3D Print a Figure: Fixing Non-Manifold Geometry

Photo of Rick Barrett

Instructor Rick Barrett

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  • Duration: 12:53
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  • Made with Release: 16
  • Works with Release: 16 and greater

In this tutorial, you’ll learn how to use the Mesh Checker in Cinema 4D R16 and greater to identify non-manifold edges

In this tutorial, you’ll learn how to use the Mesh Checker in Cinema 4D R16 and greater to identify non-manifold edges, and see the process for fixing this bad geometry to prepare it for 3D printing.

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Transcript

In this 3D printing tutorial, we're taking the farmer from our Unity game and turning him into a 3D printed toy soldier actually, with the way he looks without textures. So, we've already scaled our farmer appropriately and added smoothing via the sub-division surface generator and we also added a little pedestal for him to stand on. What we need to do in this tutorial, is take a closer look at some of the geometry and make sure that it's prepared for 3D printing. A really powerful tool for that is the mesh-checker, which is a little bit tricky to find. If we go qhead and hit shift C, and type in mesh, you're not going to have it show up. But in the commander here, if we type modeling settings, it's actually in the modeling settings that show up in the attribute manager. And you can see that there is actually a keyboard shortcut for that of, shift M. Honestly, the way I usually get to this is through the mode menu of the attribute manager. If you just go down and choose modeling, that gets you to the same place. And this is where you'll find your snap and your quanti settings but there's also the mesh-checking tab here on the far right. And to start seeing the mesh-checking, what you need to do first is enable mesh-check. Now, by default, you'll probably have a lot of these options turned on. And I actually turn most of them off for the purposes of 3D printing, other than non-manifold and boundary edges. These are the things that really matter most to a 3D printer. And right now, you're also not really seeing any effect of the mesh-checker because we don't have a model selected. So, I'm going to go ahead and select our shotgun here. And now, you can see that there are some highlights here. Let's actually solo the shotgun so that we can see this a little bit clearer. I'm just going to choose Viewport solo single here, and that allows us to easily hide everything else, so that we can focus in just on our shotgun. Let's go ahead and dolly in closer to the shotgun here. And, you can see that we actually have quite a few red and green lines here that are marking boundary edges and non-manifold edges. These are going to cause a problem for our slicer. In fact, let's go ahead and just copy the sub-division surface and shotgun here into a new scene and. . . I'm not going to worry about that texture warning. We'll go ahead and zero out all of our coordinates, and I'm going to go ahead and export this as an STL. So, we can see how it looks in a few of the popular slicers. So first we'll start here in Makerbot desktop and if I choose to add file and choose the shotgun, we'll go ahead and move it to the platform and we'll roll in closer to it. It actually looks okay here in this view, however, when I choose to export a print file, and we take a look at the print preview, you'll see that it's getting all messed up here on the barrel of the shotgun and with the pump action of the shotgun. So, this is not going to 3D print properly. And as we've seen before, Makerbot is actually one of the more forgiving slicers. Let's jump in to Simplify 3D and just take a look there. And we'll go ahead and import the shotgun STL file. And we'll go ahead and dolly in closer to the shotgun here. And here, you can see that we're losing the entire barrel of the shotgun, as well as a good portion here of the action. And so, we need to go back Cinema 4D, obviously, and clean up this model. So, we'll go back into Cinema 4D, and let's take a look at how that works. Since we've got the shotgun here in a new scene file already, let's go ahead and just make our modifications here so we don't have to worry about the farmer geometry, and then we'll just copy and paste this shotgun back into our master scene when we're done. So, I'm going to go ahead and pull the shotgun out of the sub-division surface because that's not necessary either for cleaning up the geometry. And we'll just go ahead and delete the sub-division surface for now. So, we'll select the shotgun and hit S to frame it. And actually, we're in polygon mode, I'm going to switch to object mode, S to frame it. And once again, we have textures on, because that didn't carry over when we copied to a new scene file. So, we'll go ahead and turn off textures, and we want to go ahead and turn mesh-checking back on. So, I'm going to go ahead and choose modeling from the mode menu of the attribute manager, and enable mesh-check. Then again, all I'm really concerned with at this point are the non-manifold and the boundary edges so I'll uncheck all the rest of it. And now, we need to take a look at some of these non-manifold edges that are creating these red borders. And most often, non-manifold edges, are the result of geometry that's sort of hiding out