ART TIPS: Rock Sculpting

SD-STAFF

Hey everyone,

Here are some tips and resources to help you get you started with sculpting some great looking rocks for your 3D environments.

Create a few simple base meshes
Having a nice simple base mesh that has enough geometry to support detailed sculpting. It helps move things along to get you started to have at least a base mesh that will get you going.

Asymmetrical Design
Avoid uniformity in your rock shape. Asymmetry will make the rock look more natural and also offer more variation when you rotate the rock all around while placing it throughout your environment. That way you have a 360 rock, you place it, rotate it, place it, rotate it, and it always offers a unique look from each different rotation angle

Variation of Details throughout the rock
Focus on varying the surface details such as cracks, crevices, and layered textures. Use different brush sizes and strengths to create a range of details that not only enhances the rock's natural look, but pushes the same idea of the Asymmetrical Design

Material work inside of Unreal Engine
After you have a nice, fairly generic looking texture map applied to your final rock sculpt, you can start to layer details on top of the rock material inside of Unreal. Things like snow, moss, dirt build up, or allowing vertex painting on the surface depending on the rotation of your rocks. There is a quick video for adding moss on geo (this can be replaced with snow / dirt / etc.)

OTHER RESOURCES:

Polycount thread with rock examples:
https://https://polycount.com/discussion/229432/updated-regularly-rock-sculpting

Rocks by environment artist Alen Vejzovic (great reference!)
https://www.artstation.com/vejza

Easily add Moss & Snow in UE5 Beginner Tutorial | DesignwithDan

SD-STAFF

Rock, Cliffside Wall Moss Breakdown using ZBrush

Start off with a flat plane for the rocks and begin sculpting large shapes with the Clay brush. You should be at a decently low poly mesh right now around 20k. This allows you to get the large forms in and the basic details for the rocks with quick iterations of pushing and pulling. While doing this, use the Trim Dynamic brush to polish off areas and get some nice sharp edges for the rocks.

Once you have a pretty good base mesh to work from on the rocks, add more polys and get up into the millions. feel free to use a variety of brushes to get details in, such as:

MalletFast2 Brush: for chipping a lot of the edges off to chip a lot of edges off
Trim Dynamic Brush: for polishing.
Noise Brush: use in spray mode to get some nice rocky crevices and details across the surface
Slash 3 Brush: to use in combination with the MalletFast brush to sculpt some of the cracks

Now you can start adding details such as moss and light patches across the rock.

GrabDoc the rocks and take this into Photoshop to create a mask for where the moss will be placed. In Photoshop, make the moss a black color mask and the white areas a white colored mask. Bring back into ZBrush to do something special with it.

Image of mask created for the moss and patches across the rock. The mask will help you get some nice bevels on the rocks in ZBrush. PS: When importing your mask into ZBrush, flip the image vertically (not rotate, FLIP!) to bring the alpha in upside down and have it show up correctly on the mesh.

Import your alpha/mask back into ZBrush from Photoshop. Mask the ZBrush tool using the alpha. See image below.

Once the ztool is masked using the alpha that was made in Photoshop, bevel that detail into the mesh.
Whatever is grey in the alpha will not move at all. Whatever is black will be pushed back into the mesh and whatever is white will be pushed out towards the camera just like a height map. With the mask, go to the deformation tab in ZBrush and offset the mesh in the Z-Axes. The Z-Axis is facing the camera so it will push and pull things properly.

Offset the mesh until you get the desired amount of bevel from the alpha. With the ztool still masked, use the mask to sculpt in the moss detail without affecting the rock areas. You can use the Noise Brush to go over the moss. Nothing really special here.

This is the resulting ZBrush sculpt after the deformation mask was applied and the noise was sculpted on top of the moss.

From there, it's just normal Photoshop texturing, and you have a nice mask for photoshop to texture in the moss detail.

Hope this helps!