JPH07243852A - Water surface monitoring device using stereo image processing - Google Patents

Abstract

PURPOSE:To automatically and objectively measure the average water level of water surface, condition of wave, and transition of average water level with time by measuring the distance from an image pick-up device to a floating object based on the visual difference between two images obtained by two image pick-up devices. CONSTITUTION:In a water-surface monitoring device 200, a camera 202 and a floating object 203 are mounted to a post 201 which is installed so that the upper part is exposed on water surface. A floating object 203 floating on the water surface is gear- locked to the post 201 via an interlocking rod 206 which is inserted into the post 201 so that it can travel freely up and down, thus fixing the floating object 203 so that it cannot be flown away and at the same time it travels up and down on a water surface 205 to be measured and monitored. Then. a visual difference is obtained from coordinate values between two images picked up at a certain time and the distance to the floating object is obtained. The water level on the water surface at a measurement time is obtained from the obtained distance and an average water level, its change with time, the condition etc., of the wave of water surface can be automatically measured from a plurality of water-level data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring the condition of the water surface of a dam, lake or sea, and more particularly to a water surface monitoring device that can be used for dam water level control, automatic wave condition measurement, and the like. is there.

[0002]

2. Description of the Related Art Conventionally, on roads along the coast, vehicle traffic is regulated when high waves occur and the traffic of vehicles becomes dangerous. At this time, the condition of high waves is judged, and whether or not to restrict the traffic of the vehicle is determined by the observer visiting the site or by grasping the situation of the site by monitoring video through the network.

Further, the water level on the water surface of a river such as a river or a lake is measured by an observer reading the value of the water surface in contact with a stanchion with a scale.

[0004]

As described above, in the past, the monitoring of the water surface such as the condition of waves in the sea, lakes, rivers, dams, etc. has hardly been automated. That is, in the conventional water surface monitoring method, an observer actually goes to the observing site, or an image of the water surface is taken by a surveillance camera, and this image is transmitted to the surveillance center by using a communication means such as a public network. The water surface was monitored by grasping the situation or reading the scale in the image and measuring the water level.

However, if an observer goes to the observation site, it is difficult to constantly monitor changes in the water surface that change from moment to moment. In addition, the method of constantly monitoring or measuring the transmitted surveillance image not only requires the labor of the observer, but also has the problem that the data is observed differently depending on the observer when measuring the rippling water level. there were. Moreover, there is a drawback that nighttime monitoring becomes more difficult.

The present invention has been made to solve the above-mentioned problems of the prior art, and is an apparatus for objectively and automatically measuring the average water level on the water surface, the condition of waves, and the temporal transition of the average water level. The purpose is to provide. Another object of the present invention is to provide a water surface monitoring device that can monitor the water surface even at night.

[0007]

In order to achieve the above object, the water surface monitoring apparatus of the present invention floats a floating object on the water surface to be monitored, and images the floating object with two image pickup devices. A configuration in which the distance from the imaging device to the floating object is measured based on the parallax between the two images obtained by the two imaging devices, and the water level of the water surface at the measurement time is measured based on the measured distance. It is characterized by

Further, it is characterized in that the average water level of the water surface, the state of waves on the water surface, or the temporal change of the average water level is measured from the plurality of water surface water level data measured over a certain time interval.

Further, the water surface monitoring apparatus of the present invention is characterized in that a floating object having a function of emitting light is used as the floating object.

Further, the dam control device of the present invention is characterized in that the dam is controlled by using at least one of the water surface monitoring data obtained in claim 1 or claim 2.

Further, the wave condition monitoring device of the present invention is characterized in that the wave condition is monitored using at least one of the water surface monitoring data obtained in claim 1 or claim 2. .

[0012]

Therefore, according to the water surface monitoring apparatus of the present invention,
A floating object floating on the water surface to be monitored is imaged by two imaging devices, and the distance from the imaging device to the floating object is measured based on the parallax between the two images obtained by the two imaging devices. Then, by measuring the water level of the water surface at the measurement time from the obtained distance, or,
The state of the water surface is automatically measured by objectively measuring the average water level of the water surface, the state of the wave on the water surface, or the temporal change of the average water level from a plurality of water level data measured over a certain time interval. Furthermore, by providing the floating object with a light emitting function, it is possible to measure even at night.
As a result, the state of the water surface can be automatically measured objectively and stably regardless of day or night, and without depending on the operator.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the principle of a method for measuring a distance (hereinafter, referred to as a stereo distance measurement) using the principle of triangulation using two image pickup devices (hereinafter, referred to as cameras) will be described with reference to FIG. . X as a coordinate representing the real space,
Y and z are used, and X and Y are used as coordinates that represent a position on the image plane (image pickup plane of the camera). However, in order to distinguish the image planes of the two cameras, XL and YL are used as coordinates indicating the position on the image plane of the left camera, and XR and YR are used as coordinates indicating the position on the image plane of the right camera. . The x-axis and the XL-axis, the x-axis and the XR-axis, the y-axis and the YL-axis, the y-axis and the YR-axis are parallel to each other, and the z-axis is parallel to the optical axes of the two cameras.

