Join Ryan Kittleson for an in-depth discussion in this video Deleting Polygons from a model with subdivision levels, part of ZBrush: Tips & Tricks.
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- As far as the three main types of modeling in Zbrush go, subdivision, editable poly and volumetric, subdivision is the one that is least flexible as far as adding or removing polygons to the main structure of the model. However, it is still possible to do if you know what to look out for. In this video, we'll take a look at a common scenario where we have a body model covered with clothes. The part of the body that's covered with clothes is not visible, and as such, it's adding to the overall polygon count when you subdivide.
This can slow down your computer for no good reason. So let's see how we can remove these polygons without losing detail or subdivision levels for the rest of the model. Okay, I'm going to duplicate this Sub Tool so you can see what I'm talking about. I'm going to go into Sub Tool, and we've got the body selected, so what I want to do is go to Duplicate. So now we've got two copies of it, and what I'm going to do is go to the duplicate, and I want to hide everything but this one.
I'm going to zoom in a little bit here on the face because this is the particular area that has the detail I'm talking about. We can get a good look at the eyes, and what you'll especially see is right here on the eyebrow when I do this. So I'm going to go down in my subdivision levels, so that I can delete some of these polygons. So I'm at the lowest subdivision level, and what I want to do with this model is remove everything below the waist. So I'm going to go into Move Mode, hold down CTRL as I click and drag, and what this is going to do is just mask off along the shape of the object, and actually let's invert that.
So I'm going to hold down CTRL and click in an open area. And let's use that hotkey we did in the last movie. I'm going to hit CTRL X to delete all of that. We can go back into Draw mode, and now if I go back up in the subdivision levels by hitting D, we'll zoom in here on the eye, and it might not look too different, but if we switch between the original and this one, you can see that there's kind of a change in the detail. And actually deleting polygons on a lower subdivision level of a model that has detail on higher subdivision level can often create this sort of corruption of some of the fine detail.
So let's see how we can delete from a model without losing this detail. So I'm going to go ahead and delete this test Sub Tool. Go back up to the main body. And let's go ahead and duplicate again just so we can compare the before and after. So I'll go and select on the duplicate. I'm going to zoom out. And what we can do is just go back in subdivision levels all the way to the bottom with Shift D, and let's do the same thing.
We'll go get our Move tool, click and drag to mask off everything below the waist. Now instead of directly deleting this, what I'm going to do I go back into Draw mode, and let's go Visibility, Hide PT. Okay, now we can go up in our subdivision levels. So I'm going to hit D several times until we get to our highest subdivision level. And then I just need to invert this selection. So I'm going to hit CTRL Shift or hold down CTRL Shift and drag in an open area to invert the visibility.
And now we can go up to Geometry, and we can Delete Lower. Okay now that we've deleted lower subdivision levels, what we can do is go into Geometry, Modify Topology, and then we can go to Del Hidden. Okay, so that just deleted everything that was hidden. Now the issue is that we don't have any subdivision levels in our model anymore, but we can restore those.
So let's go back up to Geometry, and Reconstruct Subdivision Levels. And we'll just have to click this for each subdivision level that we had in the model before. Okay so we're back to the original. Let's go ahead and take a look at this now. Zoom in here, and I'm going to hit D a few times to go back up in our subdivision levels. Okay, so we're back at the highest. And now let's compare that with the original. Okay so you can see going up and down, there's no difference between the two.
So I use this trick all the time if I have a model with detail sculpted in a high subdivision level, and I want to delete part of the model, but I want to make sure that the detail doesn't change at all, I'll make sure to use this trick.