Importing CAD Models into Cinema 4D: Fixing common mesh issues in Cinema 4D

Photo of Rod Ross

Instructor Rod Ross

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  • Duration: 06:16
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  • Made with Release: 17
  • Works with Release: 17 and greater

In this tutorial we use the mesh checker and optimize to find and fix problems with import CAD geometry.

In this tutorial we use mesh checker to find problems with geometry imported from CAD files. We go through each step of the mesh checker and discuss ways to fix these issues.



- In this tutorial, we'll be talking about fixing common mesh issues. We'll be using the Mesh Checker in Cinema 4D, a tool that alerts us to possible mesh problems so that we can fix them. To go to the Mesh Checker, I just go to Mode, and then Modeling. Then, I'll check the box for Enable Mesh Check, and I'll go ahead and lock this to keep it on the Mesh Checker. Then, I'll go click on my drill, and I'll middle-click to select all of the parts. As you can see, Mesh Checker has found a lot of possible problems with my mesh. Fortunately, we may not need to correct all of these issues for it to render correctly. I'll go to another file so I can explain what Mesh Checker is checking for. So I'll go to Window and Mesh Checker. Here are some examples to give you a better idea of what Mesh Checker does. First, I'll go to Mode and go to Modeling, and I'll turn on Enable Mesh Check. The first one we'll go to is Isolated Points, so I'll select that. It might ask you to zoom in. I'll go back to Mesh Checker under Mode, and then Modeling, and I'll lock it this time. So for my isolated points, I see that I have 105. I can just select those and delete them, and now those are gone. Those can happen if you delete the polygons, but don't delete the points. So let's move on to the next one, which is Edge Points. I'll hit my S key, and as you can see, these points do not help define the shape of this polygon at all. But if I were to select these points and move it, now you can see that the warning goes away and these points are contributing to the shape of this polygon. For Edge Points, there's also a threshold and you can change the angle to, say, 90 degrees and that would only show the points that you want warnings for. Now, we'll go on to Complex Poles. As you can see, this is giving us a warning for this point in the middle. This is basically how many edges are going into that vertex. Down here, underneath Complex Poles, there's an edge count. If I were to change that to seven, you can see that the warning goes away. This could be helpful for you if you wanted your model to be all quads. Now, I'll change this back to six, and we don't really need these edges. So I'll select those, and I'll right-click and Dissolve, and now the warning goes away. The next one we'll go to is Non-Manifold, and I'll give you an example here. Let's say that I'll go to Edge mode, and I've selected these bottom edges here. I'll go to Scale, and I'll hold my CTRL key down and drag these out. Now, I'm getting a warning for Non-Manifold, which you can see underneath here. Now, if I were to select this polygon and delete it, the warning would go away. That can be a problem that you might run into while modeling. So the next one we'll go to is Boundary Edges, and I'll hit my S key. This is just basically outlining the boundary of your object. In this case, it's a hole. So we could just right-click and Close Polygon Whole, and that would solve that problem. The next one we'll go to is Bad Polygons. For this, I'll uncheck Not Planar Polygons so we can see this better. This warning for the bad polygons, you'll see when I move this point. If you have two congruent points, I'll turn on my snaps and I'll move this over, and now this is giving us a warning for bad polygons. I could just select these points and delete them. In that case, that would solve that problem. Now, I'll go to Not Planar Polygons. I'll hit my S key to zoom in, and if I go to my Point mode I could just select one of these points. If I start dragging it up, I need to recheck Not Planar Polygons, and you can see once they pass this threshold of 15 degrees, it'll give us the warning. So if I drag this back down, it's okay here. I can set this threshold higher if I want. But that is to show your not planar polygons. It may not necessarily be a problem in every case, but it's giving you a warning to alert you to a possible problem. That gives you a good overview of what the Mesh Checker does and what it looks for. Keep the Mesh Checker in mind when you bring in CAD models, because they are prone to having a lot of problems with Mesh. This can alert you to the problems, so you can solve them. Now, we'll go back to our CAD model. So I'll go to Window and Mesh Checker Drill, and I'll go to Mode, Modeling, and I'll lock this window. So for the isolated points, I'll go ahead and select these, and I'll just delete those. It's a good idea to go through these one at a time, and then you can concentrate on that specific issue. If you notice that your model is rendering okay, you can just go on to the next issue. But if you see you have a render issue with your model, the Mesh Checker would be a good place to start to solve that problem.
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