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Spline from lines

Valued Contributor
Valued Contributor

Hi,

 

I scanned an object on or  CNC CMM machine, from the scan I get an .iges file.

The iges file contains the curve that I scanned but its divided in lines.

When I use the command 'smooth curve string' some of the lines are not selected and I get an error 'selected section curves include branches'.

Anyone an idea what I'm doing wrong?

image.png

 

I want to create a spline from the lines and then use the command "smooth spline" to get get a smooth curve that I can use.


Regards,
Sven

NX11.0.1
6 REPLIES

Re: Spline from lines

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Based on your error message, it sounds like you have overlapping curves. Eliminate the overlapping curves and try again.

 

If the above does not work, try the "join curve" command; it should create a spline from the input curves. You may need to "smooth spline" the result.

 

If that does not get something good enough, I would put the scanned curves on a visible but not selectable layer, then use the studio spline command to create a spline on top of the curves. Tweak the poles of the spline until it matches "good enough".

Re: Spline from lines

Valued Contributor
Valued Contributor

The join curves command gives an error "gaps in sring or multiple loops".

 

Another option is to set a point on each startpoint of each line and use fit curve command.

But thats not something that can be done manualy.

 

I found a similar thread and there they sugested a NXopen program but the program doesn't work for me, it just gives some errors when I run it.

https://community.plm.automation.siemens.com/t5/forums/v3_1/forumtopicpage/board-id/NXDesignForum/pa...


Regards,
Sven

NX11.0.1

Re: Spline from lines

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Getting back to the root cause, it sounds like you have overlapping (or nearly overlapping) curves and/or small gaps between curves that should be connected. When you imported the IGES file, did you use the "optimize" option? This is supposed to help eliminate overlapping curve entities. Also, in NX 10 there is the "optimize 2D curve" command which should eliminate overlapping curves. I'm not sure how well it will work if your curves do not all lie in a plane.

 

If those commands do not do the job and you do not want to manually hunt down and eliminate the offending entities, then I'd fall back on the "studio spline using the original curves as a guide" strategy mentioned in my previous post.

Re: Spline from lines

Valued Contributor
Valued Contributor

I used the optimize function but no difference.

With the "optimize 2d" function the overlapping curves were removed but it diden't leave a continious spline.

Below is a closup to illustrate what I mean.

image.png

 

I created a journal that creats a point on every start of a single line.

With the points I can use the "fit curve" command.

 

Thank you for the help and interest!


Regards,
Sven

NX11.0.1

Re: Spline from lines

Phenom
Phenom
What are your scan data output options? Can you output only the points from the scan? If it were me, I'd go that route. You can create a spline (fit curve) in NX from all those points, keep it as reference, then refine it so you can segment & smooth it out where needed.

The CMM software probably isn't going to process the curve the same way you can in CAD (degree, segmentation, etc.). All of this, of course, depends upon how much you can or are allowed to deviate from the original scan.

Of course, cowski's suggestions are also valid if you must use the resulting curves from the scan data but they sound like they're pretty useless IMO since they came in as small line segments.
-Tim

Re: Spline from lines

Valued Contributor
Valued Contributor

The output from the scan was also my first tought.

I'm not familiar with the CMM and the software, its a different department.

I asked the guy who scanned the part if he has other options to output his scan data but he diden't know.

The part is already removed from the machine and the machine is occupied for the moment so I cant repeat the program.

Next time were gonna look at it if there are orther options to output the data.


Regards,
Sven

NX11.0.1