9 research outputs found
TranSG: Transformer-Based Skeleton Graph Prototype Contrastive Learning with Structure-Trajectory Prompted Reconstruction for Person Re-Identification
Person re-identification (re-ID) via 3D skeleton data is an emerging topic
with prominent advantages. Existing methods usually design skeleton descriptors
with raw body joints or perform skeleton sequence representation learning.
However, they typically cannot concurrently model different body-component
relations, and rarely explore useful semantics from fine-grained
representations of body joints. In this paper, we propose a generic
Transformer-based Skeleton Graph prototype contrastive learning (TranSG)
approach with structure-trajectory prompted reconstruction to fully capture
skeletal relations and valuable spatial-temporal semantics from skeleton graphs
for person re-ID. Specifically, we first devise the Skeleton Graph Transformer
(SGT) to simultaneously learn body and motion relations within skeleton graphs,
so as to aggregate key correlative node features into graph representations.
Then, we propose the Graph Prototype Contrastive learning (GPC) to mine the
most typical graph features (graph prototypes) of each identity, and contrast
the inherent similarity between graph representations and different prototypes
from both skeleton and sequence levels to learn discriminative graph
representations. Last, a graph Structure-Trajectory Prompted Reconstruction
(STPR) mechanism is proposed to exploit the spatial and temporal contexts of
graph nodes to prompt skeleton graph reconstruction, which facilitates
capturing more valuable patterns and graph semantics for person re-ID.
Empirical evaluations demonstrate that TranSG significantly outperforms
existing state-of-the-art methods. We further show its generality under
different graph modeling, RGB-estimated skeletons, and unsupervised scenarios.Comment: Accepted by CVPR 2023. Codes are available at
https://github.com/Kali-Hac/TranSG. Supplemental material is included in the
conference proceeding
Can ChatGPT Assess Human Personalities? A General Evaluation Framework
Large Language Models (LLMs) especially ChatGPT have produced impressive
results in various areas, but their potential human-like psychology is still
largely unexplored. Existing works study the virtual personalities of LLMs but
rarely explore the possibility of analyzing human personalities via LLMs. This
paper presents a generic evaluation framework for LLMs to assess human
personalities based on Myers Briggs Type Indicator (MBTI) tests. Specifically,
we first devise unbiased prompts by randomly permuting options in MBTI
questions and adopt the average testing result to encourage more impartial
answer generation. Then, we propose to replace the subject in question
statements to enable flexible queries and assessments on different subjects
from LLMs. Finally, we re-formulate the question instructions in a manner of
correctness evaluation to facilitate LLMs to generate clearer responses. The
proposed framework enables LLMs to flexibly assess personalities of different
groups of people. We further propose three evaluation metrics to measure the
consistency, robustness, and fairness of assessment results from
state-of-the-art LLMs including ChatGPT and GPT-4. Our experiments reveal
ChatGPT's ability to assess human personalities, and the average results
demonstrate that it can achieve more consistent and fairer assessments in spite
of lower robustness against prompt biases compared with InstructGPT.Comment: Accepted to EMNLP 2023. Our codes are available at
https://github.com/Kali-Hac/ChatGPT-MBT
Self-Supervised Gait Encoding with Locality-Aware Attention for Person Re-Identification
Gait-based person re-identification (Re-ID) is valuable for safety-critical
applications, and using only 3D skeleton data to extract discriminative gait
features for person Re-ID is an emerging open topic. Existing methods either
adopt hand-crafted features or learn gait features by traditional supervised
learning paradigms. Unlike previous methods, we for the first time propose a
generic gait encoding approach that can utilize unlabeled skeleton data to
learn gait representations in a self-supervised manner. Specifically, we first
propose to introduce self-supervision by learning to reconstruct input skeleton
sequences in reverse order, which facilitates learning richer high-level
semantics and better gait representations. Second, inspired by the fact that
motion's continuity endows temporally adjacent skeletons with higher
correlations ("locality"), we propose a locality-aware attention mechanism that
encourages learning larger attention weights for temporally adjacent skeletons
when reconstructing current skeleton, so as to learn locality when encoding
gait. Finally, we propose Attention-based Gait Encodings (AGEs), which are
built using context vectors learned by locality-aware attention, as final gait
representations. AGEs are directly utilized to realize effective person Re-ID.
Our approach typically improves existing skeleton-based methods by 10-20%
Rank-1 accuracy, and it achieves comparable or even superior performance to
multi-modal methods with extra RGB or depth information. Our codes are
available at https://github.com/Kali-Hac/SGE-LA.Comment: Accepted at IJCAI 2020 Main Track. Sole copyright holder is IJCAI.
Codes are available at https://github.com/Kali-Hac/SGE-L
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
Hierarchical skeleton Meta-Prototype Contrastive learning with hard skeleton mining for unsupervised person re-identification
With rapid advancements in depth sensors and deep learning, skeleton-based person re-identification (re-ID) models have recently achieved remarkable progress with many advantages. Most existing solutions learn single-level skeleton features from body joints with the assumption of equal skeleton importance, while they typically lack the ability to exploit more informative skeleton features from various levels such as limb level with more global body patterns. The label dependency of these methods also limits their flexibility in learning more general skeleton representations. This paper proposes a generic unsupervised Hierarchical skeleton Meta-Prototype Contrastive learning (Hi-MPC) approach with Hard Skeleton Mining (HSM) for person re-ID with unlabeled 3D skeletons. Firstly, we construct hierarchical representations of skeletons to model coarse-to-fine body and motion features from the levels of body joints, components, and limbs. Then a hierarchical meta-prototype contrastive learning model is proposed to cluster and contrast the most typical skeleton features (“prototypes”) from different-level skeletons. By converting original prototypes into meta-prototypes with multiple homogeneous transformations, we induce the model to learn the inherent consistency of prototypes to capture more effective skeleton features for person re-ID. Furthermore, we devise a hard skeleton mining mechanism to adaptively infer the informative importance of each skeleton, so as to focus on harder skeletons to learn more discriminative skeleton representations. Extensive evaluations on five datasets demonstrate that our approach outperforms a wide variety of state-of-the-art skeleton-based methods. We further show the general applicability of our method to cross-view person re-ID and RGB-based scenarios with estimated skeletons.National Research Foundation (NRF)This research is supported by the National Research Foundation, Singapore under its AI Singapore Programme (AISG Award No: AISG2-PhD/2022-01-034[T])