How to do this??

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 From:  Bobo (SLOBODAN)
530.1 

Hi all,

I'm wondering if someone can help me with attached file.
I'm trying to create a bowl of a sink but with not much success. I'm also not sure what's the best way to do this in MOI. I managed to do this with Michael's tutorial for network surfaces. So, i created this with the profile swept along two rails and one scaling rail. It doesn't behave as expected.


Thanks,

Slobodan

EDITED: 6 Apr 2007 by SLOBODAN

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 From:  Michael Gibson
530.2 In reply to 530.1 
Hi Slobodan - the sweep doesn't work too well there because of the steep vertical area where the sweep rails came together to a point.

Imagine your base profile moving along in slices as it moves towards that end point - as it gets close to the ends there is a lot of variation in the slices since the area becomes so steep there.


Probably the easiest way to do the basin here would be to extrude your outline downward and then fillet the bottom face using a blend-shape fillet. That would be fairly close to your outline, especially along the back side of the sink. But I guess it doesn't quite match the front side because you want more of a gentle curve downward there instead of it going straight down...


One way to make some progress is to cut things up a bit and do some sweeps in the easier areas to start with, I've attached a version with that started. Sometimes if you can shrink the difficult area down to a smaller region it can be easier to deal with it.

I'll see if I can come up with some other ideas...

- Michael
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 From:  Michael Gibson
530.3 In reply to 530.2 
Hi Slobodan, here is another stage - this was again cutting up the rails so that they had a more regular shape, this time sweeping downward. Now the difficult area has been further reduced... I think one more round of this in the other direction will make more progress.

- Michael
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 From:  Michael Gibson
530.4 In reply to 530.3 
And another stage - again splitting things off into an evenly shaped portion. This time I split those rails by some lines in the top view.

Now the odd areas to fill are a lot smaller, now possibly sweeping to a point in those spots won't make such a mess.

But you know what, after looking at this shape I think my earlier comment about extrude + fillet was a better strategy overall.

But if you want to get a more gentle curve along the front part of the basin, what you would do is instead of doing just a straight extrude down, you could put in a few cross sections and do a loft or sweep down, that will let you control the shape and put a gentle curve in there instead of it just coming down straight. But don't try to model the bottom rounded part with the loft, have the loft come down to a flat planar bottom, then put a fillet on that bottom to give you the round. Let me know if you would like some samples of this other strategy.

I think you'll get a better result in this case if you don't try to explicitly model the rounded bottom area, but instead let a fillet (possibly with a blend shape instead of circular if you want) do that rounding for you. Does that make sense?

- Michael
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 From:  Michael Gibson
530.5 In reply to 530.4 
Here is that other method - for this I trimmed out the tightly curved section of your vertical curves and drew a tangent line there instead. Then I did a couple of 2 rail sweeps with the vertical curves as rails (with preserve tangent mode) to sort of bring down your top profile but have it conform to your curves.

But then this version ends in a plane - now the rounded parts come much more easily just by using fillet.

Does that do the trick? It seems to conform pretty well to your original sketch curves, probably the rounded area is slightly different. If you don't want a completely planar bottom floor to it, model a slightly curved floor as a separate surface and then boolean or trim it into place before doing the fillet.

- Michael
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 From:  Bobo (SLOBODAN)
530.6 
Michael,

I'm just amazed how you manage to do everything.
Since I just got up I'll have look at them all and learn a thing or two from the master.
I was surprised Frency wasn't on it right the way. :) :) Nice bunch of people in here... :)

Thank you again and I'll let you know my findings.

Slobodan
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 From:  Bobo (SLOBODAN)
530.7 
It looks like this is not very easy thing to do..

I'm still strugling with it.. :(
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 From:  Michael Gibson
530.8 In reply to 530.7 
Hi Slobodan, are you still stuck on making the bowl part, or on some other part?

Did you check out the sink_5 version attached above? Does that result look ok to you? I can give you some more detailed steps on how that was created if that would help.

It is difficult to put a good smooth surface using exactly the curves that you drew - to make it easier I changed the ends of your curves to come down straight at the bottom instead of having a tight curve at the bottom, then used a fillet (with blend style shape) to produce the rounded bottom.

If you are still getting stuck with this approach, please post another model file of where you're at.

- Michael
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 From:  Bobo (SLOBODAN)
530.9 

Hi Michael and everybody else..

I had time again to play with my basin and this is as far as I got to my original design.
Now, how do I blend these two surfaces??


Thanks,

Slobodan

PS. In the mean time I also educated my self about surfaces and nurbs thing... :) :)

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 From:  Michael Gibson
530.10 In reply to 530.9 
Hi Slobodan,

> Now, how do I blend these two surfaces??

I think the easiest way is to let filleting do it for you. If you bring the sides of your sink straight down to meet the bottom in a sharp edge, you can then select that edge and do a fillet to round it. Check out the sink_5 version I attached above for a demo on what that would look like.

You also might be able to create a sweep along that area for your blended area.

But there are some problems with your current model that will get in the way of finishing it right now - there are a few little zig-zag areas:





Those little zig-zag type folds in the the bottom edge of your basin wall are going to get in the way of making a nice surface built off of it...

- Michael
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 From:  Bobo (SLOBODAN)
530.11 
Thanks Michael,

I didn't even notice thoes zig-zags until you pointed them out.
I'll go back to your model 5 and see what I can do with that.
I realy want to make it as close as posible to those curves that I drew. Also, flat bottom takes away reality of it. I want to make it as real as posible.
I'm always open to suggestions. :) :)

Slobodan
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 From:  Michael Gibson
530.12 In reply to 530.11 
Hi Slobodan - here is a way to avoid the flat bottom, attached as sink_6.zip.

What I did here is I took the model from sink_5.3dm above, and deleted the flat bottom.

I drew a couple of curves off to the side there, to make a sort of shallow curved surface to use for the bottom instead of the flat bottom. In this case I used a sweep with one rail to make a slightly curved piece, then centered it on the side piece and used Construct / Boolean / Merge to cut them with each other (Edit/Trim would also work), and then deleted the extra pieces. Then I used Edit/Join to join the remaining pieces together, and finally a fillet with a blend cross-section shape puts in the rounded portion along the bottom.

I think this is likely your best bet for making a clean construction here - don't try to model too much all in one shot, do the side parts and then the bottom part separately and let fillet do the work of making a smooth blend in between them.

Let me know if you want more details on any of these steps.

- Michael
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