The origin O of the real space coordinate system is taken as the midpoint of the projection centers FL and FR of the left and right cameras, and the real space coordinate system (x, y, z) with the origin O is defined as the reference camera coordinate system. Two
I will call it. If the distance between FL and FR is called the baseline length 3 and this distance is 2a, the coordinates of FL and FR in the real space are (-a, 0, 0), (a,
It is represented by 0, 0).

The image plane of the actual camera is on the side opposite to the measurement target with respect to the projection center of the camera, but in order to make it easy to see the geometric quantitative relationship described below, in FIG. It is drawn at the target position.

Assuming that the distance (focal length) between the projection center FL and the left image plane 11 is f, and the distance between the projection center FR and the right image plane 21 (focal length) is also f, the left and right image planes 1 are
The real space coordinates of the image origins OL and OR at 1 and 21 are represented by (-a, f, 0) and (a, f, 0), respectively.
Hereinafter, L and R are used as subscripts indicating the left and right images,
The origin O is called viewpoint 1.

Now, a point p in the real space is a point PL (XL, YL) on the left image plane 11 and a point PR (X on the right image plane 21.
R, YR). In stereo distance measurement, PL and PR are determined on the image plane, and the real space coordinates (x, y, z) of the point p are determined based on the principle of triangulation.
Ask for. Here, since the optical axes of the two cameras are on the same plane and the x axis and the X axis are parallel, Y
L and YR have the same value. A straight line connecting FL and PL,
From the geometric condition that the straight line connecting FR and PR intersect at the point p, the relationship between the coordinates XL, YL, XR, YR on the image plane and the coordinates x, y, z in the real space is

[0019]

[Equation 1]

Alternatively,

[0021]

[Equation 2]

Is required. Where d = XL-XR
Indicates parallax. Therefore, if the corresponding points between the two images obtained by the two cameras, for example, PL and PR are obtained, the coordinate value of the point p in the reference camera coordinate system is determined by the equation 1. Specific examples of the method of obtaining the corresponding points between the left and right images include, for example, “a driving support system using a three-dimensional image recognition technology”, a preprint of the Automotive Engineering Society Academic Lecture 924, pp, 169-172 (1992- 10),
〃 Development of ranging algorithm using stereo image processing 〃, Preprints 924, pp, 15
3-156 (1992-10).

FIG. 2 shows the construction of the first embodiment of the water surface monitoring apparatus of the present invention for measuring the water level on the water surface based on the above-mentioned principle.

In the figure, the water surface monitoring device 200 includes a column 201. The pillar 201 is a pillar for attaching the camera 202 and the floating object 203, and is erected on the seabed, riverbed, or lakebed so that the upper part thereof is exposed above the water surface. The column 201 has a hollow shape, and a connecting rod 206 that is vertically movable in the hollow portion is inserted therein.

Reference numeral 203 denotes a floating object floating on the surface of the water, which is a connecting rod 20 inserted in the column 201 so as to be vertically movable.
It is moored to the support | pillar 201 via 6. As a result, the floating object 203 is fixed so as not to flow, and is configured so as to move in the vertical direction of the measured water surface 205 to be monitored. That is, with this configuration, the floating object 203 always floats following the water surface 205.

Reference numerals 202 and 202 denote two cameras for measuring the distance to the floating object 203 floated on the water surface 205, both of which are attached to the upper part of the column 201. Also,
Reference numeral 204 is a light emitting element provided so that the water surface can be monitored even at night.

With the above arrangement, the floating object 20 is always
3 floats on the water surface 205, and the floating object 203 does not flow. Therefore, it is possible to always take images at substantially the same position within the angle of view of the two cameras 202, 202.

The operation of the water surface monitoring device 200 will be described below. First, a corresponding point in a floating object region is searched between two images captured at a certain time t, a parallax d (t) is obtained from coordinate values on the image between the corresponding points, and a distance z (t ) Is calculated by the equation 3.

