Sensor architectures and technologies for upper limb 3d surface reconstruction: A review

3D digital models of the upper limb anatomy represent the starting point for the design process of bespoke devices, such as orthoses and prostheses, which can be modeled on the actual patient’s anatomy by using CAD (Computer Aided Design) tools. The ongoing research on optical scanning methodologies has allowed the development of technologies that allow the surface reconstruction of the upper limb anatomy through procedures characterized by minimum discomfort for the patient. However, the 3D optical scanning of upper limbs is a complex task that requires solving problematic aspects, such as the difficulty of keeping the hand in a stable position and the presence of artefacts due to involuntary movements. Scientific literature, indeed, investigated different approaches in this regard by either integrating commercial devices, to create customized sensor architectures, or by developing innovative 3D acquisition techniques. The present work is aimed at presenting an overview of the state of the art of optical technologies and sensor architectures for the surface acquisition of upper limb anatomies. The review analyzes the working principles at the basis of existing devices and proposes a categorization of the approaches based on handling, pre/post-processing effort, and potentialities in real-time scanning. An in-depth analysis of strengths and weaknesses of the approaches proposed by the research community is also provided to give valuable support in selecting the most appropriate solution for the specific application to be addressed

Which is the most accurate diagnostic procedure in Tamoxifen treated breast cancer patients

Purpose: The aim of this study was to evaluate the diagnostic accuracy of bi-dimensional (2D) and three-dimensional (3D) transvaginal ultrasound (TVUS), hysterosonography (HSSG) and hysteroscopy in the detection of endometrial pathology in women treated with tamoxifen (TMX) for breast cancer. Methods: Forty-two patients, affected by breast cancer under treatment with TMX, underwent 2D-3D TVUS, HSSG and hysteroscopy completed by biopsy, after abnormal findings following a routine 2D TVUS examination. Results: 3D-TVUS was more accurate than 2D-TVUS in the detection of atrophic endometrium confirmed by biopsy and in the detection of endometrial polyps. HSSG and hysteroscopy detected atrophic endometrium and endometrial polyps significantly better than ultrasound scan. Endometrial carcinoma was detected in two cases, and in both HSSG and hysteroscopy were 100% diagnostic. Conclusion: In TMX treated breast cancer patients, HSSG and hysteroscopy provide more accurate diagnosis than 2D-3D ultrasound in the detection of treatment related endometrial lesions

3D Maxillofacial Model Creation for Computer-guided Treatments in Oral Rehabilitation

Recent advances in 3D imaging techniques have provided flexible tools for clinical assessments within many medical fields. In the field of orthodontic and orthognathic surgery, the reliable creation of 3D anatomical models can assist clinicians for both diagnosis and treatment planning. In particular, the accurate integration between facial soft tissue, facial skeleton and dentition (maxillofacial triad) provides clinicians with a complete model for virtual 3D treatment planning. However, none of the existing imaging technologies is able to simultaneously capture the complete triad with the optimal resolution and accuracy. For this reason, a “model fusion” process must be carried out in order to integrate 3D models obtained using different imaging techniques. This paper aims at introducing a procedure to create accurate maxillofacial triad models by guiding the fusion of multi-modal 3D imaging techniques. The methodology is based on integrating a structured light optical scanner with Cone-Beam Computed Tomography (CBCT) data processing in order to capture the different tissue groups composing the maxillofacial triad. The generated models represent an all-embracing virtual workbench for orthodontists in the treatment planning of malocclusion problems and for surgeons in the preoperative prediction of surgical outcomes

Fast Digitizing of 3D Shapes by Automatic Alignment of Multiple Range Maps

Range maps registration still represents one of the most time consuming phases in the digitization of 3D shapes due to the high user intervention required. The traditional approaches are, in fact, based on manual rough alignments, followed by ICP refining techniques. On the other hand, existing unattended meth-odologies, based on the automatic searching for correspondent morphological singularities on adjacent point clouds, do not seem to guarantee sufficient robustness and flexibility in the fast reconstruction of target ob-jects. This paper presents a methodology to acquire free-form shapes by combining a 3D stereo vision system and a fully automatic range maps registration process. The automatic alignment is carried out without any as-sumptions about the initial positions of the point clouds and is based on the automatic detection of fiducial markers, located on the surface object, by processing grey intensity images

