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Crossing point detector, camera calibration system, crossing point detection method, camera calibration method, and recording medium

  • US 10,388,030 B2
  • Filed: 11/05/2017
  • Issued: 08/20/2019
  • Est. Priority Date: 11/18/2016
  • Status: Active Grant
First Claim
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1. A crossing point detector, comprising:

  • a memory that stores a first image, a camera imaging a checker pattern to obtain the first image, the first image including an imaged checker pattern; and

    a processor that reads out an image included in the first image from the memory, and detects a crossing point of two boundary lines in the image, whereineach of the two boundary lines is a boundary line between a first region made up of pixels having first pixel values and a second region made up of pixels having second pixel values, the second pixel values being greater than the first pixel values, the image including the first region and the second regions,the processordecides first parameters of a numerical model, the first parameters being parameters for optimizing a first evaluation value based on differences, each of the differences being provided between a pixel value given by the numerical function model and a pixel value in the image, andcomputes a position of a crossing point of two straight lines expressed by using the first parameters, and thereby detects with subpixel precision the crossing point of the two boundary lines,the numerical model is a model that, when a step edge is imaged, simulates a pixel integration effect by assigning pixel values to respective regions inside a pixel divided by a straight line, and deciding a pixel value of the overall pixel,an input to the numerical model is a pair of two-dimensional image coordinates,an output value from the model is a pixel value at the pair of two-dimensional image coordinates, andthe function model uses a curved surface that is at least first-order differentiable to express pixel values at pairs of two-dimensional image coordinates on a boundary between the first region and the second region.

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