MobilityDL: A Review of Deep Learning From Trajectory Data

Trajectory data combines the complexities of time series, spatial data, and (sometimes irrational) movement behavior. As data availability and computing power have increased, so has the popularity of deep learning from trajectory data. This review paper provides the first comprehensive overview of deep learning approaches for trajectory data. We have identified eight specific mobility use cases which we analyze with regards to the deep learning models and the training data used. Besides a comprehensive quantitative review of the literature since 2018, the main contribution of our work is the data-centric analysis of recent work in this field, placing it along the mobility data continuum which ranges from detailed dense trajectories of individual movers (quasi-continuous tracking data), to sparse trajectories (such as check-in data), and aggregated trajectories (crowd information).

MCLFIQ: Mobile Contactless Fingerprint Image Quality

We propose MCLFIQ: Mobile Contactless Fingerprint Image Quality, the first quality assessment algorithm for mobile contactless fingerprint samples. To this end, we retrained the NIST Fingerprint Image Quality (NFIQ) 2 method, which was originally designed for contact-based fingerprints, with a synthetic contactless fingerprint database. We evaluate the predictive performance of the resulting MCLFIQ model in terms of Error-vs.-Discard Characteristic (EDC) curves on three real-world contactless fingerprint databases using two recognition algorithms. In experiments, the MCLFIQ method is compared against the original NFIQ 2 method and a sharpness-based quality assessment algorithm developed for contactless fingerprint images. Obtained results show that the re-training of NFIQ 2 on synthetic data is a viable alternative to training on real databases. Moreover, the evaluation shows that our MCLFIQ method works more accurate and robust compared to NFIQ 2 and the sharpness-based quality assessment. We suggest considering the proposed MCLFIQ method as a candidate for a new standard algorithm for contactless fingerprint quality assessment.