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Constructing an Offset-Curve

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Ben
Ben on 2 Dec 2014
Commented: Ben on 28 Apr 2017
Probably this question has already been posted several times, however I was not able to find an answer.
I have a smooth curve given as a set of X and Y data points and I am trying to constrcut an offset curve. Bascially my strategie was to search for the perpendicular direction at each point of the given [X,Y] data set and then follow this direction according to the desired offset. This works well for convex curves. However for concave curves, there will be a setback at certain points.
This is actually a very common problem in CNC programming. Commercial CAD and CAM software packages mostly offer a solution to this problem. Unfortunately I was not able to find a solution in matlab. Maybe I am looking in the wrong place...
I would be glad if someone could share their knowledge.
Thanks in advance! Ben
  2 Comments
Andries Paula
Andries Paula on 23 Feb 2017
Hey. Did you managed to find out what approche is the best ?

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Accepted Answer

Unai San Miguel
Unai San Miguel on 28 Apr 2017
The subject is not trivial, a nice description can be found in the Patrikalakis et al. ebook, Offset curves and surfaces. They also speak about the particular problems of CNC.
  1 Comment
Ben
Ben on 28 Apr 2017
I agree, it is not a trivial task! Thank you for your input, this looks very informative.

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More Answers (1)

Matt J
Matt J on 2 Dec 2014
You haven't said what properties your "offset curve" must satisfy, so this is just a shot in the dark. However, what you could do is create a binary image that is white in the region above or below the given curve. Then apply imerode(). Then, find the boundary of the eroded region using bwboundaries. Then, do a curve fit to the boundary points and call that your final offset curve.
  5 Comments
Matt J
Matt J on 2 Dec 2014
Guys, you're missing my point. Of course I know there must be more constraints. My point is that the discussion can't go forward without us being told what they are!!

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