A Review on Coarse to Fine-Grained Animal Action Recognition

TL;DR

This review surveys current methods and challenges in coarse and fine-grained animal action recognition, emphasizing the need for specialized techniques and datasets to handle the complexity of animal behaviors in natural environments.

Contribution

It provides a comprehensive overview of existing approaches, highlights unique challenges, and introduces a new dataset to advance fine-grained animal action recognition research.

Findings

Spatio-temporal deep learning frameworks show promise in animal behavior analysis.

Current datasets are limited and need expansion for better model training.

Recognizing subtle animal actions remains a significant challenge due to environmental complexity.

Abstract

This review provides an in-depth exploration of the field of animal action recognition, focusing on coarse-grained (CG) and fine-grained (FG) techniques. The primary aim is to examine the current state of research in animal behaviour recognition and to elucidate the unique challenges associated with recognising subtle animal actions in outdoor environments. These challenges differ significantly from those encountered in human action recognition due to factors such as non-rigid body structures, frequent occlusions, and the lack of large-scale, annotated datasets. The review begins by discussing the evolution of human action recognition, a more established field, highlighting how it progressed from broad, coarse actions in controlled settings to the demand for fine-grained recognition in dynamic environments. This shift is particularly relevant for animal action recognition, where behavioural variability and environmental complexity present unique challenges that human-centric models cannot fully address. The review then underscores the critical differences between human and animal action recognition, with an emphasis on high intra-species variability, unstructured datasets, and the natural complexity of animal habitats. Techniques like spatio-temporal deep learning frameworks (e.g., SlowFast) are evaluated for their effectiveness in animal behaviour analysis, along with the limitations of existing datasets. By assessing the strengths and weaknesses of current methodologies and introducing a recently-published dataset, the review outlines future directions for advancing fine-grained action recognition, aiming to improve accuracy and generalisability in behaviour analysis across species.