1,721,115 research outputs found
An efficient algorithm for the nearest neighbourhood search for point clouds
No full textThis paper presents a high-performance method for the k-nearest neighbourhood search. Starting from a point cloud, first the method carries out the space division by the typical cubic grid partition of the bounding box; then a new data structure is constructed. Based on these two previous steps, an efficient implementation of the k-nearest neighbourhood is proposed. The performance of the method here presented is compared with that of the kd-tree and bd-tree algorithms taken from the ANN library as regards the computing time for some benchmarking point clouds and artificially generated test cases. The results are analysed and critically discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Geometric segmentation of 3D scanned surfaces
No full textThe geometric segmentation of a discrete geometric model obtained by the scanning of real objects is affected by various problems that make the segmentation difficult to perform without uncertainties. Certain factors, such as point location noise (coming from the acquisition process) and the coarse representation of continuous surfaces due to triangular approximations, introduce ambiguity into the recognition process of the geometric shape. To overcome these problems, a new method for geometric point identification and surface segmentation is proposed. The point classification is based on a fuzzy parameterization using three shape indexes: the smoothness indicator, shape index and flatness index. A total of 11 fuzzy domain intervals have been identified and comprise sharp edges, defective zones and 10 different types of regular points. For each point of the discrete surface, the related membership functions are dynamically evaluated to be adapted to consider, point by point, those properties of the geometric model that affects uncertainty in point type attribution. The methodology has been verified in many test cases designed to represent critical conditions for any method in geometric recognition and has been compared with one of the most robust methods described in the related literature
A review on decision-making methods in engineering design for the automotive industry
No full textDecision-making methods have proven to be an effective support to
engineering design. However, it is proved that very often designers
prefer tested procedures and experience-based approaches. Many
reasons have been discussed in the literature, dealing with consolidated
design habits of people and companies, high cost in terms
of time consumption, and lack of tools and knowledge. The paper
systematically investigates, through an extended critical review, how
decision-making methods can be used by automotive designers to
solve the most common engineering problems involved along the
design process. In particular, the paper proposes an original classification
of the most widely used decision-making methods in engineering
design, a match between such techniques with the typical
design phases, and a mapping of their application into the automotive
field. This research can be considered as a further step to
transfer the state-of-the-art knowledge on decision- making methods
to the industrial context, establishing a common background for
practitioners and researchers
Sviluppo di una primitiva geometrica per la modellazione di profili alari in ambiente CAD
No full text
A new method for the automatic identification of the dimensional features of vertebrae
No full textIn this paper a new automatic approach to determine the accurate measure of human vertebrae is proposed. The aim is to speed up the measurement process and to reduce the uncertainties that typically affect the measurement carried out by traditional approaches. The proposed method uses a 3D model of the vertebra obtained from CT-scans or 3D scanning, from which some characteristic dimensions are detected. For this purpose, specific rules to identify morphological features, from which to detect dimensional features unambiguously and accurately, are put forward and implemented in original software. The automatic method which is here proposed is verified by analysing real vertebrae and is then compared with the state-of-the-art methods for vertebra measurement
C1 CONTINUITIES DETECTION IN TRIANGULAR MESHES
No full textThe identification of C1 continuities is important in many applications involving point clouds or triangular
meshes, such as surface segmentation, inspection and rendering. The methods in literature have some
limitations which make them strongly dependent on some properties of the mesh (point typology, mesh
resolution, uniformity of the shape of triangles and error in point location). Furthermore, some of them
do not discriminate non-regular points from those that are inside a band around them.
In this work, a new method for automatic detection of C1 continuities in triangular meshes is presented.
The method introduces an original function, called sharpness indicator, which enables us to evaluate
properties related to surface smoothness. The performance of the new method is compared with that
of four methods presented in literature as regards the recognition of C1 continuities both in synthetic and
real meshes. Results are analysed and critically discussed
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