Importing CAD Models into Cinema 4D: Using Zbrush to quickly retopologize and UV Map a CAD Model

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Instructor Rod Ross

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  • Duration: 07:30
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In this video we demonstrate how to retopologize a CAD model using Zbrush remesher and UV master to setup UV’s.

In this video we start with a CAD model we imported into C4D. Then we go through the steps in Zbrush to retopologize the model using remesher. Once the model is has been retopologized we use UV master in Zbrush to setup the UV’s.

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Transcript

- In this tutorial, we're going to take a look at ZRemesher and ZBrush. There may be times when you need to retopologize your CAD models, and ZRemesher is a quick way to do that. Later in the tutorial, we'll also take a look at UB Master in ZBrush, and that's a quick way to set up your UV maps. The model on the left has been imported from CAD, and the one on the right is that same model taken into ZBrush and retopologized using ZRemesher. You'll notice that the mesh is denser, but the topology is much better. Normally, when we think of ZRemesher, we think of organic models. But with a couple extra steps, it does a pretty good job with hard surface models also. I'll go to my other file. Then, we'll go through the steps it takes to retopologize our CAD model in ZRemesher. Now, the first thing I'll do is click on the object. I'll go to Script, User Scripts, GoZBrushFromCinema4D, and then ZBrush will open. I'll click on Hide to close my browser and get it out of our way. Then, I'll drag across the screen to place the object, and I'll click on Edit. Then, I'll hit my F key to frame the object. I'll click on Line Fill so we can see the topology. Then, I'll go to Geometry and Crease. For my crease tolerance, I'll set that to 40. That's just putting in the edges that I want creased. You may need to adjust that depending on your object. Now, I'll zoom up on this edge, and when I click the Crease button you can see it added edge loops to these edges. That'll help us keep a sharp edge. So I'll zoom back out. I'll close Geometry and go to Poly Groups. For Group by Normals, I'll change the angle to 52 and hit Enter. Now, I'll click on Groups by Normals. Now, the different colors are the different poly groups, and that will help ZRemesher to find those edges. So I'll go back to Geometry. I'll click on ZRemesher. I want the adaptive size and curve strength set to 100. I want Keep Groups on, and that's for my poly groups. I want Smooth Groups to be set to zero, and now I'll click ZRemesher. As you can see, I don't have enough polygons to define the object the way I want. So under Target Polygons Count, I'm going to change this to five and hit Enter. Then, I'll click on ZRemesher. But first, I'll hit CTRL+Z to go back, and then I'll click on ZRemesher. Now, that's what I wanted. You can adjust your target polygon count to whatever you need for your model. Keep in mind how close you'll need to render your object. Now, all we need to do to go back to Cinema 4D is I can drag this down and click on GoZ, and Continue. That brings our retopologized object back into Cinema 4D. Just to recap the ZRemesher settings, remember to use Crease and set tolerance to 40. You can adjust it if necessary. Make poly groups using Groups by Normals, but adjust max angle if necessary. Set adaptive size and curve strength to 100. Turn on Keep Groups and set Smooth Groups to zero. Then, just click the ZRemesher button. If necessary, adjust the target polygons count to get the mesh density that you want. Now, we'll take a look at UV Master in ZBrush. So I'll click on the object. Go to Script, User Scripts, and GoZBrushFromCinema4D, and ZBrush will open. Now, I'll click on Hide to close the browser, and I'll drag in the viewport to place the object. Then, I'll click on Edit. I'll click the F key to frame it in the viewport. Then, I'll turn on Line Fill so we can see topology and the poly groups. Then, I'll come up here to Zplugin, and I'll click this pin button. Then, it will pin my pallet over here, and that'll make it easier for us. So I can go down to UV Master, and the first thing I'll want to do is click Work On Clone. That way, I won't mess up my original object, and I can just copy and paste the UVs back to the original object. So I'll click Work On Clone. If I scroll down here, you can see that my object has a CL in front of it, and that means that I'm working on the clone. When I get done, I can copy the UVs, and then click on my original object, and then paste them. So I'll go back up here and click Unwrap. Now that UVs are done, I'll click on Flatten, and my UVs are all set up. This might be exactly what you want, but if not I'm going to show you a couple more options. So I'll click on Unflatten, and I'll click Check Scenes. Then, I'll go to Enable Control Panning, and I'll change my draw size. I'll right-click, and then drag this down. Now, let's say I didn't want this scene going across here. So I'll protect that area. I'll click the Protect button, and I'll paint in this area. First, I'll turn off Line Fill. Then, I'll click the Attract button, and I'll paint this area down here with blue for attract. Then, I'll click Unwrap. Now, you can see that the seam is down here where I painted the attract color, and it's not up here anymore where I painted the protect. Keep in mind that this is just for quick UVs and it isn't really precise. So if you need your UVs to be very precise, you should do them in Cinema 4D or another UV layout program. Now, I'll show you one more option. I can turn on Poly Groups, and then click Unwrap. Now if I click Flatten, you can see the UVs are all separated by the poly group. So I'll click Unflatten, and I'll click Copy UVs. Then, I'll come down here and click on my original object. Then, I'll come back to the UV Master and click Paste UVs. Now, the UVs are set up on the original object. So all I need to do is click on GoZ and go back to Cinema 4D. Now, I have my object back in Cinema 4D with the UVs laid out. That was a quick overview of ZRemesher and UV Master.
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