JPH0886851A - Image target distance measuring apparatus - Google Patents

Abstract

PURPOSE: To obtain an image target distance measuring apparatus which is loaded onto an airplane, by which the distance between a target such as a fleet or the like and the airplane is measured and by which a distance measuring error can be corrected. CONSTITUTION: A part in which a temperature becomes highest on a target is measured by an infrared camera 14a, an image processing part 7 and a high- temperature position detection part 8a. It is used as a distance measuring point. In a distance computation part 11a, altitude data by an altimeter 6 is corrected by using altitude data on a target high-temperature part in a target data storage part 10a. The distance between an airplane and the target is computed on the basis of angle information on the distance measuring point and on the basis of a corrected altitude.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image target distance measuring device mounted on an aircraft for measuring a distance to a target such as a ship.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram of a conventional aircraft image target range finder. In the figure, 1b is an optical system for converging and forming a target within a field of view, and 2b is an optical system 1b for converging and converging. An image pickup unit 3 for converting the formed optical image into an image signal, a gimbal unit 3 for moving the visual axis of the camera 14b including the optical system 1b and the image pickup unit 2b, and 4 for controlling the visual axis orientation to detect the angle of the visual axis. Gimbal control / visual axis angle detection unit, 5 is an inertial navigation device that detects the attitude angle, velocity, and acceleration with respect to the inertial reference coordinate system of the aircraft that has the camera 14b, and 6 is the altitude of the aircraft that has the camera 14b. An altimeter for detecting the position, 7 is an image processing unit for binarizing an image signal obtained from the image pickup unit 2b, and extracting a target, and 15 is a barycentric position calculation for calculating a barycentric point of the target image extracted by the image processing unit 7. Part 9 is the inertial group of the extracted target A target angle calculation unit that calculates the angle of the coordinate system, 11c is a distance calculation unit that calculates the distance between the aircraft and the target from the angle of the target and the altitude of the aircraft, 12 is a display unit that displays the calculated distance, and 13 is gimbal control. An operation unit for inputting an angle command for operating the visual axis to the visual axis angle detection unit 4.

Next, the operation will be described with reference to FIG. The optical image formed by the optical system 1b is output as an image signal by the imaging unit 2b. Here, the operator sends an angle command to the gimbal control / visual axis angle detection unit 4 by the operation unit 13 in order to visually detect the target and direct the visual axis in the target direction in which the distance measurement is desired. The gimbal unit 3 directs the visual axis toward the target direction by an angle control signal from the gimbal control / visual axis angle detection unit 4. The image processing unit 7 binarizes the image signal obtained from the image pickup unit 2b using a threshold value with the target background level as a reference, and extracts it as a target. The center-of-gravity position calculation unit 15 calculates the center-of-gravity point of the extracted target image and sets it as the distance measuring point. The position of the center of gravity in the inertial coordinate system is calculated by the target angle calculator 9 as an angle in the inertial coordinate system from the angle difference between the pixel of the target center of gravity and the visual axis and the attitude angle of the aircraft. In the distance calculation unit 11c, the distance between the aircraft and the target is calculated from the target angle information and the altitude detected by the altimeter 6 according to "Equation 1" or "Equation 2". "Equation 1" is a calculation formula that considers the roundness of the earth, and "Formula 2" is a calculation formula when the roundness of the earth is ignored. The calculated distance is displayed on the display unit 12 and is clearly shown to the operator.

[0004]

[Equation 1]

[0005]

[Equation 2]

FIG. 11 is a diagram showing distance measurement for a ship at sea. The distance measured with respect to the distance R2 between the aircraft and the ship is R1, and the distance measurement error R3 occurs due to the height H2 of the target center of gravity, which is the distance measurement center, from the sea surface.

12 and 13 are views for explaining the coordinate system. In FIG. 12, the coordinates (XA, YA, ZA) are the origin of the mounting position of the inertial navigation device and the axis of the aircraft is the axis XA.
The airframe reference coordinate system in which the vertical direction of the aircraft is the axis ZA and the orthogonal axes are the axes YA is shown. Coordinates (XO, Y
O, ZO) has an origin at the mounting position of the inertial navigation device 5, the gravity direction is an axis ZO, and north-south direction and east-west direction are respectively axes X.
O indicates the inertial reference coordinate system with the axis YO, and the coordinates (X
C, YC, ZC) is a reference coordinate system of the camera which indicates the direction of the visual axis of the camera and is parallel to the aircraft reference coordinate system. The inertial navigation device 5 uses the aircraft reference coordinate system with respect to the inertial reference coordinate system as the attitude angle of the aircraft. The roll angle, pitch angle, and yaw angle that are the rotation angles are detected. In FIG. 13, the angular coordinates (AZt, ELt) of the target center-of-gravity point represented by the azimuth angle and the elevation angle with the visual axis as the origin are changed from the reference coordinate system of the camera to the inertial reference coordinate system using the attitude angle of the airframe. Angular coordinates (AZo, E
The coordinates are converted into Lo). The target elevation angle ELo in this inertial reference coordinate system is the same as the angle θ of “Equation 1” and “Equation 2” and is used for distance calculation.