back behind the geometry that you can see. It's additional polygons that are interior to your mesh that were created during the modeling process. So, for instance, if we select some of these polygons on the outside of this portion here, go and select that area, and then let's just select this loop as well, and I'm going to go ahead and hide those, by choosing hide-selected. You can see that there is a loop of polygons here that was part of the circle there. And then the support part was created outside of that. So, this circle of polygons is creating non-manifold edges. Now, we can't actually get this to select the loop, probably because of the non-manifold-- or almost had it outlined for a second there. But we'll just go ahead and choose the live selection tool and just go ahead and drag to select these and delete them. We need to go ahead and do that all the way around. So, we'll just keep selecting here and delete and one more there, delete. So, now, you'll see that we don't have a red outline there anymore and if I'd choose select and hide all, there's still no red outline. So, we've cleaned up that particular non-manifold edge. We have a very similar problem here, with this barrel support. I'm going to go ahead and loop-select here, and select this loop and we'll hide that. And here again, you can see that there's additional polygons that have nestled up inside of that support. So, we'll go ahead and select those, both here on the bottom, as well as up here on the top, just holding down shift and painting with the live selection tool-- oops, that's the move tool. And now, hit delete. And you can see that by taking away those polygons, I lost my red outline. While we've got that support hidden, you can see that we've also got non-manifold edges down here inside. So, we'll go ahead and select this row of polygons or this circle of polygons and delete those. You can see here that there was actually an extrusion down from there. So, that was blocking things off. Now, these boundary edges can be an issue as well but for now, we're just going to focus on cleaning up the non-manifold edges and see if that gets us far enough. So, I'm going to go ahead and unhide all, and we'll go ahead and take a look. And it looks like we have taken care of the non-manifold edges now on the front of the shotgun. Let's go ahead with a look at the back. And it looks like we have a very similar issue going on here around the top support here. So, I'm going to go ahead and loop-select this portion, and we'll hide that. And, once again, we have an interior loop of polygons that needs to be deleted. So, I'm going to go ahead and select the live selection tool and we'll just paint to select and delete. And we'll go around here to the other side and do the same thing. You do want to make sure that your mouse is over the Viewport as you delete, and it looks like we have one more here to clean up. So, once again, that created some boundary edges that may or may not be an issue but we're not going to worry about those yet. We're going to go ahead and just stick to fixing the non-manifold issues. So, we'll go ahead and unhide all. And now we've got another one down here, so I'm going to go ahead and select this portion and we'll hide that. And it looks like here, we've got some spots to clean up right around here. So we'll go ahead and select those polygons, then hit delete. And it looks like that fixed that part of the issue. There's another non-manifold edge, right in there. We'll see if we can figure out what's going on with that, go ahead and hide these polygons as well. And it's really kind of hard to tell what our problem is here. I think it must be these two polygons here. So, let's go ahead and try deleting those. And yeah, that cleaned up the non-manifold. And so we've got again, some boundary edges, we're not going to worry about yet. We're going to just focus on the non-manifolds for now. So now we'll go ahead and unhide all, let's go ahead and go back into the modeling settings. I'm going to use the shortcut, shift M. And here we can see, we still have 16 non-manifold edges. So, let's go ahead and select those. And it looks like some of them are up here on the top of the sight. So, we'll go ahead and select the top portion of the sight here, let me go back into polygon mode, and we'll select this loop as well as this loop and we'll grab these polygons here, sort of get the top of the sight. And we'll go ahead and hide selected. And you can see here that we have some additional polygons under the top part of that sight. So, we'll just go ahead and select these and delete them. And now we will go ahead and unhide all. We'll go ahead and hit shift M again and see where we're at. Now, we just have four non-manifold edges. I'm gonna go ahead and select those and we'll see if we can find them. It looks like they're down here by the trigger. So, we'll go ahead and come down here to the trigger portion and I'm going to go ahead and choose the polygon tool and we'll go ahead and select those polygons there and hide selected. And once again, here we have just an additional polygon hiding out. So we'll go ahead and delete that. And once again, we'll unhide all. And you can see now that we have zero non-manifold edges. So we have cleaned up all of the non-manifold issues that we had here with this model.
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