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How to maintain smooth when make detail on the curve surface?


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That surface does not contain enough polygons to hold that level of detail so SDS deformation is inevitable, but is made worse in this case by the illegal poly types you have allowed at the corners. Convex quads (any internal angle >180 degrees) are absolutely terrible for SDS, and there are 4 of those you need to get rid of before there is any chance of getting this deformation-free...

 

The mistake happened almost right out of the gate in the choice of how many radial segments the overall form needed. The 8 you have is nothing like enough if you want to support smaller details like USB ports etc etc. So short of starting again with much more radial segments (32 minimum), then we could try and fix what you have, but it'll be an incomplete victory until we start changing the fundamentals...

 

image.png.9f3ab128cc00fcc12f5a5bbef67b6dde.png

 

So, the solution to this is to run more edges from that section all the way around the model, or you can smooth subdivide the whole mesh at Level 1 before cutting that detail in, which will double the amount of polys everywhere, and probably provide enough to support that detail without such a massive 45 degree digression from the established edge flow, which is what is responsible for the unattractive corner bulging here....

 

CBR

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  • Solution

Now, here's a better way to solve that, without adding more edges that flow all around the model, and eradicating the error-state convex polys you had before...

 

image.thumb.png.08f7dba045b09931022180031a8a32f8.png

 

However this is not a real solution because a) it leaves complex poles on curved surfaces, another rule of SDS modelling we shouldn't ignore, and b) because the curvature of the underlying surface has never been adequately established, so it has been impossible to fix this area and still maintain the (presumably) rounded profile you need there. So now this has considerably less SDS bumping, because we solved the error-state polys, but now it doesn't follow the overall curves of the object, so is still wrong and evidently not the ideal solution !

 

Now we do have to ask ourselves if ALL the edges in the port perimeter are necessary to achieve that shape, and the answer is no. So we could lose at least 2 edge loops from there without affecting that shape too badly, which will minimize the amount of other loops you need to add, but it is still better practice to evenly subdivide the model everywhere, rather than specifically where you need detail, when the overall curvature is so broad, and the primary curves distributed so widely across the model.

 

So with that knowledge in mind, what we actually need to do is remove that port altogether, and go with my second suggestion above, which is to apply 1 (or 2 max) levels of staged subdivision when you have the base shape correct, which will nail that into physical topology and 'establish your curvature', which will then be strong enough to hold the port you will subsequently cut into it. Then you place that under a NEW SDS object that adds just 1 or 2 final levels of live subdivision to put your silky smooth hi-res curves back. The cumulative SDS level should never be higher than 4 (and more ideally 3!) unless you are using SDS edge weighting, which doesn't apply here.

 

The extra polygon density will have the secondary benefit of minimising the effect of contra-flow diagonals such as those you get with inner extrudes, probably to the point where any remaining deformation is so subtle that 99% of eyes will miss it altogether...

 

Hope that makes sense...

 

CBR

 

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5 hours ago, Cerbera said:

Now, here's a better way to solve that, without adding more edges that flow all around the model, and eradicating the error-state convex polys you had before...

 

image.thumb.png.08f7dba045b09931022180031a8a32f8.png

 

However this is not a real solution because a) it leaves complex poles on curved surfaces, another rule of SDS modelling we shouldn't ignore, and b) because the curvature of the underlying surface has never been adequately established, so it has been impossible to fix this area and still maintain the (presumably) rounded profile you need there. So now this has considerably less SDS bumping, because we solved the error-state polys, but now it doesn't follow the overall curves of the object, so is still wrong and evidently not the ideal solution !

 

Now we do have to ask ourselves if ALL the edges in the port perimeter are necessary to achieve that shape, and the answer is no. So we could lose at least 2 edge loops from there without affecting that shape too badly, which will minimize the amount of other loops you need to add, but it is still better practice to evenly subdivide the model everywhere, rather than specifically where you need detail, when the overall curvature is so broad, and the primary curves distributed so widely across the model.

 

So with that knowledge in mind, what we actually need to do is remove that port altogether, and go with my second suggestion above, which is to apply 1 (or 2 max) levels of staged subdivision when you have the base shape correct, which will nail that into physical topology and 'establish your curvature', which will then be strong enough to hold the port you will subsequently cut into it. Then you place that under a NEW SDS object that adds just 1 or 2 final levels of live subdivision to put your silky smooth hi-res curves back. The cumulative SDS level should never be higher than 4 (and more ideally 3!) unless you are using SDS edge weighting, which doesn't apply here.

