Nice and smooth surface

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 From:  jki (JKISS56)
5295.1 
Hello all,
I am quite new here, and I would like to create the model of a railroad coach. The critical part is a corner of roof: there are 3 different curves and I don’t know how to cheat MOI to create a nice smooth surfaces...


I tried a various approaches, but always I get sharp edges on surfaces, or curious shape ...









And unfortunately the critical surfaces have a “millions” of control points, so i am not able to adjust it simply...



Is it possible to reduce somehow the amount of control points on surface?

Any advice is appreciated :-)

I tried to discover what’s the problem and found a couple of surprising “rules” or behavior, i don’t understand. But it’s better to start a new theme.

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 From:  DannyT (DANTAS)
5295.2 In reply to 5295.1 
Hi jki,

It'll be great if you could post the 3dm file with those curves so the guy's here on the forum could give you a solution using the same curves that you have, it's a bit difficult to troubleshoot your situation just with images.

Cheers
~Danny~
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 From:  jki (JKISS56)
5295.3 In reply to 5295.2 
Hi Danny,
the coach is quite big file, but same situation I have with this nice old bus :-)

rgds
Jozef
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 From:  TpwUK
5295.4 In reply to 5295.3 
If i have done this as you want it, then it was a case of seperating some of your construction lines and then joining things as needed to achieve the shapes with network and sweep. All surfaces but the little arc at the front are networked surfaces. Play with the parts and the network command and you will soon see how it was done.

Martin


EDITED: 26 Jun 2015 by TPWUK

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 From:  jki (JKISS56)
5295.5 In reply to 5295.4 
Hi Martin,
thank you...
looking to your solution I see the same "edges" :-(



Looking closer to the transition from flat part to curved, you can see the sharp transition


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 From:  Michael Gibson
5295.6 In reply to 5295.1 
Hi jki - it looks like you are trying to manually build the connection surfaces. Don't do it that way - you need to use filleting to generate those connection pieces for you and filleting will do the work to make its blending pieces be smooth to the other surfaces.

It's quite difficult to get the same result as filleting in a manual construction type method.

Basically you want to focus your initial work on building just the larger sheets of your object, and not focus initially on any of the more highly curved areas. Where you have a highly curved area, that is a transition in between 2 larger forms and you want the larger forms to be modeled separately and the transition comes from a fillet.

See here for some examples:

http://moi3d.com/forum/index.php?webtag=MOI&msg=2164.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=2164.4

http://moi3d.com/forum/index.php?webtag=MOI&msg=1002.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=3137.1

- Michael
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 From:  Michael Gibson
5295.7 In reply to 5295.4 
Hi jki, right now you're basically trying too hard to control every aspect of the shape directly.

You need to let either Fillets or Blend do some of the work for you, and doing that means that you won't directly model every single piece with your own curves. Instead try to have the pieces that you build directly be only for larger surfaces that have more of a single kind of shaping within them. When there is a portion of the object that is more tightly curved, that's a sign of an area that is in transition in between some of the broader shapes - don't model those transition areas directly, those are the ones that you want to have generated by filleting or sometimes by doing Blend.

In your case the transition area is in this region here:




Your main broad surfaces are like this:






Right now you've got so focused on building the transition areas directly that you're interrupting the broad forms and those are getting build in multiple separate stages - instead you want those broad forms to be one single larger surface that initially extends out a ways. As you've been seeing already, it's easier to build a smooth surface when it's done all in one single go.

Then those broad extended pieces can be intersected with each other and then filleted, or there is also a surface/surface fillet mechanism that can fillet between them directly.

A fillet or a blend is the main mechanism to generate something that's smooth to the surrounding areas.

You will also tend to get higher quality surfaces when each surface is not trying to do quite so many changes in shape within one single surfacing pass. When there's a change in shape especially when it's an area that is tightly curved, that is usually a sign that a fillet would be good to put in that area. Sometimes it's difficult to initially see where these should go since there is a natural tendency to draw every aspect of the shape. But you are seeing here the difficulties with trying to do the same work as fillets or blends directly.

- Michael

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 From:  Marc (TELLIER)
5295.8 
Hi,

Here's a try, curves have been merged and simplified with blends and rebuild.
A temporary surface is extruded to blend both edges after.

Marc



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 From:  shayno
5295.9 
I think you had all the components you needed to do what you wanted
some trimming and joining to get 2 continuous profiles and then a 2 rail sweep gives a good result

cheers
shayne



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 From:  jki (JKISS56)
5295.10 
Hello all,
many thanks for your help. I've got a really important ideas and rules, I am going to learn and train how to cretae a train :-)
Will inform about results...
Jozef
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