60results about How to "Physical scale is not required" patented technology

The invention relates to a method for solving camera intrinsic parameter by using the image of the center of a sphere and orthogonality. The method comprises: firstly, taking three pictures of a calibrated sphere from different directions and reading the images, extracting coordinates of three quadratic curves from the three images; according to imaging process of the sphere and the center of the sphere under the camera, solving to obtain image coordinates of three centers of spheres, and according to projections of the centers of spheres, calculating end points on orthogonal directions, and finally by using the end points on orthogonal directions, solving images of absolute conics, and according to the images of quadratic curves, and solving a constraint matrix of camera intrinsic parameters, so as to obtain the camera intrinsic parameter. By using the spheres which are targets, full-automatic calibration can be realized, and errors caused by measurement in a calibration process are reduced. Since the quadratic curve is a simpler and more global element, and projection contours of the spheres can be completely extracted from the images, calibration precision is improved in a camera calibration process.

The invention relates to a method for marking intrinsic parameters of a camera by solving an image of a circular point, wherein the image of the circular point is solved by solving a plane vanishing line by using any three non-concentric circles on a plane and by using centers of the three non-concentric circles. According to the method for solving the intrinsic parameters of the camera by using the three non-concentric circles, three images are shot in different directions by a target, image curves of the three circles on each image and coordinates of the images of each three centers are extracted, a homogeneous coordinate of the plane vanishing line is obtained by using relation of a pole and a polarline formed by the centers and the vanishing line according to the theory of the pole and the polarline and through solving three simple linear equations, the image of the circular point is solved by solving an intersection point between the vanishing line and the image of any of the three circles, and then the five intrinsic parameters of the camera is determined by building a constraint equation about the intrinsic parameters of the camera by using the image of the circular point. Due to the fact that a curve of the second degree is a simple and an overall element, solving the vanishing line by fitting the curve of the second degree is higher in stability than solving the vanishing line by fitting a point and a plane. The method for solving the intrinsic parameters of the camera by using the three non-concentric circles is high in application value.

The invention relates to a method for linearly solving camera inner parameters by using two identical intersected ellipses. According to the method, a target drone which is formed by two identical intersected ellipses sharing the same main axis and which is calibrated by a camera is adopted; five images of the target drone are shot in different directions; an ellipse equation is extracted from the images and the intersection points of the two ellipse are solved; end points in the planes of the images in the orthogonal directions are obtained according to the polarity principle and the property of the cross ration of four straight lines; and camera inner parameters are linearly solved by using the end points in the orthogonal directions and the constraint of the images of absolute conics. With the adoption of the target drone in the method, the full-automatic calibration can be implemented, the error caused by the measurement in the calibration process is reduced, and the calibration precision in the calibration process of the camera is improved as the conic is a simpler and more global-oriented element.

A method for calibrating a parabolic refraction and reflection camera via single ball and parallel circle properties is disclosed. In a parabolic refraction and reflection system, two small parallel circles are formed when a ball is projected onto a unit visual ball for a first time. The two parallel circles in a space have two pairs of conjugated virtual intersection points, and two conjugated virtual intersection points that are collinear with a point at infinity on a plane where space circles are positioned are circular ring points. An image of the circular ring points is obtained on an image plane according to colinearity of the image of the circular ring points and a vanishing point; three images provide images of three groups of circular ring points. Intrinsic parameters of the camera are solved via constraints posed on an absolute conic image by the images of the circular ring points. The method specifically comprises the following steps: a mirror surface contour projection equation and a target projection equation are fitted, an antipodal sphere image of a sphere image is estimated, the images of the circular ring points are determined, and the intrinsic parameters of the parabolic refraction and reflection camera are solved.

The invention relates to a method for calibrating a parabolic refraction and reflection camera through the Veronese mapping and a checkerboard. The method is characterized in that the target of the method is formed by a known checkerboard in the space. The method comprises the specific steps of during the solving process of the internal parameters of a parabolic refraction and reflection camera, shooting 3 images by the parabolic refraction and reflection camera; obtaining three homography matrixes through the Veronese mapping so as to solve a vanishing point for any straight line; solving another vanishing point based on the relationship between antipodal points and harmonic conjugates, wherein the connecting line of the two vanishing points is a vanishing line; according to the intersection points of the vanishing line with the image of the straight line namely a quadratic curve, solving the image of three sets of circular points; based on the constraint of the image of circular points on the image of the absolute quadratic curve, solving the internal parameters of the parabolic refraction and reflection camera through the Cholesky decomposition.

The invention relates to a method for linearly solving parameters in a parabolic catadioptric camera through three unparallel straight lines in a checkerboard. The method is characterized in that only linear elements are utilized, and a template is composed of the three unparallel straight lines on the checkerboard; parabolic catadioptric images of the straight lines are quadratic curves, the parabolic catadioptric camera is used for taking an image of a target, image points of the target are extracted from the image first, fitting is conducted to obtain the curve equation, and the intersection points of every two curves are solved, six sets of orthogonal fading points on the image plane are then obtained according to the geometric properties of a circle and the cross ratio invariance property, and the parameters in the parabolic catadioptric camera are linearly solved for constraints on images of the absolute quadratic curves through the orthogonal fading points. According to the method, the target can be calibrated in a full-automatic mode, and errors caused by measurement in the calibration process are reduced. Due to the fact that the straight lines are the simpler and more comprehensive elements, calibration accuracy is improved in the calibration process of the camera.

