Smart Blue Light Pole-based Real-Time Crowd Counting for Smart Campuses

Yitao Chen, Kaiqi Zhao, Krishna Sriharsha Gundu, Zohair Zaidi, Ming Zhao

Abstract: Crowd counting on a smart campus can provide valuable insights into pedestrian behaviors and is critical to making decisions about campus designs and improvements. Conventional image or video based crowd-counting approaches have serious privacy risks, while cloud-based solutions also face challenges in providing real-time responses. This paper proposes Height-AWare Human Classifier for Crowd Counting (HAWCCC), a real-time, cost-effective, and privacy-protected smart blue light pole-based crowd-counting framework for smart campuses, using Light Detection and Range (LiDAR) sensors and computing devices installed on the blue light poles to collect traffic data and analyze patterns in real time while protecting data privacy. HAWC-CC is built upon two novel methods. The first is an adaptive clustering approach that dynamically adjusts to point cloud structure and density for accurate and efficient clustering. The second method is a Height-AWare Human Classifier (HAWC) that projects 3D point clouds into height-augmented multiple 2D views and uses a lightweight CNN to detect humans from the projected views. HAWC-CC and its quantized version are then implemented on Nvidia Jetson and Coral TPU for realworld deployment on the blue light poles. A comprehensive 3D LiDAR dataset is collected and curated for single-person detection and crowd counting. An extensive evaluation shows that HAWC-CC significantly outperforms the representative related works (PointNet-CC, AutoEncoder-CC, and OC-SVM-CC) by up to 86.61% in Mean Absolute Error (MAE) and 90.44% in Mean Squared Error (MSE). Additionally, HAWC-CC is the only framework that meets the real-time requirements for LiDAR-based crowd counting, processing one LiDAR sample in 17.42 ms. HAWC demonstrates the highest robustness to limited training data, achieving a notable accuracy of 90.29% with only 0.1% of the training data. HAWC-CC outperforms SOTA RGB image-based solutions in high-density settings, achieving 97.64% accuracy.