 

The extra polygon density will have the secondary benefit of minimising the effect of contra-flow diagonals such as those you get with inner extrudes, probably to the point where any remaining deformation is so subtle that 99% of eyes will miss it altogether...

 

Hope that makes sense...

 

CBR

 

Thank you for your reply sir.According to your suggest,it seem look better.But still not so perfect,how can i do it better?

1.png

2.png

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I think you need to keep "flow" of polygons, relative evenly spaced etc...

 

Let´s take your example with hole. You first make a lot of details (hardening edges for SDS etc.) but not have enough geometry for other parts. I was convert your SDS into polygons to get this mesh...

1.thumb.png.8e8950ca97959e2efd2ef987c63df6db.png

 

...then select edges marked with red color and with slide tool in clone mode scaled down and adjusted corner points as needed also with slide tool. Slide tool is great because components move just over surface and not "brake" smoothness too much.

 

2.thumb.png.8bbf0df50da26d82d41228bdc467b6fe.png3.png.84fb5c82a485d8fefd021c8ec347137a.png

 

Sure surface is not evenly oval, it´s just rough example, you need to slide points to positions where you need, but it´s posted as posible workflow...

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3 hours ago, elvisxie said:

how can i do it better?

 

You just have to model with a lot more care and precision and attention to the rules of SDS modelling. For example your new version has triangles, which are not allowed under SDS on curved surfaces, and always lead to deformation and lumpiness. 

 

CBR

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1 hour ago, Cerbera said:

 

You just have to model with a lot more care and precision and attention to the rules of SDS modelling. For example your new version has triangles, which are not allowed under SDS on curved surfaces, and always lead to deformation and lumpiness. 

 

CBR

Yes sir ,but sometimes i don't know how to resolve the triangles.

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Just now, elvisxie said:

Yes sir ,but sometimes i don't know how to resolve the triangles.

 

Unfortunately that skill is beyond any single forum post to teach. Becoming good at modelling, and being able to solve problems like this takes years of experience. Hence we have tried to show you ways to make this without putting them there in the first place so you have nothing difficult to solve.

 

CBR

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4 minutes ago, Cerbera said:

 

Unfortunately that skill is beyond any single forum post to teach. Becoming good at modelling, and being able to solve problems like this takes years of experience. Hence we have tried to show you ways to make this without putting them there in the first place so you have nothing difficult to solve.

 

CBR

Thank you sir,i will do more modelling.

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3 hours ago, bezo said:

I think you need to keep "flow" of polygons, relative evenly spaced etc...

 

Let´s take your example with hole. You first make a lot of details (hardening edges for SDS etc.) but not have enough geometry for other parts. I was convert your SDS into polygons to get this mesh...

1.thumb.png.8e8950ca97959e2efd2ef987c63df6db.png

 

...then select edges marked with red color and with slide tool in clone mode scaled down and adjusted corner points as needed also with slide tool. Slide tool is great because components move just over surface and not "brake" smoothness too much.

 

2.thumb.png.8bbf0df50da26d82d41228bdc467b6fe.png3.png.84fb5c82a485d8fefd021c8ec347137a.png

 

Sure surface is not evenly oval, it´s just rough example, you need to slide points to positions where you need, but it´s posted as posible workflow...

Thank you sir,Your topology is so clean.

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34 minutes ago, Cerbera said:

 

Unfortunately that skill is beyond any single forum post to teach. Becoming good at modelling, and being able to solve problems like this takes years of experience. Hence we have tried to show you ways to make this without putting them there in the first place so you have nothing difficult to solve.

 

CBR

Excuse me sir,i have another question.That is i don't want the corner so smooth,i think i have to add 4 edges in the 4 corner,then the problem is coming,the surface is not smooth like before,how can i add edges in this case? Thank you again.

微信截图_20210324211624.png

smooth.c4d

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If you bevel this centre loop you will tighten the corners...

 

image.thumb.png.306762c475fed45cb8c1e946644e4f75.png

 

I used just 1 subdivision in that bevel to get this result... and it doesn't cause deformation because I have run those loops all the way around the model. I also evened out the poly distribution as well, which was uneven enough to be affecting things negatively how you had it before. Notice regular even polys = regular even shape !

 

image.thumb.png.f14da6b268111e57cf1e6487bf3be377.png

 

CBR 

 

 

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