Mesh.CreateFromBrep(brep) returns too many vertices

[mikity_kogekoge]

Hello,
I’m struggling with a weird behavior of Rhino.Geometry.Mesh.CreateFromBrep(brep).
This function takes a MeshSettings as a parameter, but it also provides an option not providing MeshSettings. That’s what I’m testing.
I attached Rhino file and GH file that reproduce my problem.
There are two Polysurfaces that are identical, only the difference is the location.
The Mesh.CreateFromBrep(brep) returns a mesh with 150 vertices for the first one and 59500 vertices for the second one. Is this a bug? Or otherwise what causes this?
Please somebody help…

Thank you.

meshbrep.gh (3.9 KB)
example.3dm (125.4 KB)

[chanley (Chris Hanley)]

just as a quick test…if you move your geometry to 0,0,0, does it do that same thing? (I know that’s not an end solution, but would confirm or rule out the problem of “geometry to far from 0,0,0 sometimes acts wierd”.)

[mikity_kogekoge]

There is a border at around x=131510, if the polysurface is placed to the left to that line, this problem doesn’t happen.

[chanley (Chris Hanley)]

What are the units of your drawing? If if is millimeters/inches, maybe try setting it to meters/feet and scale the drawing? It sounds like a “too far from origin” thing.
more info here:

Moving an edge on a geometry, far from origo

As was said already, you can either move closer to the origin or use meters. What is going on here is that the math in Rhino 5 uses double-precision accuracy for its operations on geometry but the display mesh is only single-precision. This has been changed for Rhino 6. If you search a bit here on the forum you will find a lot of threads on this. Just one example:

[mikity_kogekoge]

Changing the unit to Meter fix the problem. However, I’m using Large Objects - Millimeters template. That polysurface is roughly 4meters. I don’t think 130m is deemed “too large”. But I agree, probably single precision mesh ghost is still there.