Verifica sperimentale di un sistema a luce strutturata per il rilievo di forma

L’attività di ricerca descritta in questo lavoro è focalizzata sulla messa a punto di un sensore ottico per la determinazione di un insieme di punti ordinati appartenenti alla superficie di un oggetto reale. Il sistema utilizza una soluzione innovativa del metodo gray-code basata su un processo di doppia codifica delle immagini acquisite con una coppia di telecamere digitali. La metodologia risolve il problema della correlazione dei dati misurati nelle immagini acquisite con il sistema di visione stereo utilizzando luce strutturata comprendente frange orizzontali e verticali codificate. Questo approccio consente di utilizzare proiettori multimediali convenzionali senza pregiudicare la precisione di misura. In questo lavoro, le prestazioni del sistema ottico sono state valutate mediante l’analisi sperimentale di alcune grandezze d’influenza in un ambiente controllato e il rilievo di un prototipo di vettura sportiva in un contesto industriale

Low-speed cameras system for 3D-DIC vibration measurements in the kHz range

The digital image correlation (DIC) was used in this paper to obtain full-field measurements of a target vibrating at a frequency higher than the maximum cameras’ frame rate. The down-sampling technique was implemented to compensate for the cameras’ moderate frame rate, thus getting an accurate displacement acquisition even at 6.5 kHz. Two innovative methods to support the DIC application were introduced. The use of fringe projection (or structured light), initially applied on the sample at rest, reduced the effort and time required for the stereo matching task's solution and improved this setting's accuracy and reliability. Additionally, a new time-domain image filtering was proposed and tested to improve the quality of the obtained DIC maps. In combination with the down-sampling, the effect of this filtering technique was tested in this work at (approx.) 2500 and 6500 Hz by measuring the response of a bladed disk to sinusoidal excitation. Evidence of improved results was observed for both frequencies for amplitudes in the range of 10 µm

Structured light stereo catadioptric scanner based on a spherical mirror

The present paper describes the development and characterization of a structured light stereo catadioptric scan- ner for the omnidirectional reconstruction of internal surfaces. The proposed approach integrates two digital cameras, a multimedia projector and a spherical mirror, which is used to project the structured light patterns generated by the light emitter and, at the same time, to reflect into the cameras the modulated fringe patterns diffused from the target surface. The adopted optical setup defines a non-central catadioptric system, thus relax- ing any geometrical constraint in the relative placement between optical devices. An analytical solution for the reflection on a spherical surface is proposed with the aim at modelling forward and backward projection tasks for a non-central catadioptric setup. The feasibility of the proposed active catadioptric scanner has been verified by reconstructing various target surfaces. Results demonstrated a great influence of the target surface distance from the mirror’s centre on the measurement accuracy. The adopted optical configuration allows the definition of a metrological 3D scanner for surfaces disposed within 120 mm from the mirror centre

Post-processing treatments to enhance additively manufactured polymeric parts: a review

The potential of additive manufacturing to produce optimised and customized polymeric parts is often impaired by poor surface finish, low mechanical properties, and insufficient dimensional accuracy. Post-processing treatments are usually adopted to address these issues. Scientific community and industrial actors are engaged in the development and use of post-processing to enhance the performance and widen the range of application of polymeric components manufactured by additive technologies. The present work aims to provide an exhaustive classification and discussion of the post-processing treatments, as well as an extensive literature review of the approaches proposed within the scientific community. A holistic view of post-processing is provided, including a discussion of the benefits associated with each technique as well as its side effects. This work is intended to support the selection of the most appropriate post-processing by considering multiple aspects such as the material, part geometry, processing time, costs, and treatment specificity

Automatic technical documentation of lithic artefacts by digital techniques

Despite the existence of a wide variety of standards to create hand-made illustrations of lithic artefacts, the conventional process is laborious, time-consuming and the quality of the drawings is highly variable. In this paper, a novel computer-based methodology to create automatic technical documentation of lithic artefacts, in the form of manual-like drawings, is presented. The method exploits the artefact digital model obtained by a 3D optical scanner. An optimization process is proposed to orient the digital model reproducing the conventional positioning. A lighting model is used to introduce an illumination source having different directions, to highlight surface details. A set of images is then created and segmented to retrieve the artefact outline and the internal ridges between flake scars. Potentialities of the proposed methodology are illustrated by analyzing three different stone artefacts acquired by a structured light scanner. 2D technological drawings are automatically created and compared to those obtained by an experienced lithic illustrator