Join Ryan Kittleson for an in-depth discussion in this video Working with dynamic brush scale, part of ZBrush: Tips & Tricks.
- Setting the size of your brush really should be the simplest thing of all but in ZBrush there are a lot of complications that make it frustrating to manage. In this video, I'll show you all the settings and circumstances that effect brush size, as well as getting it under control. With the more recent versions of ZBrush, ZBrush has included something called dynamic brush scale, which is on by default and it's right up here with the draw size and to turn it on and off, you might think that you just click on dynamic, but you actually have to hold down shift and then click on it and then you can turn dynamic on and off by holding down shift and clicking.
So, first let's talk about the traditional brush sizing before dynamic came out. So, make sure that dynamic is a darker gray, so that it's off. And this way draw size is based on the size of the brush on the screen. So, what ever this number is, is the radius of the brush in pixels. So, if you set it to something close to 500, then it means that it's about a thousand pixels from one side to the other. And that's easy to understand, it's just the size of the brush on the screen.
However, where this started to become a problem is that you might be working on a part of your model and the brush size is really good for working on details at this size but if you zoom out a little bit, the size of the brush stays the same relative to the screen but it's bigger relative to the model. Or conversely, if you zoom in really close, now the brush is really small compared to the model. Even though it's the same size relative to the screen. So, just to demonstrate, I'm going to to sculpt something here and then zoom out somewhat and then sculpt again and you can see that that sculpting is really different in size.
If I zoom out even more, you can see now it's just completely taken over the model. So I'm going to hit control z a few times to undo that. Now, let's see the new feature called dynamic brush size. I'm going to hold down shift and click on dynamic to turn that on. So, now the way this works, no matter how close you zoom in, the brush always stays the same size relative to the model. So, if we sculpt something here, and then zoom out, sculpt again, so on and so forth. The brush is shrinking relative to the screen if we zoom out but it's staying the same size relative to the model.
And that's nice because it can help you stay consistent. Let's say if you're making strokes that are something that you want to be a particular size and if you zoom out you don't want that size of that stroke to change. So, dynamic is helpful in that sense. So, I'll just hit control z to undo those. Now, this sounds great, it sounds like the solution to all your problems, right? Well, there are some problems that get in to because of this dynamic brush setting. For one, dynamic brush size really doesn't like it if your model is significantly larger or smaller than two units in its longest dimension.
So, let's see how big this model really is. I'm going to go in to geometry and let's go to size and you can see that the size of the objects is 1.6. So that's pretty close to two and that's the size that ZBrush really likes for models to be. So, let's see what happens if we bring this really far down, something like .01 roughly. Okay, now let's zoom in on this. I'm going to hit f to frame in on it. So, you can see now because the model's really small a draw size of 55 is actually really huge.
And if I come down low, you can see that a draw size of one is kind of small but there's a lot of instances where I might want a brush that's even smaller than that. Say there's a lot of difference between one and two and if you want a brush size that's in between that, seems like you might be kind of out of luck. Alternatively, let's see what happens if the size is really big, like 100. I'm going to hit f again to frame and zoom out. Now you can see, we can get a brush here, that if we bring the draw size all the way up to a thousand, all the way up to the maximum, it's still pretty small and you can't really get any bigger and then if you go anywhere below 100 it's just insignificantly small.
The dynamic brush has trouble getting very large on very large models or very small on small models. So, the solution for this is to go to preferences, draw. And we want to change the dynamic brush scale. It's a slider that basically acts as a multiplier for the dynamic brush size. I find that setting this number to be about the same as the size of the model, gets good results. So, we scaled the model up to 100. Now, the maximum of this goes up to 10.
So, let's see what happens. Okay, now you can see that if we bring it up to a thousand, it's quite a bit bigger than it was before but it's still not quite big enough for some things that you might want to do. So, let's go back to preferences and we can change the max brush size and let's raise this up to 5,000. Now, we can get a brush that's pretty big. Big enough for pretty much anything you want to do. And now you get a nice range of sizes here with the slider.
So, let's see what happens when we go back down to the really small model, something like .1, roughly. And hit f to zoom in. So, now that draw size, since we have that multiplier on it. Now the lowest size you can get is really big. So, we have to go back to preferences, change the dynamic brush size to something like, that matches the model like .1 and there you get a result that feels a bit more reasonable. So, if you want to work with dynamic brush size, you have to keep in mind all of these different scale issues.
As you can see, what was meant to be a feature to make things simpler has actually made things more cumbersome. But now that you know these tips, it should be at least manageable to work with brush size.
Skill Level Intermediate
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