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

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Vanishing points in presence of noise

Most self-calibration 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

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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

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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

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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

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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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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

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