topic Re: Simplifying Polylines/Curve Fitting in Visual LISP, AutoLISP and General Customization Forum

Simplifying Polylines/Curve Fitting

johnfischerLSI — Thu, 09 May 2024 19:26:55 GMT

I'm looking to drastically reduce the number of segments/vertices automatically. I'm hoping there's a method to fit a curve to a series of segments, and maybe set an angle tolerance. The goal is to make these files more machine-path friendly. Example DWG attached. Any help would be great appreciated!

Re: Simplifying Polylines/Curve Fitting

pendean — Thu, 09 May 2024 19:37:56 GMT

Like this perhaps https://www.autodesk.com/support/technical/article/caas/sfdcarticles/sfdcarticles/How-to-simplify-polylines-with-many-vertices.html#:~:text=Community-,How%20to%20simplify%20polylines%20with%20a%20large%20number%20of%20vertices%20in%20AutoCAD,-Autodesk%20Support

Re: Simplifying Polylines/Curve Fitting

Kent1Cooper — Thu, 09 May 2024 20:01:47 GMT

The article linked in @pendean 's Reply has a broken link to something in the Forums, which could possibly be my PLDIET.lsp routine [PLD command] -- if so, that is available >here<. But one aspect of the OP's request that it will not do is to apply curvature across multiple segments. It will keep existing arc segments if you choose that option, but only as they are. It only removes vertices, leaving line segments between the adjacent vertices that it left in place.

[WEED mentioned in that article is the name of a routine that was, originally at least, only for "heavy" Polylines. PLDIET was written to do pretty much the same with LWPolylines, with a few other improvements -- see the comments at the top of the file.]

Re: Simplifying Polylines/Curve Fitting

johnfischerLSI — Thu, 09 May 2024 20:02:42 GMT

I've tried using the PLDiet command, but it seems to just turn a series of segments into one long, straight segment. I'm hoping to achieve more of a "curve fitting" effect, if possible. If this is something PLDiet can do, please advise! I've attached a screenshot of an example I manually re-worked, I'm hoping to automate this process.

Re: Simplifying Polylines/Curve Fitting

marko_ribar — Fri, 10 May 2024 16:53:55 GMT

Here you have "dietlws.lsp" that may be what you are searching for...

https://www.theswamp.org/index.php?topic=59534.msg620732#msg620732

HTH.

M.R.

Re: Simplifying Polylines/Curve Fitting

johnfischerLSI — Thu, 09 May 2024 20:26:06 GMT

This is great! Is there any version of this that can allow you to select multiple polylines at once?

Re: Simplifying Polylines/Curve Fitting

marko_ribar — Sun, 12 May 2024 07:39:11 GMT

It did outer pretty well, but inner ones are trickier...

Here is your DWG...

Re: Simplifying Polylines/Curve Fitting

johnfischerLSI — Thu, 09 May 2024 20:39:53 GMT

This is almost exactly what I need, do you think there's a way to automate it a bit more to allow for simultaneous pline selection?

Re: Simplifying Polylines/Curve Fitting

Kent1Cooper — Thu, 09 May 2024 20:45:56 GMT

@johnfischerLSI wrote:

.... If this is something PLDiet can do, ....

No, it's not. It only reduces quantity of vertices, but cannot change line segments to arc segments.

Re: Simplifying Polylines/Curve Fitting

Sea-Haven — Fri, 10 May 2024 02:11:55 GMT

There is curve best fit algorithms. CIV3D has one built in. But knowing if curve produced is within tolerance to points would be the problem. Least squares comes to mind. Looking for a lisp version.

Found this Curve Fitting Algorithm - Lisp — BricsCAD Forum (bricsys.com) go down to Sakko post a couple of possible solutions. The circle one did give something to start with. Can maybe break at start and end.

Re: Simplifying Polylines/Curve Fitting

david.waight — Fri, 10 May 2024 07:00:17 GMT

@johnfischerLSI,

Could this be what you are looking for?

It isn't free and I haven't used it but it seems to be what you are looking for.

https://tcicorp.com/curvefit/

Re: Simplifying Polylines/Curve Fitting

marko_ribar — Fri, 10 May 2024 16:56:22 GMT

@johnfischerLSI

I've updated my *.lsp in the link I provided and now it should work with multiple selection of LWPOLYLINE entities...

HTH.

M.R.

Re: Simplifying Polylines/Curve Fitting

davidjnolan98 — Thu, 23 Jan 2025 04:05:40 GMT

In AutoCAD, the PEDIT command allows you to streamline polylines by straightening segments between chosen start and end points. Additionally, tools and add-ons like Simplify Polyline can automate the vertex reduction process. Also you can use curve fitting tool, upload your data, perform curve fitting, and export a simplified version to import back into AutoCAD for further use.