Subdividing faces

Support Modeling
#1

Ok, yep, I’m new at this. But I have been trying very hard.
I am trying to use blender to model things for cnc cutting. Primarily wood carving.

I am using Inkscape to create vectors around an image that I plane to use as a displacement map. It’s a bird. And I’m trying to capture some of the texture of the feathers.

So, I have my greyscale image. I set up my Inkscape image size. I added the image to the file. I traced the image with Bezier curves to make a path around the image. I deleted the image from the file and saved the path as a standard .svg file.

Open blender, import svg file, fill, make a mesh from the curve, kept a copy of the curve, extruded the face about an inch, turned on 3D printing tab, set Degenerate to 0.00001, set overhang to 90, checked all, Make Manifold, and vwalla’ I have a manifold object that should be 3D printable and cnc cutable.

This is where the problem starts. http://stevemarti.com/from-2d-to-3d-turning-images-into-objects/ is a short tutorial on making 3D object from displacement maps. I can do what he diescribes, BUT, my finished object is just a plane and not an object with thickness a flat bottom and the desired texture on the top surface. It seems that what is happening is only the intersecting areas of the plane and my 3D object are making it through the modifier. I understand that. But Steve shows a different outcome, a flat bottom and some mass beneath the textured surface.

So, Blender Guru also talks about creating a displacement map when creating textures.

Here is my issue, after making my manifold 3D bird with just flat top and bottom faces I want to subdivide the top face so that I can use a displacement map to add a texture to the top face. In edit mode I select the top face in face select mode. I hit subdivide in the tools tab and I end up with only one face. To be precise when select the top face Blender says "Verts:636/1,272 | Edges: 636/1,908 | Faces:1/638 | Tris: 2,540 | Mem: 11.9 MB | Curve001. It’s not a curve it is a mesh. It’s just named Curve001.
After Subdivide Blender says."Verts: 1,272/1,908 | Edges: 1,272/2,544 | Faces: 1/638 | Tris: 3,812 ect…

So, my faces did not subdivide. But my verts doubled as well as my edges. I do not know what Tris is yet.

Is there a step I am missing that will allow me to subdivide the top face of my object?

screenshot01
screenshot01.jpg1238×983 121 KB

Thx in advance!

Robert

#2

If you have a 3-d manifold mesh, like a cube, and you select a single face and subdivide it, you will wind up with n-gons on the other (non selected faces) From what I’ve read you’re best bet is to subdivide the entire mesh (several times) you’ll then need to mark a seam around and unwrap (project from view) and then use a displace modifier on the unwrapped part. Often you will subdivide a couple times to get some goemtry to work with and then temporarily use a subsurf modifers and then the displace, so you can test different levels of subdivision non destructively. save a headache and always keep the preview and render subsurf levels the same. WHen the time comes to export most exporters will ‘apply’ the modifiers, or you can always hit the apply button in the modifiers manually.

#3

Hard to tell without seeing it. Screenshot would be helpful. And Tris means Triangles.

#4

I added a screen shot to my post.

Thx

#5

You can’t subdivide an ngon ( face with more than 4 vertices (it will only create more vertices but won’t slice the face itself, at least not in blender, don’t know about other apps). If you just need dense geometry on top face (and you don’t care about topology), you can try ctrl+T (shortcut) or ctrl+f > triangulate faces and then you will be able to subdivide. But geo density will be pretty uneven so you would probably need to manually add some edges after triangulation to eliminate big triangles.

#6

Yea, I’m playing with the knife tool now. Once I split an area enough the Subdivide tool will work. But, I have to keep checking to see where the new faces will not automatically subdivide and then cut through as many of those as I can .

Thx.

#7

Thanks for the clarification. Now I may see what I can do.

#8

Though not perfectly equal in all areas triangulating faces does allow for additional Subdivides , which just might suffice.

#9

In my opinion doing something like this by hand is not a good idea. Especially for such a simple model. You could probably just use some auto-remesher. Blender has remesh modifier (it’s old and not good anymore but for this simple case could work), there is a free program called “instant remesher”. Your model is basically 1 face extruded on Z axis, so you can remesh the whole model then delete bottom and extrude top face again if you need it to be identical, or just press “F” on bottom faces to turn them into ngon again if you need to.

1 Like
#10

If you are still struggling with it, you can post your file, i could try to do it.
Usually to fill ngon with good topology i would use “grid fill” tool but it won’t work for such a huge ngon with curved borders ( geometry will overlap). You can slice your ngon into pieces and then use grill fill, but then it probably won’t give you even distribution of faces

#11

Thx for the offer. It seems that there is no way for me to apply the displacement map onto just the shape of my bird. Using booleen I never get what I want. So, I am reconsidering my approach. I think I will try setting up a square cube mesh extruded from the surface I have created with the displacement modifier. Finish the model as a cube. And then create a separate model for the shape of the finished model. Use the cube to cut the surface features and then use the shape to create another cutting path for the outline shape of the model. It’s all I can think of at this time.

Thx Again!