3D Texturing 3D Texturing Materials & Surface Properties 2 — Questions and Answers
Question 1: What is a 'displacement map' and how does it differ from a normal map?
- Displacement physically moves mesh vertices at render time, while normal maps only fake lighting detail (Correct answer)
- Displacement maps are lower resolution than normal maps
- Normal maps move vertices while displacement maps fake lighting
- Displacement maps only work on metallic surfaces
Correct answer: Displacement physically moves mesh vertices at render time, while normal maps only fake lighting detail
Displacement maps physically alter mesh geometry at render or subdivision time, producing true silhouette detail that normal maps cannot.
Question 2: In PBR, why should the albedo map of a non-metallic surface avoid very dark or very bright values?
- PBR energy conservation breaks with extreme albedo values, producing non-physical reflectance (Correct answer)
- Dark albedos increase render times significantly
- Bright albedos cause UV stretching artifacts
- Very dark albedo maps cause geometry clipping in game engines
Correct answer: PBR energy conservation breaks with extreme albedo values, producing non-physical reflectance
PBR energy conservation requires albedo values to stay within a realistic range (roughly 30–240 sRGB) to avoid surfaces that absorb or emit more light than physically possible.
Question 3: What does an opacity/alpha map control in a 3D material?
- The transparency or cutout regions of a surface, masking which pixels are visible (Correct answer)
- The specular intensity of reflective regions
- The height of displaced geometry
- The color tint of subsurface scattering
Correct answer: The transparency or cutout regions of a surface, masking which pixels are visible
An opacity map defines which pixels of a material are transparent, semi-transparent, or fully opaque, used for foliage, hair cards, and decals.
Question 4: What is 'emissive mapping' used for in a PBR workflow?
- Making specific parts of a surface glow or emit light independent of scene lighting (Correct answer)
- Controlling the roughness of emissive particles
- Baking point light contributions into a texture
- Defining how a surface reflects environment maps
Correct answer: Making specific parts of a surface glow or emit light independent of scene lighting
Emissive maps define areas of a material that appear to emit light, used for screens, neon signs, and glowing circuitry.
Question 5: In PBR texturing, what is the difference between a 'specular workflow' and a 'metallic-roughness workflow'?
- Specular workflow uses separate specular color and glossiness maps; metallic-roughness workflow uses a metallic mask and roughness map (Correct answer)
- Specular workflow only works for metal surfaces
- Metallic-roughness workflow requires three times more texture channels
- Specular workflow is exclusive to Unreal Engine
Correct answer: Specular workflow uses separate specular color and glossiness maps; metallic-roughness workflow uses a metallic mask and roughness map
The specular workflow provides explicit specular color control while the metallic-roughness workflow uses a simpler metallic mask, making it the standard in most game engines.
Question 6: What is 'texel density' in the context of 3D texturing?
- The number of texture pixels per unit of world space, ensuring consistent texture resolution across surfaces (Correct answer)
- The number of UV islands per texture map
- The amount of texture memory used per material
- The ratio of diffuse to specular texture maps
Correct answer: The number of texture pixels per unit of world space, ensuring consistent texture resolution across surfaces
Texel density measures how many texture pixels cover a unit of physical space, and maintaining consistent texel density prevents obvious resolution differences between objects.
3D Texturing 3D Texturing Materials & Surface Properties 2
What is a 'displacement map' and how does it differ from a normal map?