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STRUCTURED LIGHT MATCHING OF A SET OF CURVES FROM TWO CAMERAS

  • US 20190236798A1
  • Filed: 04/11/2019
  • Published: 08/01/2019
  • Est. Priority Date: 02/05/2014
  • Status: Active Grant
First Claim
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1. A computer-implemented method performed by at least one computer processor for matching points between three images of a scene, the method including:

  • retrieving three images acquired by a sensor, said sensor comprising at least a first camera, a second camera, a third camera and a light projector unit, two images comprising a first image and a second image of the three images being acquired by respectively the first camera and the second camera and a third image being acquired by the third camera, the light projector unit projecting a projected pattern onto said scene, said three images forming a frame captured at a single relative position between the scene and the sensor, said three images each containing a reflection of the projected pattern projected by the light projector unit on said scene, wherein the projected pattern comprises at least one sheet of light, each sheet of light being labelled with a corresponding light sheet label;

    wherein the first camera, the second camera and the third camera and the light projector unit are calibrated in a common coordinate system;

    extracting blobs from said reflection in said two images and individually labeling said blobs with a unique identifier;

    for each given extracted blob of the first image;

    selecting a selected epipolar plane from a set of epipolar planes and defining a conjugate epipolar line in each of said two images, wherein the selected epipolar plane of the set of epipolar planes is defined by a center of projection of each of the first and the second cameras and an image point located on the given extracted blob;

    identifying plausible combinations, said plausible combinations including a light sheet label of said projected pattern, a unique identifier for the given extracted blob of the first image and a unique identifier for a plausible blob selected from said blobs in said second image, said plausible blob crossing the conjugate epipolar line;

    calculating a matching error for each of the plausible combinations, wherein the matching error of a given plausible combination is indicative of a proximity between intersections of each pair of three rays, wherein a first ray originates from the center of projection of the first camera and reaches the given extracted blob crossing the conjugate epipolar line in the first camera image, wherein a second ray originates from the center of projection of the second camera and reaches the plausible blob crossing the conjugate epipolar line in the second camera image and the third ray originates from a center of projection of the light projector unit and reaches an intersection between the selected epipolar plane and a corresponding sheet of light of the at least one sheet of light;

    repeating said steps of selecting, identifying and calculating for each epipolar plane of said set of epipolar planes;

    determining a most probable combination by computing a figure of merit for said plausible combinations using said matching error for each epipolar plane of said set of epipolar planes;

    identifying matching points between the two images in said frame using said determined most probable combination and the set of epipolar planes;

    validating the matching points between the two images in said frame, said validating comprising;

    for each pair of matching points located on a given epipolar plane,determining a projection of the pair of matching points in the third image of the third camera,determining if the projection of the pair of matching points in the third image of the third camera is located on a blob,identifying the pair of matching points as validated if the projection of the pair of matching points in the third image of the third camera is located on the blob;

    providing the validated pairs of matching points.

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