Digital sculpting

Digital sculpting means shaping a very dense mesh with brushes, the way you would push, pull, carve and smooth clay, instead of placing vertices and edges one at a time. Blender's manual describes its basic brush as "the standard brush for pushing vertices inwards and outwards from the surface direction" (Blender 3.6 Manual: Toolbar). Because the mesh is dense enough to behave like a surface rather than a cage, you think about form, not topology.

In games, sculpting is mostly a way to make high-poly source detail. The sculpt itself rarely ships. Its shape reaches the game through a lower mesh and a bake, or through a tileable texture.

#Where sculpting fits

Environment artists use sculpting in three main ways:

• Unique organic assets. Rocks, cliffs, roots, statues and terrain pieces. See sculpting rocks and cliffs and modeling rocks, trees and terrain pieces.
• Damage and wear on modeled assets: chipped stone, broken bricks, dented metal. See sculpting damage and wear.
• Tileable surfaces baked into materials: cobbles, brick, cliff faces. See tileable sculpts.

Jared Sobotta's rock work for The Last of Us Part I at Naughty Dog shows all three. He and Anthony Vaccaro modeled, sculpted and textured the Tommy's Dam rocks in Maya, ZBrush and Substance 3D Designer (80 Level: A Closer Look at Rock Assets Made for TLOU…). The high-poly sculpts became "1x1 Macro normals" for the rocks, while two further sculpts, combining hand sculpting and alphas, fed the tiling rock materials (ArtStation: Rock Breakdown).

#Getting enough resolution

A brush can only move vertices that exist. Every sculpting tool therefore has ways to add polygons where you need them. Each has trade-offs, which remeshing covers in more detail.

Subdivision levels are the classic detailing method. In Nomad, when you edit a lower level, the higher-level detail is kept and projected back (Nomad Sculpt manual: Topology). Blender's Multiresolution can even "deform the unsubdivided base mesh instead of the higher levels", so large changes do not create surface noise (Blender Manual: Multiresolution Modifier). ZBrush's subdivisions reach far higher counts than DynaMesh: up to 100 million polygons per SubTool, against about eight million (ZBrush for iPad Help: DynaMesh Sculpting Essentials).

A common sequence is to remesh freely while the shape is changing, then fix the topology and add subdivision levels for the final detail.

#Common sculpting brushes

Every tool ships dozens of brushes, but a handful do most of the work on environment assets. Blender's names and descriptions are a useful neutral vocabulary (Blender 3.6 Manual: Toolbar):

ZBrush equivalents appear in many breakdowns. JaviSkau, a senior environment artist at 31st Union (2K), describes a three-phase rock workflow: blockout and silhouette with DynaMesh and ClayTubes, medium planes and breakage with TrimSmoothBorder, then micro-detail and polish with Polish and hPolish (ArtStation: Rock Sculpting Workflow in ZBrush | 3-Step…). Sergii Zlobin (FRAGLAB) sculpts stone silhouettes with TrimSmoothBorder, Clay BuildUp, Planar and Trim brushes (80 Level: Creating a Stone Wall Material in ZBrush…).

Dannie Carlone, a senior staff environment artist at Santa Monica Studio, published a set of short ZBrush tips with the reminder that "everyone works differently" (ArtStation: Tricks.Tips.Process). Treat brush lists as starting points, not rules.

#Sculpt everything, or model first?

Sculpting is not the only way to make a high poly. Hard-surface assets are usually built with subdivision modeling, booleans or CAD instead (see the high-to-low workflow). Even organic environment work often mixes modeling and sculpting.

#From sculpt to game asset

A finished sculpt can easily run to millions of polygons. To use it in a game you:

1. Reduce it by retopology (manual or automatic) or decimation. Khafizov used ZRemesher for automatic retopology and Decimation Master to prepare meshes for UV mapping (80 Level: How to Make Atmospheric Stylized Modular…).
2. Unwrap the low poly (see UV mapping).
3. Bake normal, ambient occlusion and cavity maps from the sculpt (see baking and normal map).
4. Texture using the baked maps as masks.

Virtualised geometry changes how much of the sculpt can stay as real geometry; see virtualised geometry.

#In different tools

• ZBrush: the dedicated option, with DynaMesh, Sculptris Pro, subdivision levels and ZRemesher (ZBrush for iPad Help: DynaMesh Sculpting Essentials; maxon.net: Base Mesh Creation).
• Blender: Sculpt Mode with Multiresolution, Dyntopo and voxel remesh, free on all platforms (Blender Manual: Multiresolution Modifier; Blender Manual: Dyntopo).
• 3DCoat: voxel and surface sculpting in one program (3DCoat Documentation: Sculpt).
• Nomad Sculpt: multiresolution, voxel remesher and dynamic topology on tablets and desktop (Nomad Sculpt manual: Topology).

Prices, platforms and licences are compared in sculpting software.

#Further reading and watching