Anthropomorphic Features for On-Line Signatures

TL;DR

This paper introduces a novel feature space for on-line signature verification based on anthropomorphic joint movements modeled by a virtual skeletal arm, achieving state-of-the-art results across various benchmarks.

Contribution

It proposes a new anthropomorphic feature space derived from a virtual skeletal arm model to improve on-line signature verification accuracy.

Findings

Achieved state-of-the-art verification performance.

Validated robustness across multiple databases and devices.

Demonstrated effectiveness of anthropomorphic features.

Abstract

Many features have been proposed in on-line signature verification. Generally, these features rely on the position of the on-line signature samples and their dynamic properties, as recorded by a tablet. This paper proposes a novel feature space to describe efficiently on-line signatures. Since producing a signature requires a skeletal arm system and its associated muscles, the new feature space is based on characterizing the movement of the shoulder, the elbow and the wrist joints when signing. As this motion is not directly obtained from a digital tablet, the new features are calculated by means of a virtual skeletal arm (VSA) model, which simulates the architecture of a real arm and forearm. Specifically, the VSA motion is described by its 3D joint position and its joint angles. These anthropomorphic features are worked out from both pen position and orientation through the VSA forward and direct kinematic model. The anthropomorphic features' robustness is proved by achieving state-of-the-art performance with several verifiers and multiple benchmarks on third party signature databases, which were collected with different devices and in different languages and scripts.