The invention relates to a method for calibrating a camera by means of solving images of two vanishing points in orthogonal directions or images of circular points by the aid of two concentric circles on a plane and two points which are positioned on one of the circles but are not positioned on the same diameter. The method includes that three images for a target are taken from different directions, and coordinates of a curve and coordinates of two points on each image are extracted; points, which correspond to an image of a circle center and images of two points relative to the circle center, on each curve are computed, and the two vanishing points in the orthogonal directions are acquired from intersection points of straight lines; and a vanishing line on each image can be acquired by implementing a theory of dual quadratic curves of the circular points, the images of the circular points are intersection points of images of the vanishing lines and the circles, constraint equations of the images of the vanishing points in the orthogonal directions or the images of the circular points relative to intrinsic parameters of the camera are established, and the five intrinsic parameters of the camera can be linearly solved. The method has the advantages that full-automatic calibration can be realized owing to the target, errors caused by measurement in a calibration procedure are reduced; and the quadratic curves are concise and comprehensive elements, and accordingly the precision is improved in the calibration procedure.

The invention relates to a target for determining camera intrinsic parameters. The target is characterized in that the target is composed of at least three centers of any non-concentric circles in a plane, and the specific steps comprises estimating coordinates of images of the centers of the circles, and estimating vanishing line of the images in the plane by utilizing polarity principle to realize a linear method for camera intrinsic parameters. According to the target for determining the camera intrinsic parameters, three images are taken for the target from different directions, curvilinear equation for each image is extracted, the images of the centers of the circles and equations of the vanishing line on the images are figured out, intersections between the vanishing line and the images of the circles are images of ring points, constraint equations for the images of the ring points, which is related to the camera intrinsic parameters, are established, and matrix for the camera intrinsic parameters of is linearly solved. The target disclosed in the invention can be utilized to realize full-automatic calibration, so that errors caused by measurement in the calibration process are reduced. A quadratic curve is a more simple and globalized element, thereby improving the precision in the calibration process.

A method for calibrating a catadioptric camera by using the property of an infinitely distant point with respect to a circular pole line is characterized in that a ball in space is used as a target. The method comprises the following steps of firstly extracting edge points of a target image and edge points of a mirror contour projection of one image from three images respectively; secondly, according to the relation between the image point and its extension point, obtaining the extension point, and then fitting the extension spherical image of the spherical image; taking two different points on the spherical image and obtaining the opposite extension points of the two points; according to the definition of topological points and the properties of circles, using the two sets of topologicalpoints to provide a vanishing point; taking two dissimilar points from the spherical image, and obtaining two vanishing points. Wherein the straight line of the two vanishing points is the vanishing line; finally, obtaining the camera intrinsic parameters by using the constraint of the orthogonal vanishing point to the absolute conic image.

The invention relates to a method for calibrating a parabolic refraction-reflection camera via an intersection image of two spheres and images of circular ring points. The parabolic refraction-reflection camera shoots a target to obtain one image, a main point is determined via four groups of antipodal image points corresponding to solid and virtual intersection points in a spherical image in the refraction-reflection image and solid and virtual intersection points of an antipodal spherical image, a disappearance line of a plane, where two small parallel projection circles are placed in a unit visual sphere, of the two spheres is solved, images of the circular ring points in the plane are determined, and finally, the circular ring points are used to solve other inner parameters of the camera according to limitations of the inner parameters. The method of the invention can be used to realize full-automatic calibration, and reduce errors caused by measurement in the calibration process. Due to the fact that the projection contours of the spheres can be completely extracted from the images, the calibration precision of the camera is improved.

The invention relates to a method for calibrating a pinhole camera by using a public autopolar triangle and an orthogonal vanishing point of a separation circle. Firstly, edge points of a target imageare extracted from the image, and a circular image equation is obtained through least square method fitting. According to the fact that any two separated circular images have a unique public self-polar triangle, a group of corresponding poles and polar lines of the pair of separated circular images can be obtained. Meanwhile, the polar line is an image passing through the circle centers of the two circles, and the polar point is a vanishing point. Wherein the vanishing point has a polar line relative to the separated circle image, the polar line passes through the image of the circle center and the circle image and is intersected with the two points, the image of the circle center and the vanishing point in the polar line direction can be obtained by utilizing the property of harmonizingand conjugating the two intersected points and the image of the circle center, and the obtained two vanishing points are a group of orthogonal vanishing points. Therefore, six groups of orthogonal vanishing points can be obtained from the six images, and the internal parameters of the pinhole camera are solved by using the constraint of the orthogonal vanishing points and the image of the absolutequadratic curve.

