Offset Test.3dm (363.7 KB)
The attached file includes a set of joined surfaces and two curves projected on the joined surfaces. I need to offset each of the curves by 1mm outward. The process does not work on the joined surfaces. What steps are needed to transform the surface such that offset curve on surface will work?
Offset Test.3dm (343.3 KB)
I added a CAD file with the flat curves in addition to the projected curves.
Hi @ronald1,
once you explode the projected curve and join the curve pieces together per surface, the _OffsetCrvOnSrf command works using 1mm. I guess it gets confused if the curve is not fully on the surface.
_
c.
Hi Clement,
I gave that a try. The first thing I noticed after exploding the curve into many small segments is that my surface is a mess. Projecting the curve onto the messed up surface created a messed up curve. Is there a tool for cleaning up the surface? Also after joining the elements of the exploded curve, I attempted to offset the curve on surface by 1 mm. It still failed. Perhaps I did not understand what you meant by "join the curve pieces together per surface. I just joined them all back together.
Should I have merged the surfaces instead of joining the surfaces? If so, what parameters should I use with mergesrf?
Hi @ronald1, that depends of what you’re after. I’ve thought that the v-shaped groove between the two large surfaces is intended. In general you should only merge surface when they are continous at their meeting edges and have the same amount of points along that edge.
I see 4 surfaces joined into one polysurface. If course if you project curve on this and explode it will result into multiple pieces where the curve crossed the edges of the surfaces.
If you mean to get rid of the v-shaped inner two surfaces and aim for a continuous transition between the two larger ones, remove the smaller surfaces then use _MatchSrf eg. using Continuity set to Tangency, AverageSurfaces checked, Match target isocurve direction. Then reproject the rectangle.
I’ve meant that you only join the curve pieces together which are on one of the surfaces not on all four. Once you do this the _OffsetCrvOnSrf worked here, testing with Rhino 7 and 8.
_
c.
Hi Ronald - OffsetCrvOnSrf works per surface, that is, per face on a poilysurface. So I would not say you ‘should’ merge the surfaces, only that you just need to do the ofsetting in parts, as things currently stand - nothing wrong with that, I think, except the inconveniance.
-Pascal
Having learned a bit more about use of Rhino, I rebuilt the main top outer surface. Now it would help if I could merge the mirrored sections into a single surface. Unfortunately “Edges are too far apart to merge”
What does this mean? How can I fix the edges so that they are not too far apart, or can I adjust the mergesrf parameters?
MergeSrf Too Far Apart.3dm (417.7 KB)
Hi Ronald - CrvDeviation or EdgeContinuity (Position) will show the edges to be .016 apart. Use MatchSrf for Position, wirh Average set to pull them together. Then MergeSrf - set Smooth=No if you want to maintIain that slight crease.
-Pascal
Hi Pascal,
Our students are excited about the merging of upper and lower main body external surfaces. Your guidance worked well for merging and rebuilding upper secti
Main Body Surface Merge.3dm (241.9 KB)
ons and lower sections, but now we are stuck with merging the upper an lower sections. I have not been able to use matchsrf bring the front edges together.
Hi Ronald - UntrimEll, MatchSrf for Position Average surfaces checked, presumably. Note the match will split the kinked single surfaces back into two joined faces, so Explode then merge everything one pair at a time - side to side, then top to bottom. - Smooth=No to keep the creases. Smooth=Yes ( with a smoothness setting between 0 and 1) to round them off. When done it cal all be one surface.
But… why are you mergeing? What problem does it solve?
@ronald1 - fwiw, I don’t know what the design requires, but the underside has a pretty strong reversal in curvature
-Pascal
The process of making the surfaces into a form that can be merged is helping the students recognize strange features, and that will help them develop good design approaches.