Tracking human motion with multiple cameras using articulated ICP with hard constraints

Questa tesi propone un nuovo algoritmo basato su ICP per il tracking di un modello scheletrico articolato di un corpo umano. L\u2019algoritmo proposto prende in input immagini calibrate di un soggetto, calcola la ricostruzione volumetrica e la linea mediale del corpo e quindi posiziona in modo adeguato il modello, composto di segmenti, in ogni frame usando una versione di ICP modificata (versione che usa una strategia di attraversamento alberi gerarchica che mantiene connessi tutti i segmenti del modello nei giunti relativi). L\u2019approccio proposto usa limiti cinematica per i giunti e un filtro di Kalman esteso per fare il tracking del modello. Il primo contributo originale di questa tesi \ue8 l\u2019algoritmo per trovare i punti sullo scheletro di un volume tridimensionale. L\u2019algoritmo, usando una tecnica di slicing trova l\u2019asse mediale di un volume 3D in modo veloce utilizzando il processore della scheda grafica e le texture units della scheda stessa. Questo algoritmo produce ottimi risultati per quanto riguarda la qualit\ue0 e le prestazioni se comparato con altri algoritmi in letteratura. Un altro contributo originale \ue8 l\u2019introduzione di una nuova strategia di tracking basata su un approccio gerarchico dell\u2019algoritmo ICP, utilizzato per trovare le congruenze tra un modello di corpo umano composto da soli segmenti e un insieme di punti 3D. L\u2019algoritmo usa una versione di ICP dove tutti i punti 3D sono pesati in funzione del segmento del corpo preso in considerazione dall\u2019algoritmo in quel momento. L\u2019applicazione di queste tecniche dimostra la bont\ue0 del metodo e le prestazioni ottenute in termini di qualit\ue0 della stima della posa sono comparabili con altri lavori in letteratura. I risultati presentati nella tesi dimostrano la fattibilit\ue0 dell\u2019approccio generale, che si intende utilizzare in un sistema completo per il tracking di corpi umani senza l\u2019uso di marcatori. In futuro il lavoro pu\uf2 essere esteso ottimizzando l\u2019implementazione e la codifica in modo da poter ottenere prestazioni real-time.This thesis proposed a new ICP-based algorithm for tracking articulated skeletal model of a human body. The proposed algorithm takes as input multiple calibrated views of the subject, computes a volumetric reconstruction and the centerlines of the body and fits the skeletal body model in each frame using a hierarchic tree traversal version of the ICP algorithm that preserves the connection of the segments at the joints. The proposed approach uses the kinematic constraints and an Extended Kalman Filter to track the body pose. The first contribution is a new algorithm to find the skeletal points of a 3D volume. The algorithm using a slicing technique find the medial axis of a volume in a fast way using the graphic card processor and the texture units. This algorithm produce good results in quality and performance compared to other works in literature. Another contribution is the introduction of a new tracking strategy based on a hierarchical application of the ICP standard algorithm to find the match between a stick body model and a set of 3D points. The algorithm use a traversing version of ICP where also all the 3D points are weighted in such a way every limbs of the model can best fit on the right portion of the body. The application of these techniques shown the feasibility of the method and the performances obtained in terms of quality of estimate pose are comparable with other works in literature. The results presented here demonstrate the feasibility of the approach, which is is intended to be used in complete system for vision-based markerless human body tracking. Future work will aimed at optimizing the implementation, in order to achieve real-time performances

Towards better segmentation of large floating point 3D astronomical data sets:first results

In any image segmentation task, noise must be separated from the actual information and the relevant pixels grouped into objects of interest, on which measures can later be applied. This should be done efficiently on large astronomical surveys with floating point datasets with resolution of the order of Gigapixels. We illustrate in this paper how the combination of two techniques presented in previous works can help in this task. We summarise the benefits and initial outcomes of combining together a parallel algorithm to build max-trees of floating point data sets and a connected attribute filter that uses a statistical approach to identify structures due to noise and to perform segmentation on 3D radio cubes

Brain arteriovenous malformations and seizures: An Italian study

To evaluate seizures as first clinical manifestation of brain arteriovenous malformations (AVMs), in relation to angioarchitectural features of these vascular anomalies

Long-term Outcomes of Focal Cryotherapy for Low- to Intermediate-risk Prostate Cancer: Results and Matched Pair Analysis with Active Surveillance

