Cristina Bustos

In the face of mounting pressures—including climate change—public authorities and researchers are actively exploring strategies to advance sustainable and active transportation modes. One critical challenge is the transition from car-dominated mobility to walkable urban environments, which promises to reduce congestion, lower pollution, and enhance public health. However, effective planning for this transition is hampered by the lack of reliable, city-wide data on pedestrian infrastructure—a data gap that impedes efforts to improve walkability and accessibility. To address this shortfall, we introduce a novel, deep learning-based scalable pipeline for extracting continuous, geocoded sidewalk networks from high-resolution aerial imagery. Our approach integrates advanced semantic segmentation with geometric and graph-based post-processing to convert raw imagery into structured and interconnected pedestrian networks. This work provides urban planners and policymakers with the robust data needed for informed decision-making and paves the way for more sustainable, human-centred urban mobility strategies.

This paper studies the contribution of the visual road scene to estimate the driver-reported stress levels. Our research leverages on previous work showing that environmental factors, such as traffic congestion, weather conditions, and driving context, impact driver's stress. Each of the models we evaluated is trained and tested with the publicly available AffectiveROAD dataset to estimate three categories of driver-reported stress level. We test three types of modelling approaches: (i) single-frame baselines (Random Forest, SVM, and Convolutional Neural Networks); (ii) Temporal Segment Networks (TSN) and two variants of it, which use learned weights (TSN-w) and LSTM (TSN-LSTM) as consensus functions; and (iii) video classification Transformers. Our experiments reveal that the TSN-w, TSN-LSTM, and Transformer models achieve statistically equivalent performances, all significantly outperforming the other models. Particularly noteworthy is TSN-w, which attains the highest performance observed with an average accuracy of 0.77. We further provide an explainability analysis using Class Activation Mapping and image semantic segmentation to identify the elements of the road scene that contribute the most to high levels of stress. Our results demonstrate that the visible road scene offers significant contextual information for estimating driver-reported stress levels, with potential implications for the design of safer urban road environments.

Following European directives, asbestos–cement corrugated roofing tiles must be eliminated by 2025. Therefore, identifying asbestos–cement rooftops is the first necessary step to proceed with their removal. Unfortunately, asbestos detection is a challenging task. Current procedures for identifying asbestos require human exploration, which is costly and slow. This has motivated the interest of governments and companies in developing automatic tools that can help to detect and classify these types of materials that are dangerous to the population. This paper explores multiple computer vision techniques based on Deep Learning to advance the automatic detection of asbestos in aerial images. On the one hand, we trained and tested two classification architectures, obtaining high accuracy levels. On the other, we implemented an explainable AI method to discern what information in an RGB image is relevant for a successful classification, ensuring that our classifiers’ learning process is guided by the right variables—color, surface patterns, texture, etc.—observable on asbestos rooftops.

The possibility of recognizing diverse aspects of human behavior and environmental context from passively captured data motivates its use for mental health assessment. In this paper, we analyze the contribution of different passively collected sensor data types (WiFi, GPS, Social interaction, Phone Log, Physical Activity, Audio, and Academic features) to predict daily selfreport stress and PHQ-9 depression score. First, we compute 125 mid-level features from the original raw data. These 125 features include groups of features from the different sensor data types. Then, we evaluate the contribution of each feature type by comparing the performance of Neural Network models trained with all features against Neural Network models trained with specific feature groups. Our results show that WiFi features (which encode mobility patterns) and Phone Log features (which encode information correlated with sleep patterns), provide significative information for stress and depression prediction.

This work presents a study on how to exploit the CLIP embedding space to perform Visual Sentiment Analysis. We experiment with two architectures built on top of the CLIP embedding space, which we denote by CLIP-E. We train the CLIP-E models with WEBEmo, the largest publicly available and manually labeled benchmark for Visual Sentiment Analysis, and perform two sets of experiments. First, we test on WEBEmo and compare the CLIP-E architectures with state-of-the-art (SOTA) models and with CLIP Zero-Shot. Second, we perform cross dataset evaluation, and test the CLIP-E architectures trained with WEBEmo on other Visual Sentiment Analysis benchmarks. Our results show that the CLIP-E approaches outperform SOTA models in WEBEmo fine grained categorization, and they also generalize better when tested on datasets that have not been seen during training. Interestingly, we observed that for the FI dataset, CLIP Zero-Shot produces better accuracies than SOTA models and CLIP-E trained on WEBEmo. These results motivate several questions that we discuss in this paper, such as how we should design new benchmarks and evaluate Visual Sentiment Analysis, and whether we should keep designing tailored Deep Learning models for Visual Sentiment Analysis or focus our efforts on better using the knowledge encoded in large vision-language models such as CLIP for this task.

The possibility of recognizing diverse aspects of human behavior and environmental context from passively captured data motivates its use for mental health assessment. In this paper, we analyze the contribution of different passively collected sensor data types (WiFi, GPS, Social interaction, Phone Log, Physical Activity, Audio, and Academic features) to predict daily self-report stress and PHQ-9 depression score. First, we compute 125 mid-level features from the original raw data. These 125 features include groups of features from the different sensor data types. Then, we evaluate the contribution of each feature type by comparing the performance of Neural Network models trained with all features against Neural Network models trained with specific feature groups. Our results show that WiFi features (which encode mobility patterns) and Phone Log features (which encode information correlated with sleep patterns), provide significative information for stress and depression prediction.

At the moment, urban mobility research and governmental initiatives are mostly focused on motor-related issues, e.g. the problems of congestion and pollution. And yet, we can not disregard the most vulnerable elements in the urban landscape: pedestrians, exposed to higher risks than other road users. Indeed, safe, accessible, and sustainable transport systems in cities are a core target of the UN's 2030 Agenda. Thus, there is an opportunity to apply advanced computational tools to the problem of traffic safety, in regards especially to pedestrians, who have been often overlooked in the past. This paper combines public data sources, large-scale street imagery and computer vision techniques to approach pedestrian and vehicle safety with an automated, relatively simple, and universally-applicable data-processing scheme. The steps involved in this pipeline include the adaptation and training of a Residual Convolutional Neural Network to determine a hazard index for each given urban scene, as well as an interpretability analysis based on image segmentation and class activation mapping on those same images. Combined, the outcome of this computational approach is a fine-grained map of hazard levels across a city, and an heuristic to identify interventions that might simultaneously improve pedestrian and vehicle safety. The proposed framework should be taken as a complement to the work of urban planners and public authorities.