Cancel
Showing results for 
Search instead for 
Did you mean: 

Continuing surfaces with adjacent poles

Experimenter
Experimenter

Clipboard-1.jpgClipboard-2.jpgHello, I am an fairly advanced user of NX but I have trouble recreating the surfaces as depicted. Could anyone please help me and enlighten me how to do this? Given that NX can't snip surfaces ending in one point (like the nose section). And also can't change degree of these surfaces, when they are created using through curve mesh. I am only able to recreate similar surfaces but the adjacent poles (highlighted in the image) are never the same as the ones in the adjacent surfaces (although the surfaces are G2). Is there any trick to lock the poles to the adjacent surface edge poles (same number and position) when creating a new adjacent surface (using studio surface or through curve mesh)?

 

(The Images above are parts I am trying to recreate. Not the surfaces I have created.)

 

Thank you.

16 REPLIES

Re: Continuing surfaces with adjacent poles

Experimenter
Experimenter

The green surface is the one I am trying to recreate. This is what it should look like.Clipboard-4.jpgI can only get a similar surface when I am using simple construction and not constraining any edge.Clipboard-5.jpgBut I need to constrain and when I do so, more rows are added.Clipboard-6.jpgObvously using normal construction does not work.Clipboard-7.jpg

Re: Continuing surfaces with adjacent poles

Phenom
Phenom
@LukeBr,

What can help is the curve networks - if those are heavy (many poles and knots) then the resulting surfaces are going to be heavy as well. So, refining curves prior to creating final surfaces is another step in the process.

Typically, regardless of software being used, to get that type of precise pole structuring, you will have to use refinement tools like X-From and Match Edge after creating the initial surfaces. Surfacing tools typically don't give you that sort of explicit control unless you place a precise mesh of curves throughout the span of the surface being created and that can also end up not being exactly what you desire without additional refinements.
-Tim

Re: Continuing surfaces with adjacent poles

Experimenter
Experimenter

Thank you for the tips. But I am not sure if editing the curve network would work here because my boundary curves are already very simple. Using x-form after building the surface with trough curve mesh does also not work for me because I can't move the adjacent poles without loosing continuity.

 

Clipboard-8.jpg

Re: Continuing surfaces with adjacent poles

Valued Contributor
Valued Contributor
@LukeBr,

Hi,

I would first ask if you need to finish all your cv's at the same point... this is an issue for many different reason and should be use only if you need a 0radii at the end. you could try to cut it just 1mm from the end point, then you would have a section to make a 4 side surface with you g1 continuity. Then you close the tip with a fill surface and voilà!
You have the same issue with the one circled in yellow... if all cv's go to the same point your bond to have further issue's. Try using guide's that will go through the same shape and trim your shape afterward.

Re: Continuing surfaces with adjacent poles

Genius
Genius

Hi @TimF   To my understaning, Rebuid option in NX surfacing tools is just equal to "explicit control". Is my understanding wrong? Thanks!

Re: Continuing surfaces with adjacent poles

Phenom
Phenom

@LukeBr,

X-Form should have the ability to hold the existing constraints while you refine the surface. If not, then Match Edge can be used to correct the continuity that is lost when editing the pole structure.

I can only guess because I'm just looking at images, but the pole/CV structure looks too perfect - so I'm guessing there has been heavy editing using manual techniques (pulling/tugging of poles, continuity adjustments) - either that or the original model might have come from a subdivision type of modeler. That type of modeling is fairly new to me and I don't have a ton of experience in regards to the quality of surface it can produce.

 

Edited to bring in some other users who I know have a wealth of surfacing experience and knowledge and might be willing to weigh in on this topic.  @Cesare @Sandman @StevenVickers

-Tim

Re: Continuing surfaces with adjacent poles

Phenom
Phenom
@surfactant,

It depends on which of the options you choose. If you choose Degree and Tolerance, then you're going to loose control of the segmentation. If you choose Auto Fit, then many times you will end up with a very heavy surface (many poles and/or high degree). That is why the refinement with tools like X-Form, Refit Face, Match Edge and the like exist...sometimes there is no other way than to manually adjust "by hand" - the software can only do the math - it doesn't know what you want the shape to look like or what you find appealing to your eye.

According to the NX docs, the Rebuild options will not be available unless the Output Surface Option Construction is set to Normal - so if one uses Simple, then the Rebuild will not be available. For those sorts of things, the NX documentation can be an invaluable resource (Help on Context with the dialog open). I would also highly recommend reviewing topics under the Modeling Preferences so that one has a better understanding of what those choices can affect.
-Tim

Re: Continuing surfaces with adjacent poles

Genius
Genius

Hi @TimF  Thank you for your comments! Very helpful! I finally come to know about using Rebuild options along with other refining tools together to do "explicit control". And I would try to study "Modeling Preferences" carefully. Thanks again!

Re: Continuing surfaces with adjacent poles

Phenom
Phenom

@surfactant,

You're quite welcome.

 

Please try to keep in mind that there isn't an explicit set of rules for this type of modeling, there are only best practices or guidelines and then your own personal experiences. It's anyone's best guess what will result in a high quality surface using single commands in a mechanical modeler 100% of the time. The software just takes what you input, does the math and spits out a mathematical surface - if you require better than what is output, then you'll have to force it through refinement techniques and that's where things can turn into a dark art and most users run into a wall.

-Tim