Parameter estimation apparatus, parameter estimation method, and computer-readable recording medium

A method for calculating a threshold for separating a plurality of data points into outliers and inliers and estimating a parameter fitting the inliers, the method, performed by a computer, comprising:

• (a) estimating the parameter by using the plurality of data points as input;
• (b) calculating the threshold based on statistical information of residuals of the plurality of data points;
• and
• (c) determining whether or not convergence of the estimation of the parameter is reached based on the estimated parameter and the calculated threshold, wherein the (a) and the (b) are each executed again if it is determined in the (c) that convergence is not reached;
• the method further comprising:
• (d) acquiring the plurality of data points and an initial value of the parameter and calculating residuals of the plurality of data points relative to the acquired initial value;
• and
• (e) based on the calculated residuals, updating weights assigned to the plurality of data points, wherein
• in the (a), the parameter is estimated by also using, as input, the weights of the plurality of data points updated in the (e) in addition to the plurality of data points,
• in the (b), residuals of the inliers, from among the residuals calculated in the (d), are specified and the threshold is calculated based on the statistical information of the specified residuals of the inliers,
• if it is determined in the (c) that convergence is reached, the estimated parameter is output as a parameter fitting the inliers in the (c), and
• if it is determined in the (c) that convergence is not reached, the parameter estimated in the (a) step is set as the initial value and the (d), the (e), the (a), and the (b) are each executed again.

A non-transitory computer readable recording medium that includes a program recorded thereon that causes a computer to calculate a threshold for separating a plurality of data points into outliers and inliers and estimate a parameter fitting the inliers, the program including instructions that causes a computer to carry out:

• (a) a step of estimating the parameter by using the plurality of data points as input;
• (b) a step of calculating the threshold based on statistical information of residuals of the plurality of data points;
• and
• (c) a step of determining whether or not convergence of the estimation of the parameter is reached based on the estimated parameter and the calculated threshold, and the (a) step and the (b) step are each executed again if it is determined in the (c) step that convergence is not reached;
• the program further incudes instructions that cause the computer to carry out:
• (d) a step of acquiring the plurality of data points and an initial value of the parameter and calculating residuals of the plurality of data points relative to the acquired initial value;
• and
• (e) a step of, based on the calculated residuals, updating weights assigned to the plurality of data points, in the (a) step, the parameter is estimated by also using, as input, the weights of the plurality of data points updated in the (e) step in addition to the plurality of data points, in the (b) step, residuals of the inliers, from among the residuals calculated in the (d) step, are specified and the threshold is calculated based on the statistical information of the specified residuals of the inliers, if it is determined in the (c) step that convergence is reached, the estimated parameter is output as a parameter fitting the inliers in the (c) step, and if it is determined in the (c) step that convergence is not reached, the parameter estimated in the (a) step is set as the initial value and the (d) step, the (e) step, the (a) step, and the (b) step are each executed again.