Extruding closed curve making jagged edges

Rhino Rhino for Windows
1

I am trying to extrude a closed curve so that I can create a solid .stl. When I am extruding the curve it looks all jagged. When I open the .stl in Makerbot if is also jagged. ***This is not just a rendering issue for the mesh it actually exports jagged. Check out the attached screen shot. Notice the2nd from bottom left image with the red dot on it. You will see that around the edges there is a jagged shape escaping.

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Why is my line not remaining the smooth curvature? How do I fix this?
Thanks!
Cameron

2

Hi Cameron - It looks like your objects are very far from the World origin (Coordinates shown in the bottom left of the screen grab) If possible, move everything closer in and it should look better. Use ClearAllMeshes to force remeshing after the move, if needed.

-Pascal

3

Not familiar with the world origin. How do I move everything over there?

4

Try move, select all you geo, OSnap to some part of it (or a specific point you want at world 0), for the point to move to type in w0 (enter), then you can use ZEA (zoom extents all) to find everything again.

Sam

5

You all rock! That did it. You are my new best friends! haha j/k

For real though. Thanks for the help. So I can learn why…‘why’ does the proximity to the world ‘0’ affect the geometry?

Thanks again,
Cameron

6

It has to do with floating point representation in a computer. Most of the geometry is represented by double precision floating point numbers, but meshes by single precision floating point numbers.
As numbers become larger and larger, the gaps between consecutive floating point numbers becomes larger too. If you are far from the origin, these gaps can become of the same magnitude as the size of your object. Then you start to see jagged edges.

7

Menno. Thanks!

Cheers everyone,
Cameron

8

Beginner tips FYI

I see this problem all the time in my class. Try these steps when you start any new file:

  • Pick your units FIRST (avoid scaling later)
  • Determine your ‘overall’ size by drawing a rectangle (prevents things being huge or tiny)
  • Build on origin (easier for mirroring, etc.)