As promised in my last post, I’m bringing to you one small tutorial on how to model rocks in zbrush.
There are many rock modeling techniques online, so this will be just one more to add in the bunch. I hope you’ll find something useful that you can use in your projects. I’m not going to explain zbrush in depth, but you should be able to follow this tutorial without any problem as the tools I’m about to show you are fairly simple.
So lets start . Here’s a few images so you can see what is our goal.
Lets start by adding a sphere on the canvas (the size is not important). After creating the sphere, press T to enter edit mode, and convert the sphere to polymesh3d so you can access dynamesh options.
Next thing you want to do is to convert object into dynamesh, which is one of the best options in zbrush, and you will soon see why. Dynamesh options can be found in the tools menu, under geometry.
Lets dig In a little bit and see what is so special about the dynamesh. Enable dynamesh and take a look what will happen to the mesh topology. To some people, it might look a bit messy since the polygons are not 100% quads, but you don’t need to worry about that, trust me ;)
Lets try to edit an object a little bit with the move brush. As you can see there is a lot of polygon stretching, and this is where dynamesh comes to our aid.
Let’s redynamesh the object and see what will happen. While holding CTRL, press left mouse button and drag it on an empty space on canvas, and let go of the mouse button. Zbrush will redynamesh the object, and the speed of that process will depend on the dynamesh resolution ( more res = more computation time ). You will see that the topology has changed. Area where polygons were stretched is recalculated, and the polygon density is uniform again. You can see the result on the image bellow.
That is the power of dynamesh. You stretch the mesh, compress it, cut it….. do what ever you want, and just redynamesh it when you mess the topology too much. This is the basic workflow that is used for rocks creation in zbrush, and it can be applied to literally anything.
Now that you are familiar with the dynamesh, we can dig in into modeling. First we need to load one special brush, since it is not in the brush menu by default. Press (,) to load the lightbox menu, click on BRUSH, find TRIM folder, and load TrimSmoothBorder brush. by double clicking on it.
This brush is quite harsh, so you might want to dial down the Z-intensity, which is located just above the canvas, or you can access it by pressing and holding the spacebar.
Let’s mess around with our sphere. If you never worked in zbrush, don’t worry if you don’t succeed the first time. It will take some time to get familiar with the brush.
Large >>> Medium >>> Small
First thing we want to do is to define large shapes, so don’t bother zooming in too much. There will be plenty time for that. Relax, and try to mess around with the model, while getting familiar with the trim brush.
Bare in mind that if you want to make a rock that looks realistic, do not model them from the memory, use reference images. App I’m using for sorting reference images is called Pureref and it is available for both macOS and Windows. Here is the link
On images bellow, you can see the result of using TrimSmoothBorder brush on our sphere.
The next step will be to add medium scale details. For this, we will have to crank up the number of polygons, so lets access the dynamesh menu again, and lets put 256 for density ( you can enter random number, it doesn’t have to be 256, 512…etc ) ,redynamesh it ( hold ctrl, left mouse press drag and release on an empty portion of the canvas ). This time you want to reduce the brush size, and again, do not zoom too much, you don’t want to go into small details right now.
Once we are done with large and medium scale details, we are ready for the final phase, which is adding the small scale (high frequency) details, and this is not something we are going to do manually since it could take hours/days. Instead of modeling details manually, we are going to use brush alphas.
It is time to crank up the density one more time. You can put some crazy high value if you want to add ridiculously small details but for this tutorial, lets stick with the value of around 500.
This time we will go back to standard brush, and change the stroke from freehand to dragrect, and load alphas you want to use by opening alphas menu, and clicking on import.
I’m using awesome JRO rock alphas that can be found here, and the package is called “Zbrush stylized rock brushes”. It is cheap, but you have one free package as well that you can use for practice.
Next step is pretty simple. Chose one alpha, click on the object and adjust the size of the alpha by dragging the mouse and releasing it once you are satisfied with the size. How much alpha is visible on the object you can adjust with z intensity. It is easy to over do it, so try not to add too much. Try few times with different z intensity values, before you start adding your shapes.
In case you find yourself in situation in which you broke large and medium shapes you have already created, you can always go back to trim brush and redo them, repeating the process from large to small once again.
And here it is, the final result that took me few minutes to finish. With a bit more time, the result can be much better, but for this mini tutorials, it’s fine.
In second part of the tutorial, I’ll show you how to prepare custom shaped objects in 3dsmax, and then adding details in zbrush. Until then, you can check this short video showing the whole process from start to finish.
I know that written tutorials are not as easy to follow as videos are, but I hope I’ve managed to show you something useful. If something is not clear enough, feel free to leave me a comment.
Until next time, Dynasmash it!!!