Curves workbench

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Chris_G
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Re: Curves workbench

Post by Chris_G »

chrisb wrote: Tue Sep 06, 2022 10:41 pm Not sure if this is a feature request: When Geominfo mode is enabled, and I'm using TechDraw, then there are lots of errors shown in report view.
Hello Chris,
Thanks for reporting.
I think it should be fixed now.
dkwvt
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Re: Curves workbench

Post by dkwvt »

Hi Chris,
I am using the curves workbench trying to figure out the gordon surface and encountering some odd results.
I'm in early stages so I'm pretty sure I'm making mistakes and need guidance.
I don't see a new post option so before I landmine another post thread, how do I start here?
I have the questions, about freecad info and two files already posted in another section of the forum and was directed here.
Thanks, dkw
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Chris_G
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Re: Curves workbench

Post by Chris_G »

Hello,
Post in this thread, or open a new one with [CurvesWB] in the title.
dkwvt
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Re: Curves workbench Help with gordon surfaces

Post by dkwvt »

Hey all,
Bear with me, I'm not sure where this question belongs so I'm starting here.
I'm developing a 3d curved surface in the curves workbench and as I explore I'm getting some odd results I'm not sure how to resolve.
This has taken me a great deal of time experimenting and I'm not sure where the files are clean and or glitched.
I have a good Gordon surface I've toolpathed and machined in file AT17 cca frame pm, (the right half).
The surface geometry is not (drawn) right in the above file and I have attempted to re-contour in the next file AT17 J curves platform.
The anamoly is visible in the gordon surface next to freehand Bspline 004 in the center with some interesting folding moving out into the surface.
I have thrashed this to death with some improvement but I cant get it clean, time for Professional Help...!
Thanks again for your patience and help.

Code: Select all

OS: Windows 10 Version 1909
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.2
Locale: English/United States (en_US)
Installed mods: 
  * Curves
Attachments
AT17 J curves platform.FCStd
(82.86 KiB) Downloaded 30 times
AT17 cca frame pm.FCStd
(148.57 KiB) Downloaded 32 times
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Chris_G
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Re: Curves workbench

Post by Chris_G »

Hi,
The Gordon algorithm has to reparametrize the curves and find a common knot vector for all the curves of each group (the rails and the profiles).
In you example file, it is pushed to its limits since the profiles contact the outer guitar contour curve pretty regularly, while these same profiles contact the inner curve (near center seam) very close to its ends.
I am afraid the tool won't be able to perform fine until you change your profiles so that they contact the inner seam curve more regularly.
dkwvt
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Re: Curves workbench

Post by dkwvt »

Hi Chris,
I was actually wondering if that was the underlying cause, the algorithm seems to be "pleating"...
Good to know, I believe I can redraw the profiles with a more regular spacing while maintaining the radial geometry of the cca curve origination points on the centerline of the guitar.
Thank You for looking at this,its actually encouraging information... dkw
dkwvt
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Re: Curves workbench

Post by dkwvt »

Chris_G wrote: Tue Sep 13, 2022 10:11 am

I am afraid the tool won't be able to perform fine until you change your profiles so that they contact the inner seam curve more regularly.
Hi Chris,
I did a quick freehand redraw with the three inner b splines spread out on the center profile. Much improved!
I believe a little more strategy with the length of the center contour and the spacing of the sections will solve the problem with no loss of the underlying cca curve geometry.
Many Thanks! dkw
Attachments
AT17 J curves platform.FCStd
(89.46 KiB) Downloaded 30 times
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Vincent B
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Re: Curves workbench

Post by Vincent B »

How to convert a sweep_2_rail into a point cloud or/and point compound?
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Vincent B
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Re: Curves workbench

Post by Vincent B »

How to use the Approximate surface feature from a point cloud or point compound?
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Chris_G
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Re: Curves workbench

Post by Chris_G »

Vincent B wrote: Sat Sep 24, 2022 9:29 am How to convert a sweep_2_rail into a point cloud or/and point compound?
The shape of sweep_2_rail is a compound of vertexes.
Vincent B wrote: Sat Sep 24, 2022 9:31 am How to use the Approximate surface feature from a point cloud or point compound?
Approximate Surface only works on 2D array of points.
So a random point cloud or point compound that is not sorted into rows and columns cannot be approximated with this tool.
Use the Reverse Engineering - Approx Surface instead.
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