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Choosing correct lathe amount/setting?


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Greetings.

I've had a question pop up in my head while going through tutorials, looking at others' work and so on. I notice some projects set lathe cross-sections to 4, others to 6, or to 8. I saw one using 12. And I wonder "how would I know how many to use in my projects?"

So, I decided to stop trying to figure it out myself, and just ask. What a concept!

Is there a certain method used to work this out? Is it "pick one and adjust as you go?". Are there specific factors to determine this? Is it something where it's "okay" to choose too many or too few and adjust later as needed?

Thanks!

 

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In general it depends on what you are trying to build from it. Is it only a round object without any attachments? Than 4 can be fine.
6 is pretty uncommon if you ask me (in general it should be divideable by 4 because that makes it easier to work with on the axis evenly).
For really round objects in close up situations go with 8 or higher.

If you plan to attach something to it (for instance you want to attach an arm to a torso or something) you will likly be more happy with 8 or 12.
It is all about the structure of the splines / patches / CPs.

For better understanding you can have a look at this tutorial which should give you an idea about the structure topic (especially interesting: Starting 15:30): https://www.patchwork3d.de/basics-of-patch-modelling-80-en

Best regards
*Fuchur*

 

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 Is it something where it's "okay" to choose too many or too few and adjust later as needed?

Absolutely. As with most things in A:M how you model depends on things like;

1) What's your personal tolerance to patch creases

2) How is the model to be used; a standalone "prop" or something whose shape is going to be animated - a billiard ball versus Mike Wazowski

3) Does the camera get close enough to the model to see any patch creases

Speaking as someone who mostly models inorganic hardware from the middle of the last century (i.e. things that are assembled using many, many rivets) I want a rivet head (essentially a demi-sphere) that uses as few patches as possible but still looks good at arms length.

 

demi_spheres_12_16_16_24_onscreen.jpg

Here's a screen render of four medium grey (33% reflective) demi-spheres using the same 3cp cross-section spline, lathed 3X, 4X, 8X and 12X. The surface creases in the 3X and 4X are especially obvious in the top views. In my opinion 8X is the acceptable minimum while 12X is a waste of patches.

demi_spheres_12_16_16_24_outside.jpg

Here are the same models rendered "outside". Once again the 3X and 4X would be fine if they were in the background of the scene. Not so much if a main character uses them to gaze at their reflection.

However there are more tools at your disposal; manually adjusting spline magnitudes and the groups "normal weight" which is a material property you can apply to control how patch normals are averaged.

demi_spheres_12_16_4_24_onscreen.jpg

Here's four demi-spheres again but the third model now has only four, 3pt patches. All its' magnitudes have been tweaked for circularity and a material has been applied to it whose only attribute is a normal weight of 67%.

demi_spheres_12_16_4_24_outside.jpg

Here are the same models "outside". If you import this image and the previous, similar one into an image viewer and switch back and forth between them, it's clear the 16 patch model is more accurate. But for use as a rivet head, being able to replace a 16 patch model with a more than adequate 4 patch model really reduces patch counts.

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Very helpful answers!

So it's more a matter of use/function. That makes sense, now that I know how to think about it. 

That's a great link/video, Fuchur! I have never seen that one. 
It's crazy how many great resources are scattered around the web that I've never seen, despite all my searching.
Many times, the links I click on lead to broken pages or missing files, etc. Nice to see some gems out there.

Edit: Just realized that's your site, Fuchur. Excellent resource! I've got it bookmarked.

Thanks again :)

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I don't have much to add...

Mostly it depends on what you will do next with the shape.

Is your lathed shape merely the precursor form of something else (for example, Modeling an n-gon)? Then you want the number of splines that make it easy to define that next shape.

Is that shape going to have some repeating feature, like teeth on a gear? Then you need enough splines to make one tooth x the number of teeth.

Is your lathed shape something that needs to be attached to another mesh, like an arm is attached to a torso? Then you want the number of splines to be about the same as the splines you can attach to on the other object.

Is the lathed shape the finished shape? Then 8 is a safe choice. Not too dense but enough splines to make a smooth round shape.

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On 5/22/2021 at 2:18 PM, WolfsongCG said:

Edit: Just realized that's your site, Fuchur. Excellent resource! I've got it bookmarked.

Thanks again :)

Thank you very much :).

Best regards
*Fuchur*

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