Method and apparatus for reconstructing three-dimensional objects

A method of obtaining three-dimensional information of an object by capturing images of said object by a plurality of cameras and making three-dimensional feature points on said object to correspond to feature points in said images, said method comprising the steps:

• (a) imaging said object by n cameras to obtain n frames of images and outputting said images as image data, said n being an integer equal to or greater than 3;
• (b) receiving said image data and extracting feature points of said object on said n frames of images, respectively;
• (c) defining one of said n cameras as a basic camera, defining the other remaining cameras as reference cameras, defining the images captured by said reference cameras as reference images, and defining a backprojection line, which passes through the optical center of said basic camera and a feature point in said basic image chosen in correspondence to a noted three-dimensional feature point on said object, as a basic backprojection line;
• (d) projecting said basic backprojection line onto said reference images to define thereon epipolar lines, respectively;
• (e) defining backprojection lines, which pass through said feature points on said epipolar lines on said reference images and optical centers of said reference cameras, as reference backprojection lines;
• (f) calculating the coordinates of intersection points of said basic backprojection line and said reference backprojection lines, filtering the distribution of said intersection points along said basic backprojection line by convolution to emphasize the concentration of said distribution of said intersection points, and determining the position where said filtered distribution of the intersection points is maximum to be the position of said noted three-dimensional feature point;
• and
• (g) repeating said steps (c) through (f) for each of said feature points on said basic image to obtain the positions of said three-dimensional feature points on said object as its three-dimensional information.

A three-dimensional information reconstructing apparatus comprising:

• n camera means disposed at different positions, for capturing images of an object and for outputting said images as image data, said n being an integer equal to or greater than 3;
• and
• image information processing means supplied with said image data from said n camera means, for acquiring three-dimensional information of said object from feature points in said images;
• said image information processing means comprising:
• feature extracting means for extracting said feature points in said images;
• basic backprojection line generating means wherein one of said n camera means is defined as a basic camera, the image captured by said basic camera means as a basic image, the other remaining camera means as reference camera means, the images captured by said reference camera means as reference images, and whereby a backprojection line, which passes through the optical center of said basic camera means and a feature point in said basic image chosen in correspondence to a noted three-dimensional feature point on said object, is obtained as a basic backprojection line;
• epipolar line generating means for projecting said basic backprojection line onto said reference images to obtain epipolar lines;
• reference backprojection line generating means for obtaining, as reference backprojection lines, backprojection lines which pass through feature points on said epipolar lines on said reference images and the optical centers of said reference camera means;
• and
• three-dimensional feature extracting means for calculating the coordinates of intersection points of said basic backprojection line and said reference backprojection lines, for counting the number of intersections of said basic backprojection line and said reference backprojection lines at each of said intersection points and for determining that one of said intersection points which has the maximum count value is the position of said noted three-dimensional feature point;
• whereby the positions of respective three-dimensional feature points on said object, corresponding to respective feature points on said basic image, are obtained as said three-dimensional information of said object.

A three-dimensional information reconstructing apparatus comprising:

• n camera means disposed at difference positions, for capturing images of an object and for outputting said images as image data, said n being an integer equal to or greater than 3;
• and
• image information processing means supplied with said image data from said n camera means, for acquiring three-dimensional information of said object from feature points in said images;
• said image information processing means comprising:
• feature extracting means for extracting feature points in said images;
• basic backprojection line generating means wherein one of said n camera means is defined as a basic camera means, the image captured by said basic camera means as a basic image, the other remaining camera means as reference cameras, the images captured by said reference camera means as reference images, and whereby a backprojection line, which passes through the optical center of said basic camera means and a feature point in said basic image chosen in correspondence to a noted three-dimensional feature point on said object, is obtained as a basic backprojection line;
• epipolar line generating means for projecting said basic backprojection line onto said reference images to obtain epipolar lines;
• reference backprojection line generating means for obtaining, as reference backprojection lines, backprojection lines which pass through feature points on said epipolar lines on said reference images and the optical centers of said reference camera means;
• filtering means which calculates the coordinates of intersection points of said basic backprojection line and said reference backprojection lines, respectively, and filters the distribution of said intersection points along said basic backprojection line by convolution to emphasize the concentration of said distribution of said intersection points;
• and
• three-dimensional feature extracting means whereby the position where said filtered distribution of said intersection points is maximum is determined to the position of said noted three-dimensional feature point;
• whereby the positions of respective three-dimensional feature points on said object, corresponding to respective feature points on said basic image, are obtained as said three-dimensional information of said object.