ArcFace
A margin-based face-recognition objective that learns angularly separated identity embeddings on a normalized hypersphere.
Angular-Margin Objective
ArcFace normalizes feature and class-weight vectors and introduces an additive angular margin for the target identity. The objective is to make same-identity embeddings compact while increasing angular separation between identities.
The training loss is not the same thing as the runtime similarity rule. A deployed system normally produces a face embedding and compares it with cosine similarity or another calibrated score.
Deployment Boundary
Detection and alignment errors propagate into the embedding. Thresholds are also domain dependent: camera, pose, illumination, age variation and the required false-match rate matter.
My implementation-oriented comparison of export/runtime behavior is in ONNX and CTranslate2 for ArcFace Models.
Related Computer-Vision Concepts
Direct source: The primary paper or official specification for ArcFace is linked here for verification.