Search results for "Three-Dimensional"

Left-Ventricle Segmentation of SPECT Images of Rats

2015

Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to…

Şeffaf cisimlerim 3B taranması

2010

Many practical tasks in industry, such as automatic inspection or robot vision, often require scanning of three-dimensional shapes with non-contact techniques. However, transparent objects, such as those made of glass, still pose difficulties for classical scanning techniques. The reconstruction of surface geometry for transparent objects is complicated by the fact that light is transmitted through, refracted and in some cases reflected by the surface. Current approaches can only deal relatively well with sub-classes of objects. The algorithms are still very specific and not generally applicable. Furthermore, many techniques require considerable acquisition effort and careful calibration. T…

L'anfiteatro romano di Termini Imerese : ricostruzioni virtuali e vicende storico/architettoniche del sito urbano

2018

The work we present is inspired by the results of an architectural survey that was carried out on the architectural remains of the Roman Amphitheater of Termini Imerese, in order to its possible conjectural reconfiguration and three-dimensional remodeling in a VRML or augmented-reality context. All this has been thought to benefit the development of cultural and archaeological tourism in the site itself. The approach to the site and to the ancient building has, however, focused on urban and territorial analysis since the first inspections, considering mainly the peculiarities that distinguish the historical / architectural vicissitudes of the site. In the Medieval Age the Jewish Quarter was…

Three-dimensional object detection under arbitrary lighting conditions

2006

A novel method of 3D object recognition independent of lighting conditions is presented. The recognition model is based on a vector space representation using an orthonormal basis generated by the Lambertian reflectance functions obtained with distant light sources. Changing the lighting conditions corresponds to multiplying the elementary images by a constant factor and because of that, all possible lighting views will be elements that belong to that vector space. The recognition method proposed is based on the calculation of the angle between the vector associated with a certain illuminated 3D object and that subspace. We define the angle in terms of linear correlations to get shift and i…

APPLICATION OF NOVEL 3D CULTURE MODELS OF HUMAN MUCOSAE TO STUDY THE EFFECTS OF ENVIRONMENTAL FACTORS ON NON-COMMUNICABLE DISEASES

2014

Periodontal health in a population with Parkinson's disease in Spain: a cross-sectional study.

2022

Background: The aim of this research is to evaluate the periodontal health of patients with Parkinson Disease (PD) in a Spanish cohort. Material and Methods: A cross-sectional study was performed on 104 patients with PD (mean age: 66.19+9.3 years) and 106 controls (mean age: 59.26+14.11 years). A pre-designed clinical protocol was implemented, which included a standardized epidemiological index for periodontal disease (CPITN), clinical attachment loss (CAL), tooth-loss, full mouth plaque index (FMPI), and oral hygienic habits. Univariate descriptions and comparative analysis were performed. Results: The majority of PD patients presented good oral hygienic habits. There were no significant d…

Some Considerations on 3-D and 2-D Numerical Models for the Assessment of the Stability of Underground Caves

2014

The application of numerical modeling to the analysis of the stability of both natural and man-made underground caves is rapidly increasing due to the availability of powerful numerical codes, that can account for either continuum or discontinuum behavior of the rock masses. Numerical methods allow to overcome traditional methods for cave stability analysis that assume too simplified geometrical, geological and geomechanical conditions. Further, they are also able to assess the potential failure mechanisms of underground systems. On the other hand, the application of numerical methods requires availability of a detailed geo-structural survey of the cave, as well as a proper geomechanical ch…

Anterolateral thigh perforator flap made by customized 3D-printing fabrication of fixed positioning guide for oromaxillofacial reconstruction:a preli…

2022

Oromaxillofacial carcinomas frequently result in serious tissue defect due to enlarged resection for treating their extensive invasion, which require challenging reconstruction. Three-dimensional (3D) printing is an advanced technology which has greatly promoted the progress of craniomaxillofacial reconstructive surgery. This present study aimed to investigate the advantages of anterolateral thigh (ALT) perforator flap manufactured by 3D printing fixed positioning guide template in curing oromaxillofacial defect. Twenty patients with oromaxillofacial defects resulted from severe primary malignant tumors were divided into experimental group assisted by digital technique (n=8) and controlled …

BIFOCAL PAIRS OF IMAGES FOR LOW-COST SURVEY IN CLOSE RANGE PHOTOGRAMMETRY

2019

Abstract. This paper present a method for close range photogrammetry based on an camera positioning scheme in which two cameras capture an equal portion of an object at the same scale, but have different focal lengths and camera-to-object distances. This scheme is alternative to the stereoscopic scheme and is associated with a system of equations which permits one to calculate first the relief displacement of points on a photograph and then their relief relative to a reference plane. The obtained relief and relief displacement values can be used to produce low-cost orthophotographs by using software for image processing, which doesn’t need to be dedicated, but has to provide measurement and…

Preconcentration and speciation analysis of mercury : 3D printed metal scavenger-based solid-phase extraction followed by analysis with inductively c…

2021

A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L−1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05 ng L−1 and 0.08 ng L−1 for MeHg and iHg, res…