Calculation device, calculation system, calculation method, and calculation program
A trajectory and a flight distance of a target moving body such as a ball hit by a golf club in an athletic competition such as a golf game may be calculated from the images having been taken. The calculation may be conducted from the pictures having been taken with a monocular camera of low resolution such as a smartphone. An initial velocity and a hitting angle of a target moving body such as a ball having been hit high by the golf club may be calculated.
1 . A calculation device of a motion of a target moving body, comprising:
a detecting unit that detects an image of the target moving body from information of each of a plurality of image frames, in which the image of the target moving body is captured, the plurality of image frames being consecutively taken from above with a constant time interval with a monocular camera;
a position calculating unit that calculates a three-dimensional position of the image from a two-dimensional position of the image in the each of the image frames and a three-dimensional position of an optical center of a lens of the monocular camera by approximating the motion of the target moving body as a uniform linear motion;
an initial velocity calculating unit that calculates an initial velocity of the target moving body from the three-dimensional position of the image and the information of the image frames; and
a hitting angle calculating unit that calculates a hitting angle of the target moving body from the three dimensional position of the image and the information of the image frames.
2 . The calculation device according to claim 1 ,
wherein the position calculating unit comprises:
an existence straight line calculating unit that calculates an existence straight line connecting the three-dimensional position of the image and the three-dimensional position of the optical center of the lens; and
an existence surface calculation unit that calculates an existence surface on which the image may exist with a probability,
wherein the position calculating unit calculates, as the three-dimensional position of the image, a three-dimensional position of an intersection of the existence straight line and the existence surface.
3 . The calculation device according to claim 2 ,
wherein the position calculating unit selects a candidate of a three-dimensional position where the image may exist with a highest probability from a plurality of candidates of three-dimensional positions where the image may exist with a probability by a search algorithm and calculates, as a three-dimensional position of the image, the three-dimensional position of the selected candidate.
4 . The calculation device according to claim 3 ,
wherein the position calculating unit searches, through the search algorithm, the candidate of the three-dimensional position where the image may exist with the highest probability by evaluating an evaluation value obtained from a distance between three-dimensional positions where images may exist with probabilities, the images being captured in mutually-neighboring image frames, respectively.
5 . The calculation device according to claim 1 , comprising:
a trajectory calculating unit that calculates a trajectory in three dimensions of the target moving body from the initial velocity of the target moving body and the hitting angle of the target moving body.
6 . The calculation device according to claim 1 , comprising:
a flight distance calculating unit that calculates a flight distance of the target moving body from the initial velocity of the target moving body and the hitting angle of the target moving body.
7 . A calculation system, comprising:
a monocular camera arranged at a position where a target moving body is taken from above with the monocular camera; and
a calculation device as defined in claim 1 .
8 . A calculation method of calculation of a motion of a target moving body, comprising the steps of:
a detecting step of detecting an image of the target moving body from information of each of a plurality of image frames, in which the image of the target moving body is captured, the plurality of image frames being consecutively taken from above with a constant time interval with a monocular camera;
a position calculating step of calculating a three-dimensional position of the image from a two-dimensional position of the image in the each of the image frames and a three-dimensional position of an optical center of a lens of the monocular camera by approximating the motion of the target moving body as a uniform linear motion;
an initial velocity calculating step of calculating an initial velocity of the target moving body from the three-dimensional position of the image and the information of the image frames; and
a hitting angle calculating step of calculating a hitting angle of the target moving body from the three-dimensional position of the image and the information of the image frames.
9 . A calculation device that calculates an initial velocity and a hitting angle of a target moving body, comprising:
a storage device capable of recording information;
an input device capable of inputting information;
a central processing unit capable of calculating based on information;
an output device capable of outputting a calculation result; and
a wired or wireless communication line capable of transferring information to each component thereof;
wherein the central processing unit is operable to:
cause the input device to input information of a plurality of image frames having the target moving body consecutively taken therein from above with a predetermined time interval with a monocular camera and being recorded, the monocular camera being arranged at a position fixed above over an initial position of the target moving body, the target moving body being placed at the initial position when being shot therefrom, and information of the initial position and the position of the monocular camera;
cause the storage device to record the input information;
detect an image of the target moving body in each of the plurality of image frames based on information stored in the storage device;
calculate a three-dimensional position of the image of the target moving body from a two-dimensional position of the image in the each of the plurality of image frames and a three-dimensional position of an optical center of a lens of the monocular camera by approximating a motion of the target moving body as a uniform linear motion based on the information stored in the storage device; and
calculate the initial velocity and the hitting angle of the target moving body from the calculated three-dimensional position of the target moving body.
10 . The calculation device according to claim 9 ,
wherein the central processing unit is operable to:
calculate an existence straight line connecting the three-dimensional position of the optical center of the monocular camera and the three-dimensional position of the image in a real three-dimensional space;
calculate an existence surface on which the image may exist with a probability; and
calculated a three-dimensional position of an intersection of the existence straight line and the existence surface as the three dimensional position of the image.
11 . The calculation device according to claim 9 ,
wherein the central processing unit is operable to:
select a candidate of a three-dimensional position where the image may exist with a highest probability from a plurality of candidates of three-dimensional positions where the image may exist with a probability by a search algorithm; and
calculate the three-dimensional position of the selected candidate as the three-dimensional position of the target moving body.
12 . The calculation device according to claim 11 ,
wherein the central processing unit is operable to:
search, through the search algorithm, the candidate of the three-dimensional position where the image may exist with the highest probability by evaluating an evaluation value obtained from a distance between three-dimensional positions where images may exist with probabilities, the images being captured in mutually-neighboring image frames, respectively.
13 . The calculation device according to claim 9 ,
wherein the central processing unit is operable to:
calculate a trajectory in three dimensions of the target moving body from the initial velocity and the hitting angle of the target moving body.
14 . The calculation device according to claim 9 ,
wherein the central processing unit is operable to:
calculate a flight distance of the target moving body from the initial velocity and the hitting angle of the target moving body.