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Lip cut?

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Hello guys.

What would be the best approach to cut voxel volume where the upper and lower lips meet? I only need a gentle cut in order to reach the inner mouth area, but the cut must be really thin - I don't want to loose too much of lips' definition.

I have not converted the volume to surface yet.

post-12523-0-94739200-1364232498_thumb.j

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Hello guys.

What would be the best approach to cut voxel volume where the upper and lower lips meet? I only need a gentle cut in order to reach the inner mouth area, but the cut must be really thin - I don't want to loose too much of lips' definition.

I have not converted the volume to surface yet.

You could use the Closed Spline draw mode, hold the CTRL key + ENTER with something like the Build tool. However, if you want to create both an opening and a mouth cavity, use the FFD primitives to create a Cutter object. You could use the Closed Spline draw mode with VoxExtrude to create a precise extension (to create a subtle opening in the lip are).
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It would be a treat to see a video of how you create a mouth cavity using those tools (with a few words on retopo). ;)

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You could try the Pinch tool in reverse (hold down CTRL), with a small brush radius.

Or you could cut the head in half with the Split tool (along the mouth area), then make edits to the bottom and top pieces, then merge them back together again.

Then do the same for left and right pieces.

It's cool how you can actually open stuff up in 3D-Coat and work on it from the inside out.

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Thank you gentlemen. Much appreciated. :hi:

The mouth cavity with tongue, gums and teeth I already had, so it was all about drilling a narrow passage from the outside of the lips to the inside, to link up with the mouth. And it wasn't easy to figure out the optimal solution for this particular mesh.

I was experimenting a bit with the ideas you guys were kind enough to provide me with, plus with some voxel tools. I will post in chronological order what I did and what were the results. Maybe somebody will find it helpful.

First I tried AbnRanger's suggestion and if 3D Coat worked in a slightly different way it would probably be the one I'd use. But unfortunately, three technical problems occurred. First of all, it seems that in order to make that kind of a cut correctly, 3D Coat needs either plenty of voxel resolution or a tall height of the closed curve. 7M tris of the current volume were simply too few, resulting in jagged border and in some places the neighbouring voxels merged with each other due to them being located in close proximity to each other. So I upped the resolution once to 27M and while the merging were no longer a problem, the jaggy look remained. Then, there's the problem with control over the direction of extrusion, which I didn't have. VoxExtrude seems to dig in the general direction of the averaged normal of all affected triangles. The result was a slit aiming slightly upwards, right at the brain (first image). Lastly, VoxExtrude when applied to closed curve generates random blocky shallow extrusions all around the outside of the curve. So a lot of cleaning would be necessary afterwards.

I moved on to try an idea that popped into my brain. "Maybe it could be cut up in surface mode and then connected using the LC_Bridge tool"? With this in mind, I painted holes on both sides (inner and outer) with LC_PaintHoles tool. Then, after holes were generated, with LC_Bridge tool active I went on to painting areas near the border edges on both sides. Applied the changes and...

After 20 minutes of calculations and linear growth of RAM usage 3D Coat crashed - Out of memory. Even though it still had 50% physical RAM left to utilise (second image). I'm not sure what to think about it.

So this idea was a bummer.

Next try: paint with spheres using open curves.

After going through all of voxel tools, I found that VoxSphere seems to be the only voxel tool that, when combined with open/closed curves, use camera aim axis in determining the direction of growth/volume subtraction. The drawback of course is that it draws spheres, so radius means depth thus many uses are required in order to create a deep, but slim slit. Also, I had to hide (with a Cell tool) volume behind the one I was digging through. Throat and the back of the head had to go temporarily, because once spheres began to punch locally through the lips, they were projected on the volumes behind.

Result of the operation can be seen on the third image. Note the jagged surface, but no unwanted voxel deformations outside of the curve.

I had a problem with Timmy's first suggestion, because VoxPinch is not only dependant on brush depth, but radius as well and my mesh simply wasn't of enough voxel resolution for the tool to kick in (with the biggest radius I could afford).

Now, Timmy's Way of Cutting... Very cool! I think it returned the best results.

I did not follow it to the letter, but rather its general premise. Instead of splitting the volume, I entered the VoxHide tool and using a polygonal lasso mode hid the volume from exactly where the lips meet, down to the bottom. This allowed me to switch between halves with upper and lower lips with Invert Hidden command without, all without altering areas of the volume I didn't want to (I've noticed Split tool sometimes leaves little seams when merged back to its volume of origin). Then, I applied some smoothing and move operations to get both parts away from each other. There is some jaggedness in corners due voxels being too close to each other, but I believe this can be corrected later in the surface mode.

Tony, FFD is one cool thing for making things like mouth cavities, but as a cutter object you can also use external meshes, so your cavity can have whatever crazy shape you like it to have. I love voxels. :wub:

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