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Meowx

Getting a round cap without creases

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Alright, kinda fundamental modeling question here.

 

Typically, when modeling something round that needs to be capped off smoothly (and no hole/point from lathing), I'll do something like this:

Animation_MasterScreenSnapz018.jpg

 

Unfortunately, this always seems to create creases - particularly in the three-point patches - that no amount of bias tweaking gets rid of:

Animation_MasterScreenSnapz019.jpg

 

I've included the model in the screenshot; it's just a 2-second deal with no polish or anything.

round_cap.mdl

 

Is this just a fundamentally bad way to model stuff, or is there a way to get rid of these creases? Thanks!

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Three pointers and 5 pointers are happiest being as flat as possible.

 

use them on a smaller portion of the curve you are trying to model

 

hemi.JPG

 

hemi.mdl

 

 

However I think you can get better results with the regular hole-in-the-center approach and make the hole VERY small.

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Here's a traditional dome with a very small hole. For almost any purpose it's invisible and it's easier to make than with no hole.

 

HemiRegular.JPG

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Excellent, thank you. I hadn't realized 3 points were as sensitive as 5 points when it comes to curves, but I suppose it only makes sense!

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>Here's a traditional dome with a very small hole. For almost any purpose it's invisible and it's easier to make than with no hole.

 

 

(As because the lightbeams can go inside the model)

 

Also when you "overscale" that last ring, that it covers the hole, can that cause any renderingproblems?

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Can Holes create problems in any kind of renderingsetup? AO? Radiosity etc?

(As because the lightbeams can go inside the model)

 

Also when you "overscale" that last ring, that it covers the hole, can that cause any renderingproblems?

I'm also curious about its effects on renders. And yes, in my experience, over-scaling the last ring (or sometimes even just scaling it really really close) produces rendering glitches.

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Show me a glitch and the model.

 

It's like anything else, if you do it wrong or use it wrong it won't come out right.

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Pretty simple really, just make the final ring inverted (obviously this falls into the "doing it wrong" category):

Animation_MasterScreenSnapz020.jpg

 

or really really small:

Animation_MasterScreenSnapz021.jpg

 

Here's the model with the final ring really really small, but not quite inverted:

Model2.mdl

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You'll find you have a lot more success if you create your model with a decently sized hole in the top and then...

 

Zoom in and make the hole a little smaller. And then...

Zoom in again and make the hole a little smaller.

You can do this several more times but at a point it gets ridiculous to scale the hole any smaller.

 

Just scaling the hole to a really small size without out zooming in tends to create those pinching artifacts.

 

Here is an example of zooming in multiple times and making the top hole smaller with your model.

I also attached a revision of your model where I've extruded one more time while making the top of the cone smaller.

For some reason there was minor surface discoloration before that and I suspect the Bias/Magnatude of the splines might have been off.

OpenTop.jpg

Model2_fixed.mdl

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Rodney shows you how it's done. It's easy enough to make the hole small enough for any useful purpose.

 

or really really small:

Animation_MasterScreenSnapz021.jpg

 

Here's the model with the final ring really really small, but not quite inverted:

Model2.mdl

 

On this one the ring has been scaled so small that I can't even see a ring no matter how far I zoom in. That's too small. :rolleyes:

 

It's a matter of doing the technique properly to get a good result much as we need to do many things in life properly to get a good result.

 

 

The only circumstance I can think of where a tiny hole wouldn't do is the 3D printing that people are doing that ostensibly need a truly closed shape.

 

V16 will have an STL exporter so people may get to experiment with work-arounds for that.

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Hi everybody,

 

To me your first model is good if you use the material "Porcelain".

Plus you use less patches and CPs :

 

withporcelaine.jpg

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