[0008]

Since the conventional image target range finder is constructed as described above, the range height error occurs because the height of the target becomes an altitude error, and in particular, the altitude of the aircraft is low. There was a problem that it had a great influence in some cases.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image target distance measuring device capable of correcting a distance measuring error caused by the height of a target such as a ship.

[0010]

An image target distance measuring apparatus according to the present invention comprises a specific part detecting means for detecting a specific part in an extracted target image, and an altitude of the target specific part detected by the specific part detecting means. The data storage means stores height data from the zero reference plane of the detection means, and the distance calculation means for correcting the calculated distance based on the height data of the target specific portion.

Further, the present invention is an infrared camera comprising an infrared optical system and an infrared imaging section, a high temperature position detecting section for detecting a high temperature section of a target, and a target data storing section for storing height data of the high temperature section of the target. Section and a distance calculation section that calculates a distance using height data of a target high temperature section.

The present invention uses a barycentric position detecting section for detecting a barycentric point of a target image, a target data storing section for storing height data of the barycentric point of the target, and height data of the barycentric point of the target. And a distance calculation unit that calculates the distance.

Further, according to the present invention, a target dimension calculating unit for estimating a target dimension from a distance obtained by calculating the extracted target pixel number, and target data storage for storing height data of a target specific portion and target dimension data are stored. And a distance calculation unit that calculates a distance using height data of the estimated target dimension and the target obtained from the data of the target data storage unit.

According to the present invention, the target data storage unit classifies the data according to the number of specific parts in the target detected by the specific part detecting means, and the target data from the number of specific parts in the target image detected by the specific part detecting means. It is composed of a target determination unit that selects a target of the storage unit.

Further, the present invention is provided with a lowest point detecting section which uses the lowest point of the extracted target image as a distance measuring point.

[0016]

In the present invention, a specific area in the extracted target image is detected as a distance measuring point, and the calculated distance is corrected by the height data of the target at the distance measuring point to correct the distance measuring error due to the height of the target. To reduce.

Further, the high temperature portion of the target image is imaged by an infrared camera having a high brightness level, the target high temperature portion is detected and used as a distance measuring point, and the distance calculated by the height data of the target high temperature portion held. The distance measurement error due to the height of the target is reduced by correcting

By detecting the center of gravity of the target as a distance measuring point and correcting the calculated distance by the height data of the center of gravity of the target which is held, the distance measuring error due to the height of the target is reduced.

Further, the target dimension is estimated from the extracted target pixel number and the calculated distance, and the height data corresponding to the target dimension estimated from the height data of the target specific portion and the target dimension data stored in advance is obtained. Then, the height data is fed back and the distance is sequentially recalculated to correct the distance measurement error using the optimum height data from the plurality of target data.

By detecting a plurality of high temperature parts from the target image taken by the infrared camera and selecting suitable data from the data classified by the number of high temperature parts, the optimum height data is used from the plurality of target data. Correct the distance measurement error.

Further, by setting the lowest point of the extracted target image as the distance measuring point, the distance measuring error due to the height of the target is reduced.

[0022]

【Example】

Example 1. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 3, 4, 5, 6, 7, 9, 1
2 and 13 are the same as the conventional device. Reference numeral 1a is an infrared optical system for focusing and forming infrared rays, and 2a is an infrared optical system 1.
An infrared imaging unit that converts the optical image focused and formed by a into an image signal, 14a is an infrared camera, 8a is a high temperature position detection unit that detects a high temperature portion in the target from the extracted target image, and 10a is a high temperature of the target. Is a target data storage unit that stores height data from the zero reference plane of the altimeter 6 of the section,
The altimeter zero reference plane is the water surface if the target is a ship. Reference numeral 11a is a distance calculation unit that corrects the altitude data of the altimeter 6 based on the target height data and calculates the distance.

