KR-20260064105-A - Camera Parameter Calculation Device, Calculation Method thereof, Program Recording Medium therefor, River Flow Velocity Measurement Device, River Flow Velocity Measurement Method, and Program Recording Medium therefor

KR20260064105AKR 20260064105 AKR20260064105 AKR 20260064105AKR-20260064105-A

Abstract

A camera parameter calculation device capable of further reducing limitations on the subject being photographed, a calculation method thereof, and a program recording medium for the same, as well as a river flow velocity measuring device, a river flow velocity measuring method, and a program recording medium for the same are provided. The camera parameter calculation device of the present invention calculates the parallax between the first and second cameras based on the first and second image regions in which the subject of the first image is overlapped with the subject of the first image, and the first image captured by the second camera so as to overlap with the first image, and calculates the second optical axis direction of the second camera based on the first optical axis direction and the parallax, sets at least two sets of first and second line segments corresponding to each other in the first and second image regions, and calculates the camera parameters of the second camera based on the first height, first optical axis direction, first focal length, and second optical axis direction using the two sets of first and second line segments.

Inventors

하세가와 마코토
정재훈
이민선

Assignees

주식회사 에이치티아이코리아

Dates

Publication Date: 20260507
Application Date: 20241031

Claims (12)

A direction processing unit that calculates the disparity between a first and second camera based on the first and second image regions where the subject overlaps, between a first image captured by a first camera in which a first height from a predetermined reference plane, a first direction of a first optical axis, and a first focal length of a first shooting optical system are known, and a second image captured by a second camera different from the first camera such that at least a part of the subject of the first image overlaps, and calculates the second direction of the second optical axis in the second camera based on the first direction of the first optical axis and the calculated disparity; and A corresponding line segment processing unit that sets at least two sets of first and second line segments corresponding to each other from each of the first and second images in the first and second image regions; and A camera parameter processing unit that obtains camera parameters of a second camera based on a first height, a first direction of a first optical axis, and at least two sets of first and second line segments set in a corresponding line segment processing unit; A camera parameter calculation device including
In claim 1, The above direction processing unit is, A corresponding point search unit that searches for each corresponding point corresponding to each other between the first and second images in the first and second image regions; and A time difference calculation unit that calculates the time difference based on each corresponding point searched by the above-mentioned corresponding point search unit; and, A direction calculation unit that calculates the second direction of the second optical axis toward the second camera based on the first direction of the first optical axis and the parallax calculated by the parallax calculation unit; Includes, or An input unit that receives each corresponding point corresponding to each other between the first and second images in the first and second image regions; and A time difference calculation unit that calculates the time difference based on each corresponding point received from the above input unit; and, A direction calculation unit that calculates the second direction of the second optical axis toward the second camera based on the first direction of the first optical axis and the parallax calculated by the parallax calculation unit; A camera parameter calculation device including
In claim 1, The above-mentioned corresponding line segment processing unit is, A display unit that displays at least one of the first and second images; and An input unit that receives an input line segment from one of the first and second images to one of the first and second line segments; and In the other of the first and second images, an extraction unit that extracts a corresponding line segment corresponding to an input line segment received from an input unit; Includes, or A display unit for displaying first and second images; and, Input unit receiving the first and second line segments; A camera parameter calculation device including
In claim 1, At least two sets of first and second line segments are three or more sets of first and second line segments, and The second camera parameter obtained by the camera parameter processing unit is, in the second camera, a second height from a reference plane and a second focal length of the second shooting optical system, and The camera parameter processing unit calculates the second camera parameter using a calculation formula that calculates the length of the line segment based on the second height and the second focal length, such that the error for each length of at least two sets of first and second line segments is minimized. Camera parameter calculation unit.
A direction processing step for determining the disparity between a first and second camera based on the first and second image regions where the subject overlaps, wherein a first image captured by a first camera having a first height from a predetermined reference plane, a first direction of a first optical axis, and a first focal length of a first shooting optical system, and a second image captured by a second camera different from the first camera such that at least a portion of the subject of the first image overlaps, and determining the second direction of the second optical axis in the second camera based on the first direction of the first optical axis and the determined disparity; and A corresponding line segment processing step of setting at least two sets of first and second line segments corresponding to each other in each of the first and second images in the first and second image regions; and A camera parameter processing step for obtaining camera parameters of a second camera based on a first height, a first direction of a first optical axis, a first focal length of a first imaging optical system, a second direction of a second optical axis obtained in a direction processing step, and at least two sets of first and second line segments set in a corresponding line segment processing step; Camera parameter calculation method.
A computer-readable recording medium having a camera parameter calculation program for enabling a computer to function as a camera parameter calculation device as described in any one of claims 1 to 4.
A camera parameter calculation device described in claim 1; and, A geometric correction unit that generates a plurality of corrected surface images by geometrically correcting each of a plurality of surface images consecutive in a time series captured by a second camera based on camera parameters of the second camera obtained from a camera parameter calculation device; and A flow velocity processing unit that calculates the surface flow velocity on the surface of a river based on a plurality of corrected surface images generated by the geometric correction unit above; A river flow velocity measuring device including
In claim 7, At least two sets of first and second line segments are three or more sets of first and second line segments, including one set of first A and second A line segments set in front of the stream with respect to the second camera, one set of first B and second B line segments set far from the stream with respect to the second camera, and one set of first C and second C line segments set along the width direction of the stream. River flow velocity measuring device.
In claim 7, A flow rate processing unit that calculates the flow rate of a river based on the surface flow velocity obtained by the above-mentioned flow velocity processing unit, the cross-sectional shape of the river, and the water level of the river; River flow velocity measuring device.
In claim 7, First and second cameras; and, A direction measuring unit for measuring the first direction of the first optical axis in the first camera; A river flow velocity measuring device including additional
A method for calculating camera parameters as described in claim 5; and, A geometric correction step of generating a plurality of corrected surface images by geometrically correcting each of a plurality of surface images consecutive in a time series captured by a second camera based on the camera parameters of the second camera obtained by a camera parameter calculation method; and A flow velocity processing step for calculating surface flow velocity at the surface of a river based on multiple corrected surface images generated in a geometric correction step; A method for measuring river flow velocity including
A computer-readable recording medium having a river flow velocity measuring program for making a computer function as a river flow velocity measuring device as described in claim 7.

