G. Di Leo

A New Calibration Procedure for 3-D Shape Measurement System Based on Phase-Shifting Projected Fringe Profilometry

An original procedure is presented for the calibration of fringe-projection-based 3-D vision systems. The proposed approach estimates both the phase-to-depth and transverse relationships by directly measuring the phase maps for only three planes placed within the calibration volume and then estimating the phase maps for a number of other ldquovirtual planes.rdquo Experimental tests conducted on a fringe projection system show the effectiveness of the proposed procedure.

An improved procedure for the automatic detection of dermoscopic structures in digital ELM images of skin lesions

Early detection of melanoma is a very critical issue in todaypsilas dermatologic practice. Different diagnostic methods have been proposed which define multiple criteria for the evaluation of the malignancy of a lesion. The paper is devoted to the detection of an important dermatologic structure: the atypical pigmented network. A proposal is described for the application of decision-tree classification techniques to the results of specific image processing algorithms for the estimation of chromatic and structural parameters.

Covariance Propagation for the Uncertainty Estimation in Stereo Vision

Stereo vision has emerged as an effective approach for contactless 3-D measurements. This paper presents a methodology for the propagation of the measurement uncertainty through stereo-vision calibration and measurement algorithms, according to international standards. The proposed procedure is compared to the reference statistical procedure for uncertainty evaluation, and the results are presented and discussed. The results proved that the proposed procedure was able to estimate the standard uncertainty even at considerable working distances from the calibrated volume with negligible processing times and far more accurately than the theoretical simplified models commonly adopted.

A software tool for the diagnosis of melanomas

Early detection of melanoma is one of the greatest challenges of dermatologic practice today. A new diagnostic method, the “ELM 7 point checklist”, defines a set of seven features, based on colour and texture parameters, which describe the malignancy of a lesion. It has been presented as faster and with the same accuracy than the traditional ABCD criteria in the diagnosis of melanoma. In this paper a new system for automated diagnosis of melanocytic skin lesions, based on ELM 7 point checklist, is introduced.

Uncertainty evaluation of camera model parameters

Camera calibration is an important task for vision-based measurement systems since it estimates the values of camera model parameters. The uncertainty of these parameters is required in order to evaluate the uncertainty of vision-based final measurements. This paper deals with a procedure for the propagation of the uncertainty through calibration algorithms and mainly focuses on the algorithms for the localization of target points in calibration images. Numerical results will be reported highlighting the usefulness of the method in the set-up of a vision-based measurement system.

Propagation of uncertainty through stereo triangulation

Stereo-vision has emerged as an effective approach for contact-less three-dimensional measurements. This paper presents a methodology for the propagation of the measurement uncertainty through stereo-vision calibration and measurement algorithms, according to international standards. The proposed procedure is compared to reference statistical procedure for uncertainty evaluation and results are presented and discussed.

A simplified procedure for the calibration of a fringe pattern profilometer

The paper proposes a calibration technique for the evaluation of the phase necessary for the operation of a 3-D scanner based on sinusoidal fringe projections. The calibration requires the acquisition of images of a target plane positioned at only two parallel poses and evaluates the phase values at intermediate positions through linear interpolation. The calibration procedure is described in detail together with the results of a number of tests aiming to evaluate the goodness of the linear approximation.

Metrological verification of 3D scanners: a preliminary approach

The paper deals with the metrological characterization of 3D scanners, and proposes a procedure for their experimental verification in accord with the suggestions of the ISO GUM. The procedure is based on the application of a statistical method for the evaluation of the standard uncertainty to the results of a comparison with a Coordinate Measuring Machine (CMM). Finally the results of the experimental verification of a fringe pattern system are reported and discussed in detail.

Self-calibration for a camera-projector pair

A self-calibration algorithm has been designed and evaluated for the calibration of a structured-light 3-D scanner based on a camera - projector pair. It aims to allow the quick calibration on the field of a reconfigurable pair which has already been calibrated accurately in laboratory. The calibration is based on the minimization of the epipolar error. Numerical and experimental tests show the correctness of the followed approach.

Metrological Performance of Traffic Detection Systems

All of the more advanced traffic management techniques base their efficiency on reliable traffic detection systems. In a very important and emerging field, where the technical solutions proposed to measure and collect traffic primary data are not few, a unique methodology to evaluate and compare their performance still misses. In this paper, the problem of the metrological characterization of traffic detection systems is widely treated, founding inspiration on the ISO Guide to Uncertainty in Measurement. Experimental results are reported to demonstrate the applicability of the suggested procedure to some commercial instruments.