When in the need for fine geometric surface detail, users face a choice of using bump (or normal) maps versus displacement maps. Traditionally, users coming from other rendering engines, heavily rely on bump (either scalar bump maps or normal maps): this is mainly due to the fact that other rendering engines are not efficient at rendering true displacements.
3Delight is very fast at rendering displacements, this is due to its proprietary displacement technology.
Furthermore 3Delight for Maya allows users to use the Maya Displacement node also to perfrom bump, so to be able to easily, and with predictive result, swich from displacement to bump when necessary.
Maya bump node allows users to use "normal maps" for bump effects, this however should not be used for offline high quality rendering results. Normal maps are ok for game-like and hardware rendering but make no sense for film, vfx and animation work. You should avoid using normal maps for such line of works and rely instead on scalar (greyscale) bump map for lower quality results and on scalar/vector displacement for higher quality results.
3Delight for Maya offers extension attributes on Maya's displacement node, allowing users to use this node for both displacement and bump with a single switch. This article helps you being informed about pros and cons of each.
We strongly recommend to use the Maya Displacement node, even for bump effects (instead of the bump node) for the following reasons:
- easy to switch between bump and displacement if user chooses to do so due to the "compatibility" of greyscale scalar maps for both effects
- easy to predict how much to bump and displace in real world unit scale, which is easy to compare to the actual object scale
Displacement maps (scalar/vector) and bump maps (scalar/normal) are "non-color" data, therefore it should not be interpreted as "linear" data. We also recommend not to use PhotoShop for creating bump/displacement texture maps, use instead procedural textures and proper texture authoring tools able to output linear data in 16 bit EXR or TIF formats, a 2D tool like Krita or 3D paint applications like Substance, Mudbox, ZBrush or Mari.
Pros of Displacement
Using displacement has major advantages over bump:
- displacement in 3delight is faster than in other renderers and is actually usable and recommended for high quality productions
- higher quality, real, geometric details on your surfaces
- being a geometric feature, displacement casts accurate ray-traced shadows
- better and more accurate outline detections, especially at the silhouette of objects
- highlights are better "caught" by the geometric details of displacement
- due to the real geometric nature of displacement, it is easy to understand how much to displace inward and outward in physical unit scale
- subsurface effects will take into account of the displacement and produce more realistic results
Cons of Displacement
- Slower than bump but much better visual quality (and not as slow as other rendering engines)
- More memory is necessary compared to Bump.
Pros of Bump
- Faster than displacement, but much lower quality results.
- No extra memory necessary
Guidelines for Artists
- Never use normal maps for high quality production such as VFX, film and animation work.
- Use (scalar) displacement maps for anything that is "hero" and on-screen / near camera
- Use vector displacement when needing very large displacements that grow in directions that mutate while being displaced
- Do not use displacement on super highly tessellated polygon meshes, as it makes no sense: instead use reasonable tessellated meshes, with subdivision surfaces and displacement map for finer details
- Use scalar (greyscale) bump maps for anything that is not visually important and far from the camera
- Always treat displacement and bump as "non-color" data that is actually "linear".
- Author your displacement and bump using procedural textures or ad-hoc tools for texture paininting in linear space, such as Krita, or 3D paint apps such as Substance, Mudbox, ZBrush, Mari. Avoid PhotoShop.