Next, the operation of FIG. 1 will be described. The optical image formed by the infrared optical system 1a is an infrared imaging unit 2a.
Is output as an image signal. High temperature position detector 8a
At, the pixel having the maximum image brightness level in the target image extracted by the image processing unit 7 is specified and the high temperature portion is detected. When the target is a ship, the hottest part is the tip of the chimney, and the pixel that becomes the distance measuring point by the infrared camera 14a is the chimney position. The position of the focus point in the inertial coordinate system is
The target angle calculation unit 9 calculates the angle of the inertial coordinate system from the angle difference between the pixel at the distance measuring point and the visual axis and the attitude angle of the aircraft. In the distance calculation unit 11a, the altitude data obtained by the altimeter 6 is corrected by "Equation 3" using the height data from the draft to the chimney of the target data storage unit 10a, and is calculated from the angle information of the pixel at the distance measuring point and the corrected altitude. "Number 1" or "Number 2"
Calculates the distance between the aircraft and the target.

[0024]

(Equation 3)

FIG. 2 shows an example of distance measurement according to the first embodiment.
The distance measurement error R3 can be eliminated by calculating the distance R2 based on the altitude difference between the aircraft and the chimney.

Example 2. FIG. 3 is a block diagram showing another embodiment of the present invention, which is 1a, 2a, 3, 4, 5, 6,
7, 9, 11a, 12, 13, and 14a are the same as those in the first embodiment, and 15 is the same center-of-gravity point position calculation unit as in the related art. Reference numeral 10b denotes a target data storage unit that stores height data from the zero reference plane of the altimeter 6 of the target center of gravity,
The altimeter zero reference plane is the water surface if the target is a ship. Here, 14a is not the infrared camera but the conventional camera 1
It may be 4b.

Next, the operation of FIG. 3 will be described. The target image extracted by the image processing unit 7 is the center of gravity position calculation unit 15.
The center-of-gravity point is calculated and becomes the distance measuring point. When the target is a ship, the distance calculation unit 11a uses the height data from the draft of the center of gravity calculated by making the density of the hull volume above the draft stored in the target data storage unit 10b uniform, The altitude is corrected by "3", the distance between the aircraft and the target is calculated by "Equation 1" or "Equation 2" from the angle information of the distance measuring point and the corrected altitude, and the target is calculated by the height data of the target center of gravity point. Distance measurement error due to the height of can be reduced. FIG. 4 shows an example of distance measurement. The distance measurement error R3 can be eliminated by calculating the distance R2 by the altitude difference between the center of gravity of the aircraft and the center of gravity of the ship.

Example 3. FIG. 5 is a block diagram showing another embodiment of the present invention, which is 1a, 2a, 3, 4, 5, 6,
7, 8a, 9, 12, and 13 are the same as those in the first embodiment. Reference numeral 10c is a target data storage unit that prestores target data including height data from the zero reference surface of the altimeter 6 of the target high temperature portion and target length data, and 11b is the altitude of the altimeter 6 based on the target height data. A distance calculator that corrects data, calculates a distance, and feeds back the calculated distance.
Is a target dimension calculation unit that calculates the target length from the target number of pixels and the distance. If the target is a ship, the zero reference plane of the altimeter 6 is the water surface, and the length data indicating the size of the ship and the height data of the chimney part, which is the high temperature part of the target, correspond in a one-to-one correspondence. Remembered in.

Next, the operation of FIG. 5 will be described. The target dimension calculation unit 16 calculates the target length from the distance from the distance calculation unit 11b and the target number of pixels from the image processing unit 7 according to "Equation 4". The height data of the target high temperature portion 8a corresponding to the calculated target length is output from the target data storage unit 10c to the distance calculation unit 11b. In the distance calculation unit 11b, the altitude is corrected by "Equation 3" using the output height data, and the aircraft and the target are determined by "Equation 1" or "Equation 2" from the angle information of the distance measuring point and the corrected altitude. The optimum height data is used by repeatedly calculating the distance between and and displaying the distance on the display unit 12 when the difference between the previous calculated distance and the new calculated distance is within the set range. The distance measurement error can be corrected.