[0029]

[Equation 3]

In Equation 3, 2a represents the base length between two cameras, and f represents the focal length of the cameras. At this time, the water level h (t) at the time t can be calculated by Equation 4.

[0031]

[Equation 4]

Here, h (t) represents the height of the water level from the reference plane 207, and H represents the distance from the reference plane 207 to the origin 208 of the reference camera coordinate system.

Next, a method of calculating the average water level will be described. The average water level μ (tn) at a certain time tn is the water level data h (tn-k) measured before the time tn.
(K = 0, 1, 2, 3, ... M-1) is calculated by Equation 5.

[0034]

[Equation 5]

The average water level μ (t
By monitoring the time variation of n),
The fall can be easily estimated.

Next, an index σ (tn) representing the wave state
as,

[0037]

[Equation 6]

And

[0039]

[Equation 7]

The following are conceivable. Which index σ (t
n) also has a large value when the wave is high, and has a small value when the wave is low.

The embodiment of FIG. 2 has been described above.
Besides, the configuration as in the embodiment shown in FIGS. 3 and 4 is also possible.

A second embodiment shown in FIG. 3 will be described.
In the first embodiment of FIG. 2, in order to enable nighttime monitoring,
The floating object itself has the function of emitting light,
In the configuration shown in FIG. 3, a reflector 304 is attached to the floating object 303, and the reflector 304 is illuminated by the illumination 309 provided between the cameras 302 and 302 on the upper part of the pillar 301, thereby enabling nighttime monitoring. Is.

FIG. 4 shows the third embodiment. In FIG. 4, the floating object 403 is not attached to the support column 401, but is attached to the support column 406 provided separately.

By applying the water surface monitoring device of the present invention described above, the water level and the condition of the water surface of the dam can be automatically measured, thereby enabling dam control such as automating discharge of water in the dam. , A dam control device can be realized. Similarly, it is possible to realize a wave condition monitoring device that automatically monitors the state of waves on the coast.

[0045]

As described above, according to the water surface monitoring apparatus of the present invention, a floating object floating on the water surface to be monitored is imaged by two imaging devices, and based on the parallax between the two images obtained. By measuring the distance from the imaging device to the floating object, by measuring the water level of the water surface at the measurement time from the obtained distance, or from a plurality of water level data measured over a predetermined time interval, the average water level of the water surface, Alternatively, since the state of the wave on the water surface or the temporal change of the average water level is objectively and automatically measured, the state of the water surface can be objectively and stably automatically measured without depending on the measurer.

Further, the floating object is provided with a light emitting element or a light emitting function by a reflecting plate, which enables measurement at night. As a result, it becomes possible to objectively and stably automatically measure the state of the water surface day and night.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining the principle of stereo distance measurement.

FIG. 2 is an explanatory view of a first embodiment of the water surface monitoring device of the present invention.

FIG. 3 is an explanatory diagram of a second embodiment of the water surface monitoring device of the present invention.

FIG. 4 is an explanatory view of a third embodiment of the water surface monitoring device of the present invention.

[Explanation of symbols]

 201 prop 202 camera 203 floating object 204 light emitting element 205 measured water surface 206 connecting rod 207 reference surface 208 origin of reference camera coordinate system h (t) water level H distance 301 prop 302 camera 303 floating object 304 reflector 305 measured water surface 306 connection Rod 307 Reference plane 308 Reference camera coordinate system origin 309 Lighting 401 Strut 402 Camera 403 Floating object 404 Light emitting element 405 Water surface to be measured 406 Floating object fixed rod 407 Reference plane 408 Origin of reference camera coordinate system

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area H04N 7/18 C

Claims (5)

[Claims] 1. A floating object is floated on the surface of water to be monitored,
The floating object is imaged by two imaging devices, the distance from the imaging device to the floating object is measured based on the parallax between two images obtained by the two imaging devices, and the measurement is performed. A water surface monitoring device, which is configured to measure the water level of the water surface at a measurement time based on a distance. 2. The average water level of the water surface, the state of waves on the water surface, or the temporal change of the average water level is measured from the plurality of water surface water level data measured over a certain time interval. Water surface monitoring device. 3. A floating object having a function of emitting light is used as the floating object.
The water surface monitoring device described in 1. 4. A dam control device for controlling a dam using at least one of the water surface monitoring data obtained in claim 1 or claim 2. 5. A wave condition monitoring device, characterized in that the wave condition is monitored using at least one of the water surface monitoring data obtained in claim 1 or claim 2.