Silk: a NURBS workbench
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Re: Silk: a NURBS workbench
in other news, i finally learned to use the surface filling tool thanks to Microelly2 and Chris_G.
this tools adds a huge value to the Silk workflow because it is overall better at patching the final holes near corners (not always the corner itself). i can only get it to do G1 at the edges, but it looks great in the center of the fill. My NStar grids and surfaces are G2 to the surrounding surfaces, but very ugly in the center., and the degenerate triangle was only ever meant as a placeholder.
downgrading the edge is definitely worth it overall.
degenerate triangle(the area of interest is the LIGHT blue triangle hiding in the big light blue area up top): .
surface > filling: 3 edges, G1 to each face same scenario for stars: here is 3Star filling a corner .
and the surface> filling
this tools adds a huge value to the Silk workflow because it is overall better at patching the final holes near corners (not always the corner itself). i can only get it to do G1 at the edges, but it looks great in the center of the fill. My NStar grids and surfaces are G2 to the surrounding surfaces, but very ugly in the center., and the degenerate triangle was only ever meant as a placeholder.
downgrading the edge is definitely worth it overall.
degenerate triangle(the area of interest is the LIGHT blue triangle hiding in the big light blue area up top): .
surface > filling: 3 edges, G1 to each face same scenario for stars: here is 3Star filling a corner .
and the surface> filling
Last edited by emills2 on Mon May 21, 2018 2:38 am, edited 2 times in total.
Re: Silk: a NURBS workbench
the filling has better rounding, and it ends up so close to G2 in practice (on a G1 setting) that the NStar has no practical advantage:
look at the red dot at the center / left / up. go three zebra lines to the right and look below: a slight G2 error. but the highlight runs clean and smooth acrosss the toughest spot, where the 3 surfaces meet. here, although there is perfect G2 at the seam (near red dot), the zebra gets mushed and ugly where all three surfaces connect. it certainly doesn't 'flow' so i'm going to give up on improving the NStar stuff, after all i was waiting for the surface tool in a way.
I still see some value in Silk because it allows me to generate all the inputs for final surface filling with lightweight surfaces, and can reach G3 on the edge blends. and 3D splines.
look at the red dot at the center / left / up. go three zebra lines to the right and look below: a slight G2 error. but the highlight runs clean and smooth acrosss the toughest spot, where the 3 surfaces meet. here, although there is perfect G2 at the seam (near red dot), the zebra gets mushed and ugly where all three surfaces connect. it certainly doesn't 'flow' so i'm going to give up on improving the NStar stuff, after all i was waiting for the surface tool in a way.
I still see some value in Silk because it allows me to generate all the inputs for final surface filling with lightweight surfaces, and can reach G3 on the edge blends. and 3D splines.
Re: Silk: a NURBS workbench
just wanted to flag you that i have a use case that is very important (to me) for the surface filling tool (in the few posts above). i also used it for someone else here in a 'pure FreeeCAD context': https://forum.freecadweb.org/viewtopic. ... 20#p234293ulrich1a wrote: ↑Sun May 13, 2018 6:28 pm ...The surface workbench provides in its current state no minimal surfaces. I played with this workbench some time now, in order to find something useful that can be done with it, in order to add it to the documentation. I still have no really convincing example except of the acoustic foam example from Wilfried. I may need to concentrate on Cars.
Ulrich
it doesn't always work perfect, but it accomplishes a very advanced task.
Edit: Also, it could be used to repair a step file with a broken surface. happens all the time, and it's often a difficult thing to fix. rebuilding solids with bad seams is an important function
Last edited by emills2 on Mon May 21, 2018 5:08 am, edited 1 time in total.
Re: Silk: a NURBS workbench
the surface filling tool doesn't give much console feedback as to parameter use
but the parameters can be found and manipulated through the python explorer .
including forcing the G2 parameter to return a surface, whether it wants to or not this is the part that is odd to me. i can guarantee the surface loop is a valid candidate for G2, since all the corners of the surface loop are G2 to each other.
.but the parameters can be found and manipulated through the python explorer .
including forcing the G2 parameter to return a surface, whether it wants to or not this is the part that is odd to me. i can guarantee the surface loop is a valid candidate for G2, since all the corners of the surface loop are G2 to each other.
Re: Silk: a NURBS workbench
Would be perfect for modeling a car after crash
- microelly2
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Re: Silk: a NURBS workbench
can you please upload the grey face, I want to look inside to understand why it is so wavy.emills2 wrote: ↑Mon May 21, 2018 2:57 am
including forcing the G2 parameter to return a surface, whether it wants to or not
Silk_model_143_07.png
this is the part that is odd to me. i can guarantee the surface loop is a valid candidate for G2, since all the corners of the surface loop are G2 to each other.
Re: Silk: a NURBS workbench
sure. here it is, had to recreate it.microelly2 wrote: ↑Mon May 21, 2018 1:47 pm can you please upload the grey face, I want to look inside to understand why it is so wavy.
Code: Select all
>>> sel=Gui.Selection.getSelection()[0]
>>> sel
<Part::PartFeature>
>>> sel.BoundaryOrder=[2,1,1]
>>> App.activeDocument().recompute()
- Attachments
-
- Silk_model_144.FCStd
- (547.56 KiB) Downloaded 72 times
Re: Silk: a NURBS workbench
now i got curious whether setting all 3 sides G2 at once other combinations worked better. (this 3 sided hole is clearly a hard problem, and i'm very happy with the G1 result for what it is)
all G2. bad .
G2 on both the straight 'u' and straight 'v' edges .
the untrimmed surface filling with the single G2 on the rounded edge .
a closer look at the untrimmed surface (file attached) now we could do a whole other series of tests to feed the curves in different orders, to see if we can force the untrimmed surface to line up better with the source surface UV, and whether that allows valid results for G2
all G2. bad .
G2 on both the straight 'u' and straight 'v' edges .
the untrimmed surface filling with the single G2 on the rounded edge .
a closer look at the untrimmed surface (file attached) now we could do a whole other series of tests to feed the curves in different orders, to see if we can force the untrimmed surface to line up better with the source surface UV, and whether that allows valid results for G2
Re: Silk: a NURBS workbench
Nice progress.