[0030]

[Equation 4]

FIG. 6 shows a target data storage unit 1 according to the third embodiment.
It is a figure explaining the repeated calculation by 0c and the distance calculation part 11b. If the target is a ship, the target data storage unit 10c
The height data of the chimney portion with respect to the length of the ship is stored in. As the initial value, the stack height is 0 [m] and the distance is R
O is calculated, and the length of the ship obtained from the distance is L1. The height data h1 of the chimney portion corresponding to the length L1 is obtained from the target data storage unit 10c, and the distance R2 is calculated by the distance calculation unit. The target dimension calculator calculates the length L2 of the ship using the distance R2 and repeats. N in the distance calculation unit 11b
If the difference between the distance RN for the first time and the distance RN-1 for the (N-1) th time falls within the set range, the iterative calculation of the distance calculation ends.

Example 4. FIG. 7 is a block diagram showing another embodiment of the present invention, which is 1a to 7, 9, 11b, 12, 1.
3, 14a and 16 are the same as those in the third embodiment. 8b
Is a high-temperature position detection unit capable of detecting a plurality of high-temperature parts in the target from the extracted target image, and 10c is height data from the zero reference plane of the altimeter 6 of the target high-temperature part classified by the number of target high-temperature parts and the target data. A target data storage unit for storing length data in advance, 17 is a target discriminating unit for discriminating the target data according to the number of high temperature portions detected by the high temperature position detecting unit 8b. When the target is a ship, the zero reference plane of the altimeter 6 is the water surface, and it is possible to divide the types of ships having different length data and height data depending on the number of chimneys that are high temperature parts.

Next, the operation of FIG. 7 will be described. The high-temperature position detecting unit 8b detects a high-temperature portion by extracting a portion exceeding a threshold value set based on the maximum brightness level in the target image extracted by the image processing unit 7. When the target is a ship, in the case of a ship having two chimneys, the number of high temperature parts detected by the high temperature position detecting part 8b is two. The target determination unit 17 supplies the target data storage unit 10c with the number data of high temperature parts, and the target data storage unit 10c selects the target length and height data divided by the number of chimneys, and the same as in the third embodiment. By correcting the altitude from the target height data and calculating the distance, the distance measurement error can be corrected using the optimum height data from the target data storage unit.

Example 5. FIG. 8 is a block diagram showing another embodiment of the present invention. 1a, 2a, 3, 4, 5, 6,
7, 9, 11a, 12, 13, 14a and 15 are the second embodiment
The reference numeral 18 denotes the lowest point detection unit for detecting the pixel at the lowest point in the inertial coordinates of the extracted target image.
Here, 14a is not an infrared camera but a conventional camera 14b.
But it is okay.

The operation of FIG. 8 will be described. The lowest point detection unit 18 transforms the extracted target pixel into an inertial coordinate system, finds the pixel that is the lowest point on the elevation angle of the inertial coordinate system from the target center of gravity point obtained by the center of gravity position calculation unit 15, and measures the distance. It is a point. The elevation angle of the distance measuring point in the inertia reference coordinate system is obtained by the target angle calculation unit 9, and the distance calculation unit 11c calculates the distance using the altitude data. When the target is a ship, the distance-measuring point obtained is the intersection of the line extending vertically from the center of gravity and the waterline, and distance measurement can be performed without the error of the target height.
Figure 9 shows the lowest point of the target ship on the imaging screen, which is the focus detection point.
It is a figure showing distance measurement to the lowest point.

[0036]

As described above, in the image target distance measuring device according to the present invention, a specific portion in the extracted target image is detected as a distance measuring point, and the distance calculated by the target height data of the distance measuring point is calculated. It is possible to reduce the distance measurement error due to the height of the target by correcting.

Further, the high temperature portion of the target image is imaged by an infrared camera having a high brightness level, the high temperature portion of the target is detected and used as a distance measuring point, and the distance calculated by the height data of the high temperature portion of the target held. By correcting the distance, the distance measurement error due to the target height when measuring the distance of a ship or the like is reduced.

Further, even if the target does not have a high temperature portion, the height of the target can be corrected by detecting the center of gravity of the target as a distance measuring point and correcting the calculated distance based on the height data of the center of gravity of the target held. It is possible to reduce the distance measurement error due to.

Further, the target dimension is estimated from the extracted target pixel number and the calculated distance, and the height data of the target specific portion and the height data obtained from the database of the target dimension data are fed back to successively recalculate the distance. By calculating, the distance measurement error can be corrected by using the optimum height data from the database having a plurality of target data.

Further, by detecting a plurality of high temperature parts from the target image picked up by the infrared camera and selecting suitable data from the database classified by the number of high temperature parts,
The distance measurement error can be corrected using the optimum height data from the database having a plurality of target data.

