Mesh splitting

I am trying to apply texture to a model for 3d pritning.I used the displacement mapping to get my texture as a mesh, but I need to trim the mesh and I cant seem to get rhino to trium the mesh.I have tried the extractnonmanifol and extractduplicat functions, but the mesh still will not split.I tried uploading the rhino file, but I keep getting an error message.
The file size is 256 mb.I assume that is wht it wont upload.
SO is there a way to post the file so somewone can see what I am doing wrong?

Carl

You could upload the file to Google Drive or a similar service and then provide a link here.

Then I could look at splitting the mesh with my Python script. It works in many cases where the Rhino Mesh tools splitting functions fail. The script uses a closed curve in the top view to define where to split, trim or make a hole in the mesh

Regards,
Terry.

Thanks Terry I will do that later on. I have the bottom hull of a spaceship and I want to put a texture on the surface of the ship.So I used the displacement map to make a texture shell.The texture from the shell needs to be trimmed in certain areas and that is where I am failing .I can always just print the shell with a smooth surface and then apply texture with bondo if it doesnt work. Due to the size of the part it takes rhino a while todo any modifications to the texture mesh.Once I have the mesh trimmed to fit the hull I want to merge the shell and the hull into one mesh that I can then 3d print.

Carl

Hello - please export the mesh you want to split and the cutters and post just that, or send to tech@mcneel.com with a link back to this topic in your comments; if the file is still very large, please upload to www.rhino3d.com/upload to my attention.

-Pascal

Have you tried to Unweld with 0 degree angle tolerance?

So here is the base which I want to apply the texture to

Here is the texture mesh

Here are the cutting planes necessary to trim the texture from the edges of the mesh.This is what I cant get to work.I need to trim the mesh flush with the edges of the base and then merge the mesh to the base so I can pritn the base with the texture on it![base5|690x302]

here is the dropbox link for the rhino file

Hello - the mesh in your file is displaced so much that any trim or intersection is going to be a mess - try setting the white point in the displacement control to say .25 rather than 1.0.

-Pascal

thanks Pascal.What does the displacement control actually do.I thought the larger number would make the pattern more pronounced and I wanted a rough surface not a very subtle texture

Carl

Hi Carl - the displacement works off of the grayscale of the image - white= max displacement, black = none. In this case, the max makes a jumble:

-Pascal

I reset to 0.25 and got a really nice texture.I actually dont even need to trim this.it looks fine on the ship (ET spaceship). Now how do I merge this with the base piece .Do I need to extract the rendermesh from the closed solid polysurface base piece and then merge the meshes to creat a singl mesh that I can export and print?

Hello - yeah - that takes some doing - basically to nee to make the rest of the part a mesh - then stich up the offset mesh to the rest. I’ll see if I can make an example.

-Pascal

I usually do this with mesh>repair tools>patch single face to make “bridges” between the two parts in critical areas like corners, areas of high transition etc. then I use mesh>repair tools> fill hole to fill in the holes between the “bridges”

then fill holes-
mesh_fix

In your case many more bridges will be helpful and you may want to use fill all holes in the mesh repair tools. then show edges and check for naked edges.

additional tip… if you have a. messy problem in an area, sometimes deleting the whole area to make a bigger hole (although counter intuitive) and using fill hole is easier than trying to repair a messy spot.

Yeah, this - what @theoutside says … only in your case the displaced mesh is pretty massive and difficult to work with - you might want to ExtractMeshFaces around each opening to a separate mesh before you start working - hide all but those two bits.

-Pascal

1 Like

OK so what I am reading sounds like this is not going to be a case of just doing a union of the 2 meshes!! I think because of the number of cutouts in my model would make this really challenging to do.I guess I would need to bridge the 2 meshes at all of cutouts in my model in merge the meshes at those edges. Is there an alternate way to get surface texture on a part for 3d pritning.I looked at the heightfield function but not sure if that would work.

@pascal are you saying extract the meshes for the walls of the openings and then try to merge those with the texture mesh first and then merge that combination to the rest of the base piece?

Carl

Hi Carl - I would ExtractRenderMesh on all the parts - parts that should be joined (apart from the textured object) should be joined before extracting the meshes. Explode or ExtractMeshPart the meshes to get at the relevant parts individually if needed but having the surfaces all joined up will ensure that the meshes join back again seamlessly.
Once that is done, I would do this:

  1. Isolate the textured mesh.
  2. ExtractMeshFaces around each opening. The goal is to get just as few polygons from the textures dome mesh as is convenient as a separate mesh around each opening, then hide the rest of the textured object - it is massively dense, and bogs down the display etc. All of this will be joined up again later.
  3. Extract the mesh for each opening from the rest of the model the tubes etc.
  4. Isolate each pair (textured mesh stuff from around the opening and the mesh tube or whatever you want to stitch it up to on layers.

All of this is the make the operations more manageable - mesh operations on the huge dense mesh will be painful and eat up Undo memory very quickly.

Now, one pair at a time, proceed as Kyle suggests to bridge across - it may be worth pulling the tube mesh edges back just a little to make a clear separation all the way around .

-Pascal