Method for reconstructing a three-dimensional surface of an object

Method for determining disparity value of a disparity of a point on an object being detected by at least one image detector, according to a stereoscopic color image pair of the object, the point being represented by a plurality of pixels in each image of the stereoscopic color image pair, the method comprising the procedures of:

• producing a first set of distortion-corrected color images respective of each of a plurality of colors of said at least one image detector, by applying an image distortion correction model to a first distorted image among said stereoscopic color image pair;
• producing a second set of distortion-corrected color images respective of said colors, by applying said image distortion correction model to a second distorted image among said stereoscopic color image pair;
• producing a set of modified images by determining at least one interpolated pixel between every two adjacent actual pixels in each row of each of said distortion-corrected color images of said second set of distortion-corrected color images;
• determining a distance range between said object and said at least one image detector;
• determining a disparity range respective of said stereoscopic color image pair, according to said distance range;
• defining a window of a predetermined size around an actual pixel in each of said distortion-corrected color images of said first set of distortion-corrected color images;
• defining a plurality of windows around a plurality of central pixels in each of said modified images, the size of each of said windows being the same as said predetermined size, said central pixels having the same row indices respective of the row of said actual pixel, and a plurality of column indices within said disparity range from the column index of said actual pixel;
• determining a plurality of color intensity distribution differences between the color intensity distribution of said window and each of said windows;
• selecting a minimum color intensity distribution difference among said color intensity distribution differences;
• selecting a central pixel among said central pixels, as a pixel which matches said actual pixel, said central pixel corresponding to a selected window among said windows, said selected window corresponding to said minimum color intensity distribution difference;
• and
• determining said disparity value according to a difference between the coordinates of said actual pixel and of said selected central pixel.

Method for determining a disparity value of a disparity of a point on an object being detected by at least one image detector, according to a stereoscopic color image pair of the object, the point being represented by a plurality of pixels in each image of the stereoscopic color image pair, the method comprising the procedures of:

• producing a first set of distortion-corrected color images respective of each of a plurality of colors of said at least one image detector, by applying an image distortion correction model to a first distorted image among said stereoscopic color image pair;
• producing a second set of distortion-corrected color images respective of said colors, by applying said image distortion correction model to a second distorted image among said stereoscopic color image pair;
• applying a first filter to each of said distortion-corrected color images in said first set and in said second set;
• producing a set of modified images by determining at least one interpolated pixel between every two adjacent actual pixels in each row of each of said filtered distortion-corrected color images of said second set of distortion-corrected color images;
• determining a distance range between said object and said at least one image detector;
• determining a disparity range respective of said stereoscopic color image pair, according to said distance range;
• defining a window of a predetermined size around an actual pixel in each of said distortion-corrected color images of said first set of distortion-corrected color images;
• defining a plurality of windows around a plurality of central pixels in each of said modified images, the size of each of said windows being the same as said predetermined size, said central pixels having the same row indices respective of the row of said actual pixel, and a plurality of column indices within said disparity range from the column index of said actual pixel;
• determining a linear function of an absolute value of vectorial gradients, of another absolute value of vectorial gradient differences, and of the absolute value of the difference between color image intensities, respective of said window and of respective ones of each of said windows;
• selecting a minimum value among said linear functions;
• selecting a central pixel among said central pixels, as a pixel which matches said actual pixel, said central pixel corresponding to a selected window among said windows, said selected window corresponding to said selected minimum value;
• and
• determining said disparity value according to a difference between the coordinates of said actual pixel and of said selected central pixel.

Method for determining a center of distortion of a first distorted image and a second distorted image of a target, the method comprising the procedures of:

• determining two-dimensional coordinates of a plurality of known points of said target, in said first distorted image and in said second distorted image;
• correcting two-dimensional locations of said two-dimensional coordinates, in said first distorted image and in said second distorted image, according to an image distortion correction model, whose origin is selected as an image detector center;
• determining a first transformation model and a second transformation model, according to respective ones of said corrected two-dimensional locations, and according to three-dimensional coordinates of said known points;
• determining a first set of calculated points and a second set of calculated points, by applying said first transformation model and said second transformation model, respectively, to said three-dimensional coordinates;
• determining a first set of distorted calculated points and a second set of distorted calculated points, by applying an image distortion model to said first set of calculated points and to said second set of calculated points, respectively, about a set of auxiliary centers different than said image detector center;
• determining a first set of distances between respective points in said first distorted image and said first set of distorted calculated points;
• determining a second set of distances between respective points in said second distorted image and said second set of distorted calculated points;
• and
• selecting one of said auxiliary centers as said center of distortion, said auxiliary center corresponding to a minimum characteristic value respective of said first set of distances and said second set of distances.

Image distortion correction model for correcting an image distortion in a first distorted image and in a second distorted image of a stereoscopic image pair of an object being detected by an optical device, the image distortion correction model being defined by,

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• wherein x and y are the indices of a current pixel in each of said first distorted image and said second distorted image,
• wherein x0 and y0 define a center of distortion of said first distorted image and of said second distorted image,
• wherein xmax is a distance along said horizontal direction, between a center of a substantially rectangular undistorted calculated image and a side of said substantially rectangular undistorted calculated image, said substantially rectangular undistorted calculated image being respective of said optical device,
• wherein ymax is another distance along said vertical direction, between said center and another side of said substantially rectangular undistorted calculated image,
• wherein parameters a00, a01, a20, a30, a50, a02, a12, a22, a32, a52, c01, c11, c21, c30, c13, c23, c05, c15 and c25 are a set of coefficients which are determined by solving a set of simultaneous Equations for a set of points, each point having the indices x and y, said points being respective of a target being detected by said optical device, the coordinates of said points being known in a global coordinate system,
• wherein fcX(X,Y) designates a horizontal distortion of a point among said points, said horizontal distortion being along said horizontal direction,
• wherein fcY(X,Y) designates a vertical distortion of said point along said vertical direction, and
• wherein x0 and y0 are set to an image center of said substantially rectangular undistorted calculated image.

Method for providing a stereoscopic perception of a scene for a user, such that the vision associated complexions experienced by the user are minimized, the method comprising the procedures of:

• determining a shift between a pair of stereoscopic images to be displayed to said user, said shift being associated with stereoscopic viewing characteristics of said user;
• receiving another pair of stereoscopic images shifted relative to one another by a current shift, said other pair of stereoscopic images being respective of said scene;
• shifting said other pair of stereoscopic images by the difference between said determined shift and said current shift;
• and
• displaying said other pair of shifted stereoscopic images.

Method for varying a local disparity between each depth plane pair of each of a plurality of depth plane pairs, each depth plane of the depth plane pairs defining the depth of a given set of pixels in a first image and a second image of a stereoscopic image pair of an object, relative to an image detector detecting the stereoscopic image pair, the method comprising the procedures of:

• determining a pixel depth for each of said pixels, in said first image and in said second image, from a three-dimensional reconstruction of a volume represented by said stereoscopic image pair;
• determining a plurality of depth planes at a plurality of different plane depths, for said first image and said second image, each of said depth planes being substantially perpendicular to a line of sight respective of a respective one of the eyes of an observer;
• associating each of said depth planes from said first image, with a corresponding depth plane from said second image, at the same plane depth, thereby determining a plurality of depth plane pairs;
• associating each of said pixels with a respective one of said depth plane pairs, according to a respective one of said pixel depths, and according to a respective one of said plane depths;
• and
• varying said local disparity by moving every pair of said depth plane pairs, relative to one another, in a direction substantially perpendicular to said line of sight.