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Tag Archives: fitting
Gaze tracking as a novel input method
Smartphones and tablets usually have a camera on their back, to take photographs, and a frontal camera for videoconferencing. In a recent model (Samsung Galaxy S4) the frontal camera can be used as an input device too: … Continue reading
Posted in Uncategorized
Tagged computer vision, cone, digital camera, ellipse, eye, fitting, gaze tracking, iris, least squares, outlier, RANSAC, shape, smartphone, tablet
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Vanishing points in presence of noise
Most selfcalibration algorithms require a prior knowledge of the camera calibration matrix ; as an instance, you need it to normalize the image points as and therefore fit the essential matrix . With most commercial cameras it is safe to … Continue reading
Posted in Uncategorized
Tagged Alciatore and Miranda, calibration matrix, computer vision, constrained minimum, essential matrix, fitting, focal length, image of the absolute conic, Lagrange multipliers, lagrangian, least squares, noise, nonlinear regression, outlier, pixel pitch, principal point, RANSAC, vanishing point
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An alternative derivation of the DLT for homographies
What if in the linear system the unknowns are not but the matrix ? Of course, if we have a sufficient number of such systems , , … with the same matrix and independent second hands, we can stack them, and solve … Continue reading
Posted in Uncategorized
Tagged computer vision, Direct Linear Transformation, DLT, fitting, homography
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Orthogonal least squares fitting of a sphere/2
As said in my previous post, to obtain an orthogonal least squares fitting of a sphere to a cloud of points one should minimize the function Dave Eberly calls this the energy function, probably as a metaphorical reference to the … Continue reading
Orthogonal least squares fitting of a sphere
Recently I presented a linear method to obtain centre and radius of a sphere given four or more points on its surface, not all beginning to the same plane. This method is not completely satisfactory when working with more than … Continue reading
Lagrangian rejection and fitting/2
Summarizing the previous article: we have a set of samples, mostly affected by errors having a Gaussian distribution. Zero or more of the samples may be outliers, that is affected by exceptional errors which do not fit in the Gaussian … Continue reading
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Tagged constrained minimum, fitting, lagrangian multipliers, Least Trimmed Squares, LMedS, model, outlier, RANSAC, rejection, sample, shape
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Lagrangian rejection and fitting
Fitting a mathematical model to a set of samples (eg fitting a sphere to a set of 3D cartesian points supposed to lie on its surface) is not an easy task. The samples usually come from measurement and as such, … Continue reading
Posted in Uncategorized
Tagged fitting, Least Trimmed Squares, LMedS, model, outlier, RANSAC, rejection, sample, shape
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