Three-dimensional body scanning: methods and applications for anthropometry

In questa tesi descriviamo i metodi informatici e gli esperimenti eseguiti per l\u2019applicazione della tecnologia whole body 3D scanner in supporto dell\u2019antropometria. I body scanner restituiscono in uscita una nuvola di punti, solitamente trasformata in mesh triangolare mediante l\u2019uso di algoritmi specifici per supportare la visualizzazione 3D della superficie e l\u2019estrazione di misure e landmarks antropometrici significativi. L\u2019antropometria digitale \ue8 gi\ue0 stata utilizzata con successo in vari studi per valutare importanti parametri medici. L\u2019analisi antropometrica digitale \ue8 solitamente eseguita utilizzando soluzioni software fornite dai costruttori che sono chiuse e specifiche per il prodotto, che richiedono attenzione nell\u2019acquisizione e dei forti limiti sulla posa assunta dal soggetto. Questo pu\uf2 portare a dei problemi nella comparazione di dati acquisiti in diversi luoghi, nella realizzazione di studi multicentrici su larga scala e nell\u2019applicazione di metodi avanzati di shape analysis sui modelli acquisiti. L\u2019obiettivo del nostro lavoro \ue8 di superare questi problemi selezionando e personalizzando strumenti di processing geometrico capaci di creare un sistema aperto ed indipendente dallo strumento per l\u2019analisi di dati da body scanner. Abbiamo inoltre sviluppato e validato dei metodi per estrarre automaticamente dei punti caratteristici, segmenti corporei e misure significative che possono essere utilizzate nella ricerca antropometrica e metabolica. Nello specifico, presentiamo tre esperimenti. Nel primo, utilizzando uno specifico software per l\u2019antropometria digitale, abbiamo valutato la performance dello scanner Breuckmann BodySCAN nelle misure antropometriche. I soggetti degli esperimenti sono 12 giovani adulti che sono stati sottoposti procedure di antropometria manuale e digitale tridimensionale (25 misurazioni) indossando abbigliamento intimo attillato. Le misure duplicate effettuate da un\u2019antropometrista esperto mostrano una correlazione r=0.975-0.999; la loro media \ue8 significativamente (secondo il test t di Student) diversa su 4 delle 25 misure. Le misure digitali effettuate in duplicato da un antropometrista esperto e da due antropometristi non esperti, mostrano indici di correlazione individuali r che variano nel range 0.975-0.999 e medie che che erano significativamente diverse in una misurazione su 25. La maggior parte delle misure effettuate dall\u2019antropometrista esperto, manuali e digitali, mostrano una correlazione significativa (coefficiente di correlazione intra-classe che variano nell\u2019intervallo 0.855-0.995, p<0.0001). Concludiamo che lo scanner Breuckmann BodySCAN \ue8 uno strumento affidabile ed efficace per le misure antropometriche. In un secondo esperimento, compariamo alcune caratteristiche geometriche facilmente misurabili ottenute dalle scansioni di femmine obese (BMI>30) con i parametri di composizione corporea (misurata con una DXA) dei soggetti stessi, per investigare quali misure dei descrittori di forma correlavano meglio con il grasso del torso e corporeo. I risultati ottenuti mostrano che alcuni dei parametri geometrici testati presentano una elevata correlazione, mentre altri non correlano fortemente con il grasso corporeo. Questi risultati supportano il ruolo dell\u2019antropometria digitale nell\u2019indagine sulle caratteristiche fisiche rilevanti per la salute, ed incoraggiano la realizzazione di ulteriori studi che analizzino la relazione tra descrittori di forma e composizione corporea. Infine, presentiamo un nuovo metodo per caratterizzare le superfici tridimensionali mediante il calcolo di una funzione chiamata \u201cArea projection transform\u201d, la quale misura la possibilit\ue0 dei punti dello spazio 3D di essere il centro di simmetria radiale della forma a predeterminati raggi. La trasformata pu\uf2 essere usata per rilevare e caratterizzare in maniera robusta i regioni salienti (approssimativamente parti sferiche e cilindriche) ed \ue8, quindi, adatta ad applicazioni come la detection di caratteristiche anatomiche. In particolare, mostriamo che \ue8 possibile costruire grafi che uniscono questi punti seguendo i valori massimali della MAPT (Radial Simmetry Graphs) e che questi grafi possono essere usati per estrarre rilevanti propriet\ue0 della forma o definire corrispondenze puntuali robuste nei confronti di problematiche quali