The present invention relates to a method of utilizing a projection matrix of a Veronese mapping checkerboard to calibrate a central catadioptric camera. The method comprises the steps of using the central catadioptric camera to shoot a target image, and extracting the image points corresponding to the checkerboard in the space; utilizing the Veronese mapping to expand the coordinates, and using a DLT-similarity method to estimate the projection matrix linearly; utilizing the projection matrix to solve the parameters in the camera. By utilizing the method of the present invention, no physical scale requirement is required, the points are easy to select, the point sources are abundant, the calibration errors caused by the data errors during a calibration process are reduced, and the one-to-one correspondence of the image points and the angular points of the space checkerboard can be controlled, thereby improving the calibration precision of the camera.

The invention relates to a method for calibrating a camera by means of solving two vanishing points in orthogonal directions by the aid of three externally or internally tangent circles on a plane. The method includes that three images are taken for a target from different directions, equations of various curves on the images and coordinates of tangent points of the images are extracted, projection coordinates of centers of the various circles are solved, a corresponding point of an image of each tangent point relative to an image of each circle center on a projection curve and a tangent line of the image of the tangent point and the corresponding point relative to the projection curve are solved, and the two vanishing points in the orthogonal directions are solved according to a principle of cross-ratio invariance and intersection points of the tangent lines; and the two vanishing points in the two orthogonal directions on the three images are computed, constraint equations of intrinsic parameters of the camera are established, and the five intrinsic parameters of the camera are linearly solved. The method has the advantages that full-automatic calibration can be realized owing to the target, and errors caused by measurement in a calibration procedure are reduced; and as the quadratic curves are concise and comprehensive elements, the calibration precision is improved in the camera calibration procedure.

The present invention relates to a method for calibrating a parabolic catadioptric camera by using a separated two-ball image and an orthogonal vanishing point. The method comprises: firstly, using the parabolic catadioptric camera to shoot an image of a target, wherein the target is two balls with separated projections on an image plane; obtaining an antipodal image point according to a relationship between an image point and the antipodal image point of the image point, thereby estimating an antipodal ball image of the two-ball image in a catadioptric image, and solving intersection points of the two-ball image and intersection points of the antipodal ball image of the two-ball image; secondly, determining the orthogonal vanishing point according to four groups of virtual antipodal image points correspondingly formed by virtual intersection points of the ball image and the antipodal ball image; and finally, solving an intrinsic parameter of the parabolic catadioptric camera by using constraint of the orthogonal vanishing point on the intrinsic parameter of the camera.

Provided is a method for calibrating a parabolic type catadioptric camera by using a straight line and a circular point image, and the method is characterized in that a straight line in the space is taken as a target. The method includes firstly shooting three straight-line-containing images from different positions by means of the parabolic type catadioptric camera, extracting the edge point of the mirror surface contour projection and the edge point of the target image, and obtaining a mirror surface contour projection and a straight line image by means of the least square fitting; taking one point on the line image, and obtaining an antipodal image point, wherein the intersection point of the image point and the antipodal image point relative to the tangent line of the line image is a vanishing point; taking two different points from the line image to obtain two vanishing points; determining one vanishing line with the two vanishing points, wherein the intersection point of the vanishing line and the line image is the image of the circular point, and three images provide three groups of images of the circular point; and finally, solving the internal parameters of the camera through the constraint of the images of the circular point on the absolute quadratic curve image.

The invention relates to a method for solving camera inner parameters by using a dot matrix template and orthogonality. The method comprises the following steps: firstly, taking out a physical coordinate of a dot matrix in a template; extracting a matching point in an image; estimating a homography matrix between the image and the template; supposing the slopes of two non-parallel and non-orthogonal straight lines in a template plane; calculating to obtain the slope of a straight slope orthogonal with the straight lines in the template plane; further calculating a coordinate of an in infinite point of the two groups of orthogonal straight lines; obtaining orthogonal end points through perspective projection transformation; shooting at least three images according to the relationship of the orthogonal end points and an absolute conic image so as to linearly solve the camera inner parameters. With the adoption of the template in the method, the full-automatic calibration can be implemented, and the measurement error in the calibration process is reduced.

The invention relates to a method for calibrating a catadioptric camera of a primer by using properties of a single ball and a midpoint of a chord. Firstly, the edge points of the specular contour projection and the target image are extracted from the image, and the specular contour projection and the spherical image projection are obtained by least square fitting. Secondly, according to the relationship between the image point and its extension point, the extension point is obtained, and then the extension spherical image of the spherical image is fitted. Two different points are taken from the spherical image, and the two points' topological points are obtained. From the definition of topological points and the properties of circles, the two sets of pairs of topological points can determine the midpoint of the upper chord of the sphere image. The image of the center of a circle is determined according to the properties of the two points on the spherical image with respect to the polar line of the spherical image and the midpoint of the chord. The polar line of the center of a circle with respect to the spherical image is the shadow cancellation line, and the intersection point ofthe shadow cancellation line and the spherical image is the image of a circular ring point. Three images provide three sets of images of circular ring points. Finally, the camera intrinsic parametersare obtained by using the constraint of the image of the torus point to the image of the absolute conic curve.