1,721,145 research outputs found
A portable modular system for automatic acquisition of 3D objects
No full textA portable and flexible system for three-dimensional (3D) scanning is presented. It is constituted of four main modules. The first module is devoted to the acquisition of a set of 3-D points over the surface through laser scanning (digitization). The second module reconstructs a continuous 3D surface, filtering the measurement noise. Whenever required (e.g., in CAD applications), a third module converts the surface into a 3D mesh which can then be colored by projecting over it a bitmap or the surface, obtained from a snapshot to obtain a highly realistic textured 3D model. This instrument improves upon the commercially available scanners in two main aspects. The digitizer proves to be highly flexible and accurate, and it can easily accommodate objects of different dimension. The construction of the surface and the filtering of the digitization noise are performed in a single step through a fully adaptive algorithm which produces a multiscale surface and can be parallelized to work in real time. Results on the reproduction of human faces are reported and discussed
Tomosynthesis through a time delay integration sensor
No full textComputerized tomography is nowadays largely diffused; however, the high radiation dose delivered to the patient tissue and the elevated cost of the tomographic apparatus are often not justified for the applications of the clinical dental field (e.g. implantology). Here we propose to use a traditional ortopantomograph, which is equipped with a cheap, linear sensor, to acquire a set of projections from a limited angle of view; from these projections, the volume of interest is reconstructed through tomosynthesis and successively deblurred. The encouraging results illustrated here demonstrate the feasibility of the approach, which may open the door to a superior class of multifunction ortopantomographs
Studio comparativo fra bufali e bovini alimentati con fieno e mangime concentrato composto. XIV. Colore della carne all'età di 64 settimane.
No full text
Multi-resolution models for data processing : an experimental sensitivity analysis
No full textHierarchical Radial Basis Functions Networks
(HRBF) have been recently introduced as a tool for adaptive multiscale image reconstruction from range data.
They are based on local operation on the data and are able to give a sparse approximation. In this paper HRBF are
reframed for the regular sampling case, and they are compared with Wavelet Decomposition. Results show that HRBF, thanks to their constructive approach to
approximation, are much more tolerant on errors on the parameters when errors occurs in the configuration phase, while they are more sensitive to the errors which occurs
since the network has been configured
Real-time surface reconstruction through HRBF networks
No full textA procedure for 3D surface reconstruction from range data in strict real-time is presented. The process is based on a connectionist model, the hierarchical radial basis function (HRBF) network, which has been proved to be effective in the reconstruction of smooth, space varying surfaces. An efficient data structure and locality assumptions allowed the derivation of a faster configuration algorithm, without degrading the approximation capabilities. Results show that computing time scales linearly with the number of neurons, and is comparable with the data acquisition time of most commercial scanners so that reconstruction can be performed in real time
A new and reliable Poisson noise estimator for radiographic images
No full textDigital images in general, and radiographies in particular, are mainly affected by photon counting noise. In this paper, we provide a method to estimate the gain of the imaging sensor and the variance of the photon counting noise associated to each image grey level. This is useful to multiple scopes, like reverse engineering and denoising
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