parti mancanti, rumore topologico e deformazioni articolate. Concludiamo che le potenziali applicazioni della tecnologia della scansione tridimensionale applicata all\u2019antropometria sono innumerevoli, limitate solo dall\u2019abilit\ue0 della conoscienza scientifica di connettere il fenomeno biologico con le appropriate descrizioni matematiche/geometriche.In this thesis we describe the developed computer method and experiments performed in order to apply whole body 3D scanner technology in support to anthropometry. The output of whole body scanners is a cloud of points, usually transformed in a triangulated mesh through the use of specific algorithms in order to support the 3D visualization of the surface and the extraction of meaningful anthropometric landmarks and measurements. Digital anthropometry has been already used in various studies to assess important health-related parameters. Digital anthropometric analysis is usually performed using device-specific and closed software solutions provided by scanner manufacturers, and requires often a careful acquisition, with strong constraints on subject pose. This may create problems in comparing data acquired in different places and performing large-scale multi-centric studies as well as in applying advanced shape analysis tools on the captured models. The aim of our work is to overcome these problems by selecting and customizing geometrical processing tools able to create an open and device-independent method for the analysis of body scanner data. We also developed and validated methods to extract automatically feature points, body segments and relevant measurements that can be used in anthropometric and metabolic research. In particular we present three experiments. In the first, using specific digital anthropometry software, we evaluated the Breuckmann BodySCAN for performance in anthropometric measurement. Subjects of the experiment were 12 young adults underwent both manual and 3D digital anthropometry (25 measurements) wearing close-fitting underwear. Duplicated manual measurement taken by one experienced anthropometrist showed correlation r 0.975-0.999; their means were significantly different in four out of 25 measurements by Student\u2019s t test. Duplicate digital measurements taken by one experienced anthropometrist and two na\uefve anthropometrists showed individual correlation coefficients r ranging 0.975-0.999 and means were significantly different in one out of 25 measurements. Most measurements taken by the experienced anthropometrist in the manual and digital mode showed significant correlation (intraclass correlation coefficient ranging 0.855-0.995, p<0.0001). We conclude that the Breuckmann BodyScan is reliable and effective tool for digital anthropometry. In a second experiment, we compare easily detectable geometrical features obtained from 3D scans of female obese (BMI > 30) subjects with body composition (measured with a DXA device) of the same subjects, in order to investigate which measurements on shape descriptors better correlate with torso and body fat. The results obtained show that some of the tested geometrical parameters have a relevant correlation, while other ones do not strongly correlate with body fat. These results support the role of digital anthropometry in investigating health-related physical characteristics and encourage the realization of further studies analyzing the relationships between shape descriptors and body composition. Finally, we present a novel method to characterize 3D surfaces through the computation of a function called Area Projection Transform, measuring the likelihood of points in the 3D space to be center of radial symmetry at selected scales (radii). The transform can be used to detect and characterize robustly salient regions (approximately spherical and cylindrical parts) and it is, therefore, suitable for applications like anatomical features detection. In particular, we show that it is possible to build graphs joining these points following maximal values of the MAPT (Radial Symmetry Graphs) and that these graphs can be used to extract relevant shape properties or to establish point correspondences on models robustly against holes, topological noise and articulated deformations. It is concluded that whole body scanning technology application to anthropometry are potentially countless, limited only by the ability of science to connect the biological phenomenon with the appropriate mathematical/geometrical descriptions

