67 results about "Catadioptric camera" patented technology

A catadioptric camera having a perspective camera and multiple curved mirrors, images the multiple curved mirrors and uses the epsilon constraint to establish a vertical parallax between points in one mirror and their corresponding reflection in another. An ASIFT transform is applied to all the mirror images to establish a collection of corresponding feature points, and edge detection is applied on mirror images to identify edge pixels. A first edge pixel in a first imaged mirror is selected, its 25 nearest feature points are identified, and a rigid transform is applied to them. The rigid transform is fitted to 25 corresponding feature points in a second imaged mirror. The closes edge pixel to the expected location as determined by the fitted rigid transform is identified, and its distance to the vertical parallax is determined. If the distance is not greater than predefined maximum, then it is deemed correlate to the edge pixel in the first imaged mirror.

A catadioptric camera creates images light fields from a 3D scene by creating ray images defined as 2D arrays of ray-structure picture-elements (ray-xels). Each ray-xel capture light intensity, mirror-reflection location, and mirror-incident light ray direction. A 3D image is then rendered from the ray images by combining the corresponding ray-xels.

A paraboloidal catadioptric camera is calibrated by relaxing the assumption of an ideal system to account for perspective projection, radial distortion, and mirror misalignment occurring within the camera system. Calibration points, which are small and visually distinct objects, are distributed at fixed locations within an environment. Omnidirectional images are captured by the catadioptric camera at different locations of the environment. Data points are obtained by identifying the location of the calibration points in each captured image. An optimization algorithm best-fits the data points to a perspective camera model in order to derive parameters, which are used to calibrate the catadioptric camera.

The invention relates to a method of determining intrinsic parameters of a parabolic catadioptric camera through linearity of two mutually-shielded spheres. The method comprises the following steps that five images of a target are shot from different directions by utilizing the parabolic catadioptric camera, parabolic catadioptric images of the target are two intersected quadratic curves, boundary pixel point coordinates and image point coordinates of the five target images are extracted from the images, antipodal image points are obtained according to the relation between the image points and the antipodal image points, curve equations are respectively fitted, two groups of antipodal image points are formed by two actual points of intersection of a sphere image and two actual points of intersection of an antipodal sphere image, through definition of the antipodal image points, the two groups of antipodal image points provide one group of orthogonal direction end points on an image plane, and the intrinsic parameters of the camera are solved by utilizing constraint linearity of the orthogonal direction end points on an absolute conic image. By utilizing the target in the invention, full-automatic calibration can be implemented, and errors caused by measurement in a calibration process are reduced. Projection contour lines of the spheres can be completely extracted in the image, so that the calibration precision of the camera is improved.

The invention relates to a method to solve parabolic catadioptric camera parameters through two intersected straight lines in space. The method is that a target (a calibration object) composed of the two intersected straight lines in the space is used for self-calibration of a parabolic catadioptric camera. Three images of the target are shot by the parabolic catadioptric camera from different directions. A parabolic catadioptric image of a straight line is a quadric curve. Boundary pixel point coordinates and image point coordinates of the three target images are extracted from the images to respectively fit curvilinear equations. Images of disappeared points on image planes along the orthogonal direction are obtained according to that images of harmonic conjugates and two parallel straight lines are intersected to one point. Camera parameters are solved by utilizing the linear constraint of the images on the orthogonal direction on an image of an absolute conic. By utilizing the method, the target can be fully and automatically calibrated, and errors caused by measurement in the calibration process are reduced. Because a straight line is a more concise and more global element, calibration precision of the camera in the calibration process is improved.

The present invention relates to a method for calibration of a parabolic catadioptric camera by employing a ball image and common self-polar triangles. A ball in a space is employed as a calibration object to fit a mirror surface contour projection equation and a ball image equation under a parabolic catadioptric camera and calculate an antipodal ball image equation and an equation of an image ofa great circle having a center of a circle being coincided with a center of a circle of a unit virtual ball and being parallel with a projection small circle of the ball on a unit visual ball model, two common poles, corresponding to two common self-polar triangles formed by the ball image and the antipodal ball image, of the image of the great circle are connected with two common poles to solve avanishing line, a relation of the projection of the circle and the vanishing line is employed to solve the images of circular ring points, and three images are shot to obtain images of the three circular ring points, and the images of the circular ring points and the constraint of the internal parameter matrix of the camera are employed to complete calibration of the camera.

