smoothedged

Smoothedged is a term used in computer graphics to describe a technique for smoothing the appearance of polygon edges by adjusting surface normals across adjacent faces. The goal is to reduce facetting and produce more visually continuous shading while preserving sharp edges where desired.

How it works: For each vertex, the normal is commonly computed by averaging the normals of adjacent faces, optionally weighted by face area. Edges are classified by a crease angle: if the angle between the two face normals is below the crease threshold, the edge is smooth and the adjacent faces share a common averaged normal. If the angle exceeds the threshold, the edge remains hard, and the faces retain separate normals to preserve the silhouette. This approach is closely related to smoothing groups or crease attributes used in many 3D packages, but smoothedged frames the process as an edge-aware normal smoothing operation.

Applications and limitations: Smoothedged is applied in character and vehicle modeling, architectural visualization, and any polygonal mesh where smooth shading is beneficial. Benefits include reduced facet visibility and more organic surfaces. Limitations include potential loss of detail on high-contrast surfaces, possible shading artifacts near complex geometry, and a requirement to select an appropriate crease threshold for the model.

Implementation notes: The technique can be implemented in preprocessing steps or in real-time shading. Some pipelines expose per-edge crease data or smoothing groups to control the result. Related concepts include normal mapping, subdivision surfaces, and standard smoothing groups found in Blender, Maya, and 3ds Max.