Social media play an important role in the daily life of people around the globe and users have emerged as an active part of news distribution as well as production. The threatening pandemic of COVID-19 has been the lead subject in online discussions and posts, resulting to large amounts of related social media data, which can be utilised to reinforce the crisis management in several ways. Towards this direction, we propose a novel framework to collect, analyse, and visualise Twitter posts, which has been tailored to specifically monitor the virus spread in severely affected Italy. We present and evaluate a deep learning localisation technique that geotags posts based on the locations mentioned in their text, a face detection algorithm to estimate the number of people appearing in posted images, and a community detection approach to identify communities of Twitter users. Moreover, we propose further analysis of the collected posts to predict their reliability and to detect trending topics and events. Finally, we demonstrate an online platform that comprises an interactive map to display and filter analysed posts, utilising the outcome of the localisation technique, and a visual analytics dashboard that visualises the results of the topic, community, and event detection methodologies.

Recognition of daily actions is an essential part of Ambient Assisted Living (AAL) applications and still not fully solved. In this work, we propose a novel framework for the recognition of actions of daily living from depth-videos. The framework is based on low-level human pose movement descriptors extracted from 3D joint trajectories as well as differential values that encode speed and acceleration information. The joints are detected using a depth sensor. The low-level descriptors are then aggregated into discriminative high-level action representations by modeling prototype pose movements with Gaussian Mixtures and then using a Fisher encoding schema. The resulting Fisher vectors are suitable to train Linear SVM classifiers so as to recognize actions in pre-segmented video clips, alleviating the need for additional parameter search with non-linear kernels or neural network tuning. Experimental evaluation on two well-known RGB-D action datasets reveal that the proposed framework achieves close to state-of-the-art performance whilst maintaining high processing speeds.

A novel work for Ambient Assisted Living applications is presented here. More specifically, this paper focuses on activity recognition from recordings of daily living captured by wearable cameras. It constructs a discriminant object centric motion descriptor for representing the micro-actions within the viewpoint of the action maker so as to later define the activity that he/she performs. The accumulation of these activities build patterns over time that can be used to study the behavior of the end-users, which is very useful for health application and monitoring of patients inside their own dwellings or their behavior inside a controlled environment.