Silk: a NURBS workbench
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- microelly2
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Re: Silk: a NURBS workbench
I'm not realy a friend of the surface object. It creates good approximations for the input data but the outcome is not stylish:
the poles grid in this case does not have a relation to the border faces and the face is a patch of the bspline surface. the waviness of the surface can be smoothed in a second step but it is the result of a brutal interpolation.
I think the task is to find a method which creates for a triangle gab definde by 3 nurbs surfaces a filler consisting of 3 unpatched nurbs.
in my example I used 3 ruled surfaces (along bezier curves) as borders (brown/pink ) and created inside the hole 3 nurbs red, blue green because there is only a small number of poles and because of the simple bezier curves the continuity is not anywhere 2 but the isocurve structure is naturally. The grid of the inner faces is scaled by factor 2 to show the balanced correlation between the knots of all faces.
for statistics:
the border curves have each 7 poles (two connected bezier curves)
the inner area has 36 poles - each segment is a 4 x 4 bspline surface of degree 3, so all edges are simple bezier curves.
here is my example file
https://www.dropbox.com/s/i6n5sas1ky5c6 ... fcstd?dl=0
the poles grid in this case does not have a relation to the border faces and the face is a patch of the bspline surface. the waviness of the surface can be smoothed in a second step but it is the result of a brutal interpolation.
I think the task is to find a method which creates for a triangle gab definde by 3 nurbs surfaces a filler consisting of 3 unpatched nurbs.
in my example I used 3 ruled surfaces (along bezier curves) as borders (brown/pink ) and created inside the hole 3 nurbs red, blue green because there is only a small number of poles and because of the simple bezier curves the continuity is not anywhere 2 but the isocurve structure is naturally. The grid of the inner faces is scaled by factor 2 to show the balanced correlation between the knots of all faces.
for statistics:
the border curves have each 7 poles (two connected bezier curves)
the inner area has 36 poles - each segment is a 4 x 4 bspline surface of degree 3, so all edges are simple bezier curves.
here is my example file
https://www.dropbox.com/s/i6n5sas1ky5c6 ... fcstd?dl=0
Re: Silk: a NURBS workbench
that's the same strategy i talked about a year ago:microelly2 wrote: ↑Wed May 23, 2018 8:13 pm I think the task is to find a method which creates for a triangle gab definde by 3 nurbs surfaces a filler consisting of 3 unpatched nurbs.
in my example I used 3 ruled surfaces (along bezier curves) as borders (brown/pink ) and created inside the hole 3 nurbs red, blue green
https://forum.freecadweb.org/viewtopic. ... 20#p187547
and that is precisely what i am comparing the filling surface to in my posts above july 29 2017
Silk has a system that handles N sided patches and gets G2 at the OUTER edges of each 'NStar' (but the center has a slight pinch, and it seems to get worse the more branches the star has) september 17 2017
they are lightweight and fast, but in my estimation, G1 filling from the surface workbench will often be better overall.
i used N 36 control point patches in N 6X6 cubic NURBS surfaces, and that is as far as i want to push it personally. The inner point placement can be refined, but i spent too much energy already in that. the long term goal for me was always to get the final surface using the OCC filling method. Trimmed fitted surfaces are generally considered the state of the art for odd hole filling, and if we keep scratching, we will uncover how to make the built in G2 functionality work.
july 29 2017
how did you generate your '3 ruled surface example'? can you run it on my 3 border surfaces in the model so we can compare side by side all 3 versions?
Re: Silk: a NURBS workbench
I hope it will happen soon!
- microelly2
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Re: Silk: a NURBS workbench
Yes I see it, nice to have already an implementation.emills2 wrote: ↑Thu May 24, 2018 5:41 am
that's the same strategy i talked about a year ago:
https://forum.freecadweb.org/viewtopic. ... 20#p187547
and that is precisely what i am comparing the filling surface to in my posts above
Silk_model_74_15.png
july 29 2017
Silk_model_74_11.png
july 29 2017
I aks me now how to make it easy to use.
Here is my scripthow did you generate your '3 ruled surface example'? can you run it on my 3 border surfaces in the model so we can compare side by side all 3 versions?
Re: Silk: a NURBS workbench
thanks for the script. it's a lot to digest, so could you load the final surfaces for your 3 piece corner? i'd like to look at them in a bit more detail before trying to understand how your script works.
- microelly2
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Re: Silk: a NURBS workbench
Silk WB still needs a logo for the add-on Manager
https://github.com/edwardvmills/Silk/issues/10
https://github.com/edwardvmills/Silk/issues/10
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Re: Silk: a NURBS workbench
PR created for new logo on master
https://github.com/FreeCAD/FreeCAD/pull/3128
Also Silk Workbench has been created but needs love
https://github.com/FreeCAD/FreeCAD/pull/3128
Also Silk Workbench has been created but needs love
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Re: Silk: a NURBS workbench
PM me an email address
There has been talk about moving to a git-based documentation system. But for now we've migrated the Wiki to a more recent version and I've been working on cleaning it up so that maybe when the day arrives and we do migrate to a different documentation framework that it'll be easier to do so.
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