Background: To date, only one trial compared focal therapy and active surveillance (AS) for low-risk prostate cancer (PCa). In addition, long-term outcomes of focal cryotherapy (FC) are lacking. Objective: Our aim was to evaluate long-term outcomes of FC and compare them with AS. Design, setting, and participants: We included two prospective series of 121 (FC) and 459 (AS) consecutive patients (2008-2018) for low- to intermediate-risk PCa. Outcome measurements and statistical analysis: Study outcomes were radical therapy-free or androgen deprivation therapy (ADT)-free, any treatment-free, metastasis-free, and overall survival. A matched pair analysis was performed using seven covariates. Results and limitations: The median FC follow-up was 85 mo (interquartile range 58-104); 92 (76%) men had International Society of Urological Pathology (ISUP) grade 1. Among matched variables, no significant differences were present except for cT stage and year of entry (both p 0.05), with the exception of time to radical therapy, time to radical therapy and ADT, and time to any treatment, all being shorter for AS (all p 2, n = 3); three men developed incontinence (p = 0.0814), while both International Index of Erectile Function 5 and International Prostate Symptom Score scores increased (p = 0.0287 and p = 0.0165, respectively). Limitations include absence of randomization. Conclusions: At an early long-term follow-up, FC in the context of mainly low-risk PCa is safe and increases time to radical therapy but does not provide meaningful oncological advantages compared with AS. Patient summary: We compared focal cryotherapy with active surveillance mainly for low-risk prostate cancer. Focal cryotherapy, despite having fewer complications, did not yield meaningful advantages over active surveillance at 10 yr. Active surveillance should be preferred to focal cryotherapy for these patients

Focal High-Intensity Focused Ultrasound vs. Active Surveillance for ISUP Grade 1 Prostate Cancer: Medium-Term Results of a Matched-Pair Comparison

Only 1 randomized controlled trial has compared focal therapy and active surveillance (AS) for the low-risk prostate cancer (PCa). We investigated whether focal HIFU (fHIFU) yields oncologic advantages over AS for low-risk PCa

Patterns of oral anticoagulant use and outcomes in Asian patients with atrial fibrillation: a post-hoc analysis from the GLORIA-AF Registry

Background: Previous studies suggested potential ethnic differences in the management and outcomes of atrial fibrillation (AF). We aim to analyse oral anticoagulant (OAC) prescription, discontinuation, and risk of adverse outcomes in Asian patients with AF, using data from a global prospective cohort study. Methods: From the GLORIA-AF Registry Phase II-III (November 2011-December 2014 for Phase II, and January 2014-December 2016 for Phase III), we analysed patients according to their self-reported ethnicity (Asian vs. non-Asian), as well as according to Asian subgroups (Chinese, Japanese, Korean and other Asian). Logistic regression was used to analyse OAC prescription, while the risk of OAC discontinuation and adverse outcomes were analysed through Cox-regression model. Our primary outcome was the composite of all-cause death and major adverse cardiovascular events (MACE). The original studies were registered with ClinicalTrials.gov, NCT01468701, NCT01671007, and NCT01937377. Findings: 34,421 patients were included (70.0 ± 10.5 years, 45.1% females, 6900 (20.0%) Asian: 3829 (55.5%) Chinese, 814 (11.8%) Japanese, 1964 (28.5%) Korean and 293 (4.2%) other Asian). Most of the Asian patients were recruited in Asia (n = 6701, 97.1%), while non-Asian patients were mainly recruited in Europe (n = 15,449, 56.1%) and North America (n = 8378, 30.4%). Compared to non-Asian individuals, prescription of OAC and non-vitamin K antagonist oral anticoagulant (NOAC) was lower in Asian patients (Odds Ratio [OR] and 95% Confidence Intervals (CI): 0.23 [0.22-0.25] and 0.66 [0.61-0.71], respectively), but higher in the Japanese subgroup. Asian ethnicity was also associated with higher risk of OAC discontinuation (Hazard Ratio [HR] and [95% CI]: 1.79 [1.67-1.92]), and lower risk of the primary composite outcome (HR [95% CI]: 0.86 [0.76-0.96]). Among the exploratory secondary outcomes, Asian ethnicity was associated with higher risks of thromboembolism and intracranial haemorrhage, and lower risk of major bleeding. Interpretation: Our results showed that Asian patients with AF showed suboptimal thromboembolic risk management and a specific risk profile of adverse outcomes; these differences may also reflect differences in country-specific factors. Ensuring integrated and appropriate treatment of these patients is crucial to improve their prognosis. Funding: The GLORIA-AF Registry was funded by Boehringer Ingelheim GmbH