Investigating carbon materials nanostructure using image orientation statistics

International audienceA new characterization method of the lattice fringe images of turbostratic carbons is proposed. This method is based on the computation of their orientation field without explicit detection of fringes. It allows meaningful insights into the material nanostructure and nanotexture at several scales, either qualitatively or quantitatively. The calculation of pairwise spatial statistics of the orientation field at short distance provides measurements of the coherence lengths along any direction, in particular along and orthogonally to the layers. These statistics also allow representing orientation coherence patterns typical of the observed nanostructure. At larger distances, the mean disorientation of the fringes is computed and information about the homogeneity of the sample is obtained. An experimental validation is carried out on various artificial images and an application to the characterization of four bulk turbostratic carbons is provided

Retrieval and classification methods for textured 3D models: a comparative study

International audienceThis paper presents a comparative study of six methods for the retrieval and classification of tex-tured 3D models, which have been selected as representative of the state of the art. To better analyse and control how methods deal with specific classes of geometric and texture deformations, we built a collection of 572 synthetic textured mesh models, in which each class includes multiple texture and geometric modifications of a small set of null models. Results show a challenging, yet lively, scenario and also reveal interesting insights in how to deal with texture information according to different approaches, possibly working in the CIELab as well as in modifications of the RGB colour space

Automated characterization of Tumor-Infiltrating Lymphocytes (TIL) in histological breast images

Cancer illness has a big influence on society. Its extended proliferation and high aggressiveness make it a difficult problem to solve and therefore a big deal for science. Recently, a research trend has been focusing on how 3D tumor structure affects the development of the cancer and its outcome, especially metastasis. Stromal structure and tumor cell signaling are processes that highly influence tumor migration. Thus, histological analysis becomes a fundamental tool to study tumor structure, which provides valuable information about cell characteristics and organization. The relevance of histological study is supported by the increasing interest of anatomopathologists to have good automatic solutions to support the specialist’s diagnosis. For this purpose, the current thesis proposes an automated approach to analyze hematoxylin and eosin (H&E) stained histological images, particularly coming from breast cancer patients. The proposed method consists on the classification of the nuclei in H&E-stained histological images and the further analysis of tumor-infiltrating lymphocytes (TIL) present on the visualized section. The starting point of the approach is the automatic nuclei-segmented binary mask. Each of the segmented nuclei is classified into two types, cancerous or healthy. The classification is performed by a trained artificial neural network to give two binary masks, each of them containing one type of nuclei. Then, the algorithm can follow two different paths: classification of zones or TIL analysis. Classification of zones has the aim to provide a more comfortable support to perform cancer diagnosis, because it provides quantitative information of tumor lobule size. To achieve it, a nuclei correction step is executed, by which each nucleus class depends on the area surrounding it. In this way, a clearer vision of the existing zones is provided (tumor lobule or tumor microenvironment). The other approach is to perform TIL analysis. This technique is based on the nuclei classified binary masks and analyzes the immune system response against the tumor. This way, healthy cells of tumor microenvironment are detected and quantified. The ratio of TIL occupied area to free microenvironment area is computed as informational parameter. This ratio is calculated by the combination of a manually-segmented zone binary mask and the nuclei classified binary mask. In this way, only healthy nuclei of microenvironment zone are considered, dividing the sum of their area by the free sections of the microenvironment zone (i.e. area of microenvironment zone where nuclei are not present). Moreover, the TIL dispersion factor is computed to study their distribution throughout the area by dividing the microenvironment area in several zones and calculate the standard deviation of the area of lymphocytes within each of them. Afterward, the opposed of standard deviation is computed to obtain the dispersion factor. Automatic results are found to match the gold standard (the pathologist’s diagnosis), although some error is observed after evaluation. The approach taken in this work has a positive outlook, even though some aspects need to be polished, like the algorithm accuracy and the use of a larger set of images to claim a proper functionality for global cases.Ingeniería Biomédic

Multiscale characterizations of surface anisotropies

Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a EDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies