll try that. As I don't have the point-to-circle script, I've been using the FFD deformer to transform that small plane you say into a circle. I think I can get close. But I keep forgetting about the soft selection, I almost never use it for anything. Anyway, I've been searching the web for more clues about this, and what I've understood is that whatever method people use, the end result seems to be always just an aproximation, never the perfect spherical. Maybe one lucky day I'll find the perfect method by chance. Until then, thanks for the tips.

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