Checkmesh offsetmesh solid checkbox fails to make solid just 2 meshes

Rhino Rhino for Windows
1

Hi
I imported a lampshade which is a mesh with zero thickness. I then used offset mesh to create a thickness by checking th solid box. However, I get two “parallel” meshes that are not joined but are separated by the distance I entered in offsetmesh.
I used checkmesh and checknewobjects but no problems with the mesh are shown.
The lapmpshade was originally a .blender file but I used an online converted to turn it into an .stl
I’ve been fiddling around late at night trying to get this to work and its frustrating.
Please help.

Here is what I get suing the check diagnostic:
This is a bad mesh.

Here is what is wrong with this mesh:
Mesh has 7124 degenerate faces.
Mesh has 137336 non manifold edges.
Mesh has 104164 duplicate faces.
Skipping face direction check because of positive non manifold edge count.

Important things to consider with this mesh:
Mesh has 112377 pairs of faces that intersect each other. Although this does not
necessarily mean that the mesh is bad, it can cause problems if you’re doing mesh boolean operations with it.

General information about this mesh:
Mesh does not have any extremely short edges.
Mesh does not have any naked edges.
Mesh does not have any disjoint pieces.
Mesh does not have any unused vertices.

ID: 7bdbabb5-7611-47d8-86b1-f882ed908769 (20)
Object name: Rhinoceros Binary STL ( Aug 10 2015 )

Layer name: Default
Render Material:
source = from layer
index = -1
Geometry:
Valid mesh.
Closed double precision polygon mesh: 354664 vertices, 207018 polygons with normals
bounding box: (-3.08832,-2.67868,0.0189817) to (2.97868,3.38824,5.0468)
Geometry UserData:
UserData ID: 17F24E75-21BE-4a7b-9F3D-7F85225247E3
Plug-in: c8cda597-d957-4625-a4b3-a0b510fc30d4
description: ON_Mesh double precision vertices
saved in file: yes
copy count: 1

This is a bad mesh.

Here is what is wrong with this mesh:
Mesh has 686 degenerate faces.
Mesh has 137336 non manifold edges.
Mesh has 104164 duplicate faces.
Skipping face direction check because of positive non manifold edge count.

Important things to consider with this mesh:
Mesh has 39361857 pairs of faces that intersect each other. Although this does not
necessarily mean that the mesh is bad, it can cause problems if you’re doing mesh boolean operations with it.

General information about this mesh:
Mesh does not have any extremely short edges.
Mesh does not have any naked edges.
Mesh does not have any disjoint pieces.
Mesh does not have any unused vertices.

ID: 0e5eda96-a5ee-4987-a808-1e00d85809e0 (19)
Object name: Rhinoceros Binary STL ( Aug 10 2015 )

Layer name: Default
Render Material:
source = from layer
index = -1
Geometry:
Valid mesh.
Closed double precision polygon mesh: 378910 vertices, 207018 polygons with normals
bounding box: (-3.38831,-2.97868,-0.175953) to (3.27866,3.68823,5.34677)
Geometry UserData:
UserData ID: 17F24E75-21BE-4a7b-9F3D-7F85225247E3
Plug-in: c8cda597-d957-4625-a4b3-a0b510fc30d4
description: ON_Mesh double precision vertices
saved in file: yes
copy count: 1

2

@rdsk,

from your description and the check result it sounds like you did the offset of all tirangles individually. If you import your mesh as stl, check the mesh for naked edges and unwelded edges first using _ShowEdges command. If you see edges in areas where the mesh should be fully closed, try to use _Weld with a higher angle (eg. 180) before offsetting the mesh. Usually the solid rim part is build at the naked edges after the offset has been performed.

Note that all this is better answered if you can post the mesh.

c.

3

Hi Clements
These amazing stereographic lampshades .blender are at
https://www.copy.com/s/t%3AssvpahXVKzeb4lre%3Bp%3A%2FLampshades.blend%3Boid%3A13389
My stl conversion is at
https://drive.google.com/file/d/0B3_qq9691bVuZE82SU4ycVhzTXc/view?usp=sharing

Thanks for your instructions which I’ll try. However this is a very intricate pattern and large file 20MB.
If you could test your solution would be appreciated but the file is very large to download.
Rupert

Credits to Mr Cole for his orginals:

4

Hi Clement
I tried _ShowEdges but it didnt find any naked edges but the whole thing was non-manifold.

Do I need to weld the non-manifold. Out of my depth here!

Rupert

5

@rdsk,

i did try it with the blend file as the stl was totaly broken. My guess is that the converter you used to create the stl does not deal with the modifiers which where applied in blender. Even the meshes in the blend file did show a few errors. There where modifiers applied to thicken the lampshades which i removed before exporting the meshes as obj. These where then imported into rhino.

(The red lampshade has still errors present in the original blend file, all other look fine, but check still shows some problems, except for one). I guess to track down the errors in the red lampshade, you will have to find out in which version of blender the file has been created, then download it and see if it looks any better)

The Rhino file contains all 4 shades as mesh: Lampshades_Meshes.zip (6.1 MB)

c.

6

Thanks Clement.

How did you fix those meshes? Is there a better converter to use?

I printed the first lampshade and it works brilliantly.

I now wish there was a way to automatically create the stereographic oattersn. It would be fun to have kids sketches etc eg winnie the poo to help kids sleep

Thanks so much as I was about to give up.

Rupert

7

Download and use Blender, then work there to get non solid spheres. All i did in Blender was selecting all vertices in edit mode, then using Remove Doubles command. Then´ve exported the meshes as obj format.

In Rhino, i used Weld, UnifyMeshNormals etc. [quote=“rdsk, post:6, topic:28852”]
I now wish there was a way to automatically create the stereographic oattersn.
[/quote]

try below script to create your own nurbs lampshades in rhino. Use the script with the example scene so you can see how it works. Once the curves an the floor are projected to the sphere, split the sphere surface with them and delete the holes. If you render with the rhino renderer, you might see how the lampshade works…

LampShadeProjector.py (1.9 KB)

Example scene: LampShades.zip (6.4 MB)

c.