SHARDeg: A Benchmark for Skeletal Human Action Recognition in Degraded Scenarios

TL;DR

This paper introduces SHARDeg, a benchmark for evaluating skeletal human action recognition models under real-world degraded video conditions, revealing significant impacts of degradation types and proposing mitigation strategies.

Contribution

It provides the first comprehensive degradation benchmark for SHAR on NTU-RGB+D-120 and assesses the robustness of leading models under various real-world degradations.

Findings

Degradation type significantly affects model accuracy (>40% variation).

Interpolation improves model performance by up to >40%.

Rough Path Theory-based LogSigRNN outperforms DeGCN at low frame rates.

Abstract

Computer vision (CV) models for detection, prediction or classification tasks operate on video data-streams that are often degraded in the real world, due to deployment in real-time or on resource-constrained hardware. It is therefore critical that these models are robust to degraded data, but state of the art (SoTA) models are often insufficiently assessed with these real-world constraints in mind. This is exemplified by Skeletal Human Action Recognition (SHAR), which is critical in many CV pipelines operating in real-time and at the edge, but robustness to degraded data has previously only been shallowly and inconsistently assessed. Here we address this issue for SHAR by providing an important first data degradation benchmark on the most detailed and largest 3D open dataset, NTU-RGB+D-120, and assess the robustness of five leading SHAR models to three forms of degradation that represent real-world issues. We demonstrate the need for this benchmark by showing that the form of degradation, which has not previously been considered, has a large impact on model accuracy; at the same effective frame rate, model accuracy can vary by >40% depending on degradation type. We also identify that temporal regularity of frames in degraded SHAR data is likely a major driver of differences in model performance, and harness this to improve performance of existing models by up to >40%, through employing a simple mitigation approach based on interpolation. Finally, we highlight how our benchmark has helped identify an important degradation-resistant SHAR model based in Rough Path Theory; the LogSigRNN SHAR model outperforms the SoTA DeGCN model in five out of six cases at low frame rates by an average accuracy of 6%, despite trailing the SoTA model by 11-12% on un-degraded data at high frame rates (30 FPS).