Question about booleans and cleaning geometry

[cjzbc]

Apologies if this is an amateur question: I’m working on some bas reliefs for 3d printing and the easiest way I’ve found to do it was to use the old transform tool with backface mask applied, and then live booleaning the back panel out. On my latest mesh this has given me some difficult geometry on the back face that I can’t get rid of. On other models I’ve duplicated, zremeshed, and projected the original model and gotten good results but with this one I lose too much detail.

Is there a way to fix this or just work around it? I guess since it’s on the back face I could 3D print as is but I’d like to clean it up if that’s an option.

Here are some screenshots for reference, thanks in advance for any help!

[Spyndel]

Hello @cjzbc

Re: Cleanup. Cleaning up defects like that on a flat surface is pretty easy, although it involves a few steps.

1. Because your mesh doesn’t have a lot of fine high resolution detail, you have a bit of flexibility as to what stage in the history you want to project from. Depending on the results of step #2, you may wish to mark that stage for projection instead, but for now, Ctrl-click on the current “blip” in your undo history timeline (on the top edge of the viewport) to mark it for projection.

2. Dynamesh at desired resolution. Because of your chosen process, you probably have a lot of complicated overlapping interior geometry. Dynamesh will get rid of that, and it might even close the smaller holes for you on the bottom. If the holes are still there, use the Planar brush in Alt mode (alt-click on a flat portion of the surface with the brush, then brush over the holes to fill them up to that level). You can use the Clip Curve brush to completely re-flatten the bottom of the mesh. Dynamesh again to clean up any overlapping geometry on the bottom.

• If you were able to Dynamesh at high enough resolution and are happy with the level of detail on the hat, you may wish to instead mark this stage of the mesh for projection. This will have the benefit of not including the original holes in the projection, requiring less masking or cleanup when you project.

3. If working for print this step is technically optional, depending on how much detail you retained through the process. If working for print you can simply decimate the Dynameshed hat and export for print. If you’d like a better quality mesh, then ZRemesh the hat at the desired settings, subdivide it sufficiently to hold the incoming detail, and use the Tool> Subtool> Projection > Project History function to project the detail from the previously marked state onto the new mesh. You may have to increase the .dist slider if there are gaps in the projection.

• Note that if projecting from the mesh in a state when the holes were still present, you would need to mask the bottom of the mesh before projecting to keep the holes from being projected onto the mesh as well.

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Re: Extrusion

I recently composed a crude tutorial for someone doing similar work, and some of that may be useful for you as well. It involves using Transpose Extrusion AFTER performing a Live Boolean operation:

"Lift surface" brush that preserves details?

You may benefit from a multiple subdivision level process, and working on the figure as a separate 3d object. This will open up many options for you. Multiple subdivision levels are a feature in later stage sculpting, not something to be feared. One of the perks of having a mesh with a clean, low poly base and multiple levels of subdivision, is that you can sculpt on your mesh at different levels of resolution simultaneously. The mesh performs differently at lower poly than it does at high po…

Good luck!

[MattBon]

I used to find the same issues trying to add plinths in ZB.

I sculpt bas-reliefs for coinage, which don’t need to be manifold as they go for CNC/ laser, so this might be a totally useless input!

I work from a template plane in ZB that has no back - a backface mesh just gets in the way, and has to be clipped off anyway.
However, if I need to add a plinth for whatever reason, I do this…

Once I’m done with the sculpting, I GoZ to Blender (where I scale to size, add circumference lettering etc.).
Ctrl-A to fix scale, tab to edit mode.
Select boundary loop of vertices, which picks up the outside profile of my mesh.
Hit S,Z,0 to align all those verts to the same plane, then drop them the required distance to give me my ‘platform’.
Create a face from those verts, and my object is solid.
I export to obj, and Blender will triangulate that big backface plane on the way out, so job done.