Tech Tip - Curvature Continuity
Вставка
- Опубліковано 21 вер 2015
- Presenter: Jesse Sprague
www.cadimensions.com/products/... During this Tech Tip, we are going to talk about curvature continuity. As we mentioned, to see last week's tip on the Zebra Stripe and Curvature tools, go here • Tech Tip - Zebra Strip...
That is a really good demonstration, I have used it a bit in the automotive industry but these days the stylists use alias for A class and we draftspeople create models from their surfaces but usually only use tangent fillets as people don't generally don't examine an engine bay surface.
Class A mean the 1st and 2nd derivatives match along with the 'K' curvature radius, specifically of the osculating circle of both segment endpoints.
Thanks for the video
so what should i tell you jesi ????
03:50
WRONG
G0, 1, 2, 3 isn't the same as C0, 1 2 3
G continuiey refferences geometric continuity which is what you are messing about with
C continuiry reffers to parametric continuity
these surfaces are parametric in that they're essentially a function that you input 2 parameters in (usually t and s) and you get a set of 3 values (xyz) which is the point in space belonging to that curve. they are functions mapping 2d space into 3d space f(t,s) => (x,y,z)
but you can imagine as you increase either t or s by a strady amount the point you are sampling will move along the 3d surface. C continuity reffers to how that movement occurs. C0 continuity just means that as you cross the 2 surfaces the t parameter doesn't "jump" : there are no values taken twice and no values skipped during the transition.
C1 continuity means the sampled point doesn't change speed when crossing the 2 surfaces. C3 continuity means the parameter doesn't change accelerationwhen transitioning between the 2 surfaces.
you could see this when you try to export the NURBS as a triangle mesh: the middle of the surface will have vertices which are sampled by taking the function and inputting incremented values and the output should be a grid closely smoothly the curved surface. if you try to export the 2 merged surfaces that have C1 continuity you'll see a change of "density" in the mesh (one surface will have more triangles and the other will have way less and there's a clear seam between them ) If you export a C2 or C3 continous set of surfaces, in the triangle mesh you'll notice a gradual increase or decrease of triangle density when going across them, with the C3 being a lot smoother transition than the C2
Please note that this is completely separate from geometric continuity: you could only have a sharp G0 turn and still have complete C3 parametric continuity
How did you create a G3 surface in Solidworks?
This was a standard 3 point spline that had been adjusted by hand to create a smooth transition. However... keep your eyes peeled. There may be some new tools in this area in a release of the software coming soon!
I like that like.
❤️