I noticed that “Quad remesh” struggles a lot with the so-called “mechanical geometry”, such like pipes, simple boxy shapes for CNC-milling and other objects consisting sharp edges and holes. Is there a possibility for the tool to get any better in the final release of Rhino 9?
Can you send the in the damaged meshes?
Sure, here are 3 of the pipes that fail to be converted properly by the “QuadRemesh” tool. They were extracted as render mesh from NURBS models made by me several years ago in Rhino 7.
QuadRemesh these meshes will fail.3dm (315.8 KB)
My customer just wanted to have these reworked as hard-to-copy NURBS models, i.e. meshes converted with QuadRemesh to SubD, then the SubD converted to multiple NURBS patches again. Then export the worsened NURBS geometry as STEP for other customers with Solidworks, Catia etc.
The goal is to stay visually close to the original NURBS shape (for CNC-milling purposes) but make the geometry unusable for a quick reverse engineering, such like destroying the ideal cylinder shape and making it a non-circular profile with variable radius. Likewise, the original perpendicular cap surfaces at either end of each pipe should be slightly off (or rounded) to not allow an easy extraction of the cross section surfaces.
Many of the CNC-shops try to steal/copy chassis design, so one way to prevent that (or make it harder) is to provide inaccurate NURBS geometry in the sense of bad enough to prevent extracting of the cylindrical shapes.
Splitting the cylinders with multiple isocurves and shrinking is not a solution, because these could be merged into a cylinder again. Changing the degree and adding random knots to destroy the ideal round profile is slow, because that would force me to rework hundreds of pipes manually due to the many holes and extra details at either end of each pipe.
The “QuadRemesh” worked fine on some of the simpler pipes, but any hole or more complex end resulted into the weird geometry bugs shown in the videos above.
I think the high aspect ratio if some of the faces is not ideal for quad remesh. I get a result after shrinkwrapping the meshes.
I also tried various settings of “ShrinkWrap”, but I could not find an universal solution. Some pipes were still producing random geometry that has nothing to do with the input mesh.
Pipes that are not perfectly horizontal or vertical receive ugly output from “ShrinkWrap”.
Applying “QuadrangulateMesh” before “QuadRemesh” gives slightly better results, but the geometry is still way off in random areas.
If I use very fine settings for the “ShrinkWrap”, that will not let me preserve the sharp edges at either end of the pipe, as well as around the holes. Note that the sharp edges are needed for CNC-laser cutting, but the goal is to make the NURBS geometry bad enough to prevent easy reverse engineering. This is why I wanted to use “QuadRemesh” with the “SubD creases” and “Interpolate SubD” options directly to the extracted render mesh to keep both ends as close as possible to the original geometry.
When I apply “QuadRemesh” to the result of “ShrinkWrap”, the geometry loses the sharp edges, and it gets highly distorted in some areas, despite that the input mesh geometry is a perfectly straight extrusion.
If you look closely on the tiny hole at the left side, you will notice that the resulting geometry is distorted. I already tried to convert only the outer shape, but the results were no better.
When I tried this on various pipes a few months ago (the videos were captured on 21st July 2026), I got different results even with the slightest change of the settings, so it’s a really time-consuming process to try thousands of different settings in an attempt to convert about 100 pipes.
remesh in meshmixer (top) (remesh with target edge length) (also meshlab or others can do this)
quadremesh and use Adaptive Size 100%
best - the meshes seam to come from other cad - optimize the export - import pipeline, use other file format or other meshing-parameter in the exporting program.
kind regards - tom
This particular pipe is not so hard to convert to SubD due to the larger 4-sided holes and the smooth ends. However, other pipes with more complex ends and smaller holes cause the biggest issues with the converting to SubD.
Anyway, thank you for your time to all. I no longer need this functionality as it was an old task. But it would be nice if the “QuadRemesh” tool gets better in the future, because I can imagine that many people would like to 3d print some mechanical parts that were imported in Rhino as a raw scan data with ton of polygons.
