I may be asking something obvious but I’ve not managed to find anything in searches or on the forums for this:
Essentially what I’m trying to do is map a selection of curves (delaunay mesh-ish) from the area between an outer square and inner circle, to the same area, but with a larger inner circle. In real life the pattern’s not that simple, and neither is the whole square-circle thing, and there are engineering tolerances…etc, but hopefully the image gives you the basic idea of what’s going on.
The problem I’m having is when I try to map from one surface to another it’s creating too much distortion (bowed edges along the straights of the square…etc.)
I’ve tried mapping the pattern from old to new surfaces in straight rhino with flow along srf, and in grasshopper with closest pt and eval srf (image attached).
I’m pretty sure the problem is, as illustrated on the sample surface (image attached), that the parameterisation of the surfaces is not all that even.
To even it out I’ve tried building both surfaces using exactly the same method, with the same number of control points in U and V, with the same distribution (which is even in XYZ cartesian space), on both starting and target surfaces (which I usually do for flow along srf anyway). Both flow along srf and the GH method I used (also in attached pic) still come out with quite a lot of distortion, though flow along srf seems a little less distorted so I guess it’s doing some form of rebuilding or reparameterisation within it.
My workaround so far (as rebuild makes it too different a form) has been to break up the surface into a few hundred smaller segments, all constructed in the same way and map them all (essentially kind of manually resampling it so the distortion within the segments is physically smaller), but this is a pretty inelegant way to do it, and still requires a fair bit of cleanup as it still creates some edges that don’t quite line up.
Apologies for the long post but in essence, if anyone knows how to do a flow along srf type thing but to actually even out the reperamaterisation, either by doing something with the definition, constructing the reference surfaces differently or even at a push some scripting (I have an extremely hazy grasp of python in rhino) that would be massively helpful.
Apologies also that I can’t post up actual images or files but unfortunately it’s one of those client confidentiality things on this project.
Thanks again to anyone with the patience to actually read all that!