Further, by setting the lowest point of the extracted target image as the distance measuring point, the distance measuring error due to the height of the target can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an image target distance measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of distance measurement of the image target distance measuring device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing an image target distance measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing an example of distance measurement of an image target distance measuring device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing an image target distance measuring device according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a repetitive calculation according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing an image target distance measuring device according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing an image target distance measuring device according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing an example of distance measurement of an image target distance measuring device according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a conventional image target distance measuring device.

FIG. 11 is a diagram showing an example of distance measurement of a conventional image target distance measuring device.

FIG. 12 is a diagram showing a coordinate system of an aircraft.

FIG. 13 is a diagram showing the relationship between the coordinate system of the image target distance measuring device and the inertia reference coordinate system.

[Explanation of symbols]

1a infrared optical system, 1b optical system, 2a infrared imaging section, 2b imaging section, 3 gimbal section, 4 gimbal control
Visual axis angle detector, 5 inertial navigation system, 6 altimeter, 7
Image processing unit, 8a high temperature position detection unit, 8b high temperature position detection unit, 9 target angle calculation unit, 10a target data storage unit, 10b target data storage unit, 10c target data storage unit, 11a distance calculation unit, 11b distance calculation unit, 11c
Distance calculation unit, 12 display unit, 13 operation unit, 14a
Infrared camera, 14b camera, 15 barycentric position calculating unit, 16 target dimension calculating unit, 17 target determining unit, 18
Lowest point detector, 19 camera visual axis, 20 roll angle,
21 yaw angle, 22 pitch angle, 23 aircraft, 24
origin.

Claims (6)

[Claims] 1. An image pickup means, an image processing means for extracting a target from an image obtained from an image pickup section of the image pickup means, and an inertia for detecting an attitude angle of an aircraft equipped with the image pickup means with respect to an inertial reference coordinate system. Navigation device, altitude detecting means for detecting the altitude of an aircraft equipped with the image capturing means, target angle calculating means for calculating the angle of the target inertial reference coordinate system extracted by the image processing means, and target angle In the image target range finder including a distance calculating means for calculating the distance between the aircraft and the target from the altitude of the aircraft and a display means for displaying the calculated distance, identification in the target image extracted by the image processing means is specified. Data storage for storing height data from the zero reference plane of the altitude detection means of the target specific portion detected by the specific portion detection means An image target distance measuring device comprising: means and distance calculating means for correcting the calculated distance based on the height data of the target specific portion. 2. An image pickup unit including an infrared optical system and an infrared image pickup unit, a specific portion detection unit including a high temperature position detection unit that detects a high temperature portion in the target from the extracted target image pickup, and a height of the target high temperature portion. Data storage unit that stores a target data storage unit in advance, and a distance calculation unit that includes a distance calculation unit that calculates a distance using the target height data of the high temperature portion. The image target distance measuring device according to claim 1. 3. A specific part detecting means comprising a barycentric position detecting section for detecting a barycentric point of the extracted target image, and a data storing means comprising a target data storing section for storing height data of the target barycentric point. The image target distance measuring apparatus according to claim 1, wherein the image target distance measuring apparatus comprises a distance calculating unit including a distance calculating unit that calculates a distance using height data of a target center of gravity point. 4. A target size calculation unit that estimates a target size from the number of pixels of the extracted target image and the calculated distance, height data of a target specific portion, and target size data corresponding to the height data are stored in advance. And a distance calculation unit that calculates a distance using the estimated target size and the height data of the target specific portion obtained from the target data storage unit. The image target distance measuring device according to claim 2. 5. A target data storage unit in which height data is classified according to the number of specific sites in a target detected by the specific site detection unit, and target data based on the number of specific sites in the target image detected by the specific site detection unit. The image target distance measuring apparatus according to claim 4, further comprising a target determination unit that selects a target of the storage unit. 6. An image pickup means, an image processing means for extracting a target from an image obtained from the image pickup means, and an inertial navigation system for detecting an attitude angle of an aircraft equipped with the image pickup means with respect to an inertial reference coordinate system. , Altitude detecting means for detecting the altitude of an aircraft equipped with the image pickup means, target angle calculating means for calculating an angle of the inertial reference coordinate system of the target extracted by the image means, target angle and altitude of the aircraft In an image target distance measuring device provided with a distance calculating means for calculating the distance between the aircraft and the target and a displaying means for displaying the calculated distance, the lowest point of the target image extracted by the image processing means is measured. An image target distance measuring device comprising a lowest point detection unit for setting points.