Spline to Polyline
Sunday, November 06, 2005
I work as a structural designer for a sign making company so I receive lots of artwork made with other non-AutoCAD computer programs like Adobe Illustrator and CorelDraw. In those programs when you export to a dxf or dwg file they export the curves as splines, which, at times, is counterproductive.
For the kind of work that I’m doing splines aren’t the best kind of AutoCAD entities. After trying many different solutions to transform the splines in plines, I finally found one which I’d like to share. There some autolisp routines available for that task but after doing some research, I found a way to do it without using any routine or software.
By the way, a Spline is a curved line formed by two or more vertices, or "control points", and a mathematical formula describing the curve(s) between them. A Pline, or polyline, is a line created by a series of shorter straight line segments.
HOW TO CHANGE A SPLINE INTO A POLYLINE
Step 1: WBlock the Spline
Step 2: Open the Spline dwg and Save it as an R12 dwg
Step 3: Save the Spline as a DXF file
Step 4: Insert the DXF into your new file
Step 5: Explode the DXF
Step 6: Pedit the segments as a Pline.
Source: http://home.pacifier.com/~nemi/1tips.htm#HOW%20TO%20CHANGE%20A%20SPLINE%20INTO%20A%20POLYLINE%20(by%20Garry%20Fisher)
For the kind of work that I’m doing splines aren’t the best kind of AutoCAD entities. After trying many different solutions to transform the splines in plines, I finally found one which I’d like to share. There some autolisp routines available for that task but after doing some research, I found a way to do it without using any routine or software.
By the way, a Spline is a curved line formed by two or more vertices, or "control points", and a mathematical formula describing the curve(s) between them. A Pline, or polyline, is a line created by a series of shorter straight line segments.
HOW TO CHANGE A SPLINE INTO A POLYLINE
Step 1: WBlock the Spline
Step 2: Open the Spline dwg and Save it as an R12 dwg
Step 3: Save the Spline as a DXF file
Step 4: Insert the DXF into your new file
Step 5: Explode the DXF
Step 6: Pedit the segments as a Pline.
Source: http://home.pacifier.com/~nemi/1tips.htm#HOW%20TO%20CHANGE%20A%20SPLINE%20INTO%20A%20POLYLINE%20(by%20Garry%20Fisher)
15 Comments:
Why not just use the flatten command on the spline? It turns the spline into an lwpolyline.
commented by 
Anonymous, 11/08/2005 4:34 PM
Anonymous, 11/08/2005 4:34 PM
The process could be simplifiesd:
Step 1: Save the drawing as R12 DXF. Within the Save dialog click Tools -> Options -> DXF Options -> Select objects. Then simply select splines to be written to a DXF file.
This one step replaces first three steps.
But this is not a good solution. The conversion approximates an AutoCAD spline (NURBS)as a polyline with hundreds of short line segments. PEDIT can smooth the polyline, but the number of segments even increases! Very bad for CNC. I have an alternate solution. My utility SPLINEDXF processes any DXF-file and converts all splines (if any) into smooth polylines with arc segments. Conversion tolerance is selectable. The number of segments is significantly less than by R12 DXF conversion. If you are interested, write me to:
k o m a r o v @ m a i l.l v i v.u a
(but pls. delete all spaces from my email address first)
Step 1: Save the drawing as R12 DXF. Within the Save dialog click Tools -> Options -> DXF Options -> Select objects. Then simply select splines to be written to a DXF file.
This one step replaces first three steps.
But this is not a good solution. The conversion approximates an AutoCAD spline (NURBS)as a polyline with hundreds of short line segments. PEDIT can smooth the polyline, but the number of segments even increases! Very bad for CNC. I have an alternate solution. My utility SPLINEDXF processes any DXF-file and converts all splines (if any) into smooth polylines with arc segments. Conversion tolerance is selectable. The number of segments is significantly less than by R12 DXF conversion. If you are interested, write me to:
k o m a r o v @ m a i l.l v i v.u a
(but pls. delete all spaces from my email address first)
step1- save as r12
step2- open new r12 drawing
step3- you are done!
step2- open new r12 drawing
step3- you are done!
Another method is to WMFOUT, then WMFIN.
Use the UL corner of the viewport as the insertion point, and scale 2X.
Use the UL corner of the viewport as the insertion point, and scale 2X.
Demo version of the utility SPLINEDXF could be found at www.caddepot.com
go to Express / Modify / Flatten Objects
and then select the spline, then say "no" when it asks if you want to delete hidden objects, and it will convert the spline into a polyline for you.
and then select the spline, then say "no" when it asks if you want to delete hidden objects, and it will convert the spline into a polyline for you.
Try this external tool. It converts splines into line and tangential arcs:
www.techni-soft.de/html/splineexplode.htm
www.techni-soft.de/html/splineexplode.htm
Try this external tool. It converts splines into line and tangential arcs:
www.techni-soft.de/html/splineexplode.htm
www.techni-soft.de/html/splineexplode.htm
try the dotsoft (http://www.dotsoft.com/freestuff.htm) SPL2PL.VLX
! warning !
the program 'spline explode' does not create tangential curves. a quick test show they do not meet tangentially
the program 'spline explode' does not create tangential curves. a quick test show they do not meet tangentially
I try save as spline to R12 dxf, and reopen. it's convert as 3D polyline, since then I can not join with other lines using PEDIT command [reach me:parhyang@nospam.yahoo.com]
the best command is flatten.
I have splines with elevations assigned that I want to use in a surface. Flatten won't allow me to retain their elevation property. Thanks for the R12 tip.
I have tried all of these and the flatten command is by far the best if you have the express tools.
I think the express tools is only available on the full version. Is that correct?
Thanks for the tip. It has been driving me crazy when trying to operate a CNC. Saving as a R12dxf creates very jagged linework instead of arc's. no good for CNC work.
I think the express tools is only available on the full version. Is that correct?
Thanks for the tip. It has been driving me crazy when trying to operate a CNC. Saving as a R12dxf creates very jagged linework instead of arc's. no good for CNC work.
thanks for the express tool tip!!!
but i have one question, what's the difference of "no" and "yes" to delete hidden object?
many thanks
-v
but i have one question, what's the difference of "no" and "yes" to delete hidden object?
many thanks
-v