Description

Camera parameter calculation device, calculation method thereof, and program recording medium therefor, and river flow velocity measurement device, river flow velocity measurement method, and program recording medium therefor The present invention relates to a camera parameter calculation device, a calculation method, and a program recording medium for the same, and to a river flow velocity measuring device, a river flow velocity measuring method, and a program recording medium for the same. When determining a predetermined amount of change regarding an object appearing in an image based on an image captured by a camera, so-called camera parameters are required. These camera parameters generally include, for example, internal parameters such as the focal length and aberration in the camera's imaging optical system (image-forming optical system), and external parameters such as, for example, the direction of the optical axis of the imaging optical system and the position of the camera (the 3D position of the projection center). These camera parameters are generally calculated by arranging six or more reference points with known 3D coordinate values to appear in the image and based on the six or more reference points appearing in the image. In methods using such reference points, time and effort are required to set up the reference points, and since it may be difficult to set up reference points depending on the subject being photographed, it is required to obtain camera parameters without using reference points. An example of such a technique is the camera correction device disclosed in Japanese Patent Document 1. The camera correction device disclosed in the above patent document 1 includes: an acquisition unit that acquires a first normal vector within an image plane and a second normal vector within an image plane, each of which is a normal vector for a reference plane in the world coordinate space captured by the camera and has the same length as a first normal vector within a world coordinate space and a second normal vector within a world coordinate space, respectively; a projection depth calculation unit that calculates a projection depth vector having four projection depths as vector elements, each corresponding to a first starting point and a first ending point of the first normal vector within the image plane and a second starting point and a second ending point of the second normal vector within the image plane, respectively; and a camera parameter calculation unit that calculates internal parameters and external parameters of the camera based on the calculated projection depth vector, a first starting point vector and a first ending point vector within an image plane corresponding to the first starting point and the first ending point, respectively, and a second starting point vector and a second ending point vector within an image plane corresponding to the second starting point and the second ending point, respectively. In this camera correction device, for the normal vectors in the first and second world coordinate spaces, according to paragraph [0016], the edges of buildings or shelves extending perpendicularly to the horizontal plane are used. Figure 1 is a figure illustrating the collinearity condition in camera shooting. FIG. 2 is a flowchart showing the configuration of a river flow velocity measuring device equipped with a camera parameter calculation device according to an embodiment of the present invention. Figure 3 is a diagram illustrating a first type of direction processing unit in the river flow velocity measuring device (camera parameter calculation device) described above. Figure 4 is a diagram illustrating a second type of direction processing unit in the river flow velocity measuring device (camera parameter calculation device) described above. FIG. 5 is a first diagram for explaining the first and second types of corresponding line segment processing units in the river flow velocity measuring device (camera parameter calculation device) described above. FIG. 6 is a second diagram illustrating the first and second types of corresponding line segment processing units in the river flow velocity measuring device (camera parameter calculation device) described above. Figure 7 is a diagram illustrating, as an example, a check line set on an image of a river. Figure 8 is a drawing showing, as an example, an image that has been geometrically corrected from the image shown in Figure 7. Figure 9 is a diagram showing the calculation results of surface flow velocity and water quantity as an example. Figure 10 is a flowchart showing the operation of the river flow velocity measuring device (camera parameter calculation device) described above. One or more embodiments of the present invention are described below with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. Meanwhile, components given the same reference numeral in each dra