The invention relates to a method to solve parabolic catadioptric camera parameters through one straight line in space. The method is that a calibration object composed of the straight line in the space is used for self-calibration of a parabolic catadioptric camera. Three images of the calibration object are shot by the parabolic catadioptric camera from different directions. A parabolic catadioptric image of a straight line is a quadric curve. Boundary pixel point coordinates and image point coordinates of the three calibration objects images are extracted from the images to respectively fit curvilinear equations. Images of circular ring points on image planes are obtained according to a polarity principle. Camera parameters are solved by utilizing the linear constraint of the images on the circular ring points on an image of an absolute conic. By utilizing the method, the calibration object can be fully and automatically calibrated, and errors caused by measurement in the calibration process are reduced. Because a straight line is a more concise and more global element, calibration precision of the camera in the calibration process is improved.

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 present invention relates to a method for calibrating a parabolic catadioptric camera by using a separate image of double balls and an image of a circular point. An image of double balls used as targets is shot by using the parabolic catadioptric camera, and the targets are separated on an image plane. A main point of an intrinsic parameter of the camera is determined by four groups of imaginary antipodal image points, which are correspondingly formed by imaginary intersection points of ball images in the catadioptric image and imaginary intersection points of antipodal ball images; on the basis of obtaining the main point, vanishing lines of planes where two groups of parallel projection small circles of double balls on a unit virtual ball are positioned are solved, so that the image of the circular point on the plane is determined and finally, other intrinsic parameter of the camera are solved by using the constraint of image of the circular point to the intrinsic parameter of the camera. According to the method provided by the present invention, full automatic calibration can be implemented, and errors caused by measurement in the calibration process are reduced. Since all the projection contour lines of the balls in the image can be extracted, thereby improving the calibration accuracy of the camera.

Camera device and method for shooting light having at least two wavelength bands are disclosed. The camera device includes a first camera containing a first lens for receiving light having a first wavelength band; a second camera including a second lens for receiving light having a second wavelength band which is different from the first wavelength band, the second lens being disposed facing the first lens of the first camera; and a parabolic mirror set between the first camera and the second camera, able to let the light having the first wavelength band penetrate therethrough, and at the same time, reflect the light having the second wavelength band. The first camera is a non-fisheye camera. The first lens is a non-fisheye lens. The second camera and the parabolic mirror form a catadioptric camera. The aperture stop of the non-fisheye lens coincides with the focal point of the parabolic mirror.

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 catadioptric camera of a primer by using a single ball and a parallel circular tangent property, which is characterized in that only the ball element is used; firstly, the edge points of specular contour projection and target image are extracted from three images respectively, and the specular contour projection and spherical image projection areobtained 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; a point on the spherical image is taken and the topological point is found; by defining the topological points and the properties of parallel circles, the above set of topological points provides a vanishing point; in a parabolic catadioptric system, the sphere is projected onto the unit sphere for the first time to form two small parallel circles, two parallel circles on different faces have two pairs of conjugate imaginary intersection points, in which the two conjugate imaginary intersection points which are collinear with the infinity point of the plane in which the circle is located are ring points. Finally, the camera intrinsic parameters are obtained by using the constraint of the image of the torus point to the image of the absolute conic curve.

The invention discloses a method for calibrating the central catadioptric camera through three balls at different spatial positions, and the method is characterized in that the method just employs theball elements. The method comprises the steps: extracting points on an image from a captured ball image, carrying out the fitting of ball images corresponding to the three balls, and solving the pixels corresponding to the centers of small circles formed by the projection of the three balls on a unit virtual globe; solving a polar line of the circle centers relative to the ball images through therelation between a polar point and the polar line; solving two intersection points of the ball images and the polar line, i.e., the images of circle points; obtaining an absolute conic through the images of the obtained six circle points, finally carrying out the decomposition of the absolute conic, and carrying out the inversion to obtain the internal parameters of the camera.

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.

The invention relates to a vehicle (1) comprising at least one catadioptric camera (2), which is mounted on the vehicle and which has an optical axis (5) and at least one first mirror (6) that is arranged on the optical axis. The optical axis (5) of the camera (2) is slanted relative to a vertical (9).

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.