JP3410020B2 - Liquid level measuring method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level measuring method for measuring a water level of a river, a lake, etc., a tide level of an ocean, etc., and a liquid level of oil etc. (hereinafter, these are collectively referred to as "liquid level"). More particularly, the present invention relates to a liquid level measuring method suitable for measuring a liquid level by taking an image of a liquid level measuring water mark with a camera or the like from a remote place and measuring the liquid level by image processing.

[0002]

2. Description of the Related Art The applicant of the present invention has proposed a technique for measuring a liquid level by installing a water mark on a river or a water mark on the wall of a dam, and taking an image of the water mark from a remote place with a camera to perform image processing. Proposed earlier (JP-A-7-333039, JP-A-8
No. 14992, JP-A-8-145765, Japanese Patent Application No. 7
No. 323220, Japanese Patent Application No. 9-328914), and the fact that it is possible to automatically measure the liquid level with high precision by an actual experiment has started the application to a practical field.

[0003]

[Problems to be Solved by the Invention] It is necessary to measure liquid levels in rivers, etc. even in remote mountains, dams and coasts.
The camera will be installed in a harsh natural environment. For this reason, the front surface of the camera lens may become dirty, birds, insects, etc. may stop in front of the camera, making it impossible to perform normal measurement, resulting in missing data or taking abnormal measurement values as correct measurement values. There is also. Therefore, in order to popularize the liquid level measurement using a camera, it is necessary to be able to cope with such a situation.

An object of the present invention is to provide a liquid level measuring method and apparatus which can cope with a case where normal measurement cannot be performed.

[0005]

The above-mentioned object is to periodically take an image of a water gauge installed at a liquid level measurement place by an image pickup means installed at a remote place, perform image processing on each picked-up image, and perform the water quantity measurement. In the liquid level measurement for obtaining the liquid surface position in contact with the mark, the image of the specific area of the water mark is compared with the template of the specific area stored in the storage device in advance, and the degree of coincidence does not reach the predetermined value. In that case, it is achieved by determining that there is an abnormality.

[0006]

A place that does not change even if the natural environment changes, for example, an image of the tip portion of the water mark is stored as a template in a storage device, and whether or not there is the template portion in the image taken every time is determined. By determining, for example,
It is possible to determine whether there is an obstacle on the front surface of the camera and whether the liquid level can be measured, that is, whether there is a camera abnormality.

[0008]

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a liquid level measuring device according to an embodiment of the present invention. The liquid level measuring device according to this embodiment is installed on an image processing device 1, a monitor device 2, water level indicators 5 and 6 installed on a river 7, and a structure such as a pole (not shown) on the riverbank. The image processing apparatus 1 is configured to output a liquid level measurement result 3 and an alarm 16 when a camera abnormality occurs.

The scaled water mark 5 is erected vertically to the liquid surface of the river 7, and the water mark 6 is installed obliquely to the liquid surface. In the imaged image of the water mark 5, as shown in FIG. 2, the reflection image 5g-2 by the liquid surface 9 and the refraction image from the liquid overlap the real image 5g-1, and the liquid surface position is unknown. , The oblique water mark 6 has its real image 6g-1 and its reflected image 6g-2 or refraction image 6g-3 bent,
A point 10 at which the line of the edge 11 of the real image 6g-1 in the captured image scene of the water gauges 5 and 6 is bent is obtained by image processing, and a reference point and a bending point 10 which are predetermined with respect to the altitude position are set. The liquid level can be calculated from the positional relationship.

As described above, the liquid level position can be directly measured by the image processing by using the oblique water mark, but the shape of the water mark is not limited to that shown in FIG. Alternatively, the vertical water gauge may be omitted and the inclined plates may be provided in multiple stages.

FIG. 3 is a detailed configuration diagram of the image processing apparatus 1. The image processing apparatus 1 includes a main memory 18 that reads a program such as an image processing procedure and a camera control procedure from the external storage device 23, a CPU 17 that executes the program loaded on the main memory 18, and a captured image captured by the camera 4. An image processing processor 20 that processes the image according to an instruction from the CPU 17 and displays it on the monitor 2 or outputs the processing result, an image memory 21 that stores a captured image captured from the camera 4 and an image of the processing result, the CPU 17 and the image. A bus 19 connecting the processor 20 and an external interface 22 connected to the bus 19 are provided, and the output of the processing result and the alarm output are external to the image processing apparatus 1 via the interface 22 (for example, monitoring). It is output to a staff room or a central control room at a remote place connected via a communication line.

In the image processing apparatus 1 according to this embodiment,
The shape pattern 14 of the upper end portion of the vertical water gauge 5 and the shape pattern 15 of the upper end portion of the oblique water gauge 6 shown in FIG. 2 taken by the camera 4 when the liquid level measuring device is installed are stored in the external storage device 23. It has been stored. And this pattern 14, 1
By using 5, it is determined whether or not there is an abnormality in the camera, the power supply, the communication cable, etc., and it is determined that there is an abnormality (generally referred to as "camera abnormality") and normal measurement cannot be performed. In this case, the alarm 16 is output.

FIG. 4 is a flow chart showing the procedure of setting processing of the liquid level measuring device, which is performed once offline when the liquid level measuring device is installed. First, in step A, the captured image of the water mark is captured. Next, in step B, the feature amount used to determine whether or not normal measurement is possible is cut out from the captured image and stored in the external storage device 23. As the data of the feature amount used in this embodiment, reference numeral 1 in FIG.
The grayscale template data of the portion 4 and its position data, and the grayscale template data of the portion 15 and its position data are adopted.

In the next step C, the position of the first reference point (scale "3" in the illustrated example) shown in FIG. 2 is designated on the captured image. Similarly, in step D, the second reference point is designated. Specify the position of (4 in the example shown) on the captured image,
The actual distance between the two reference points is input to the image processing device (step E).

Then, the distance conversion coefficient ε between the world coordinate system and the coordinate system of the captured image is calculated and obtained, and the external storage device 2
3 (step F). Next, the position of the first reference point in the world coordinate system, that is, the altitude value is input (step G), and information about this reference point is stored in the external storage device 23 (step H). By performing the processing of these steps C to H, it becomes possible to convert the position on the captured image to the position in the world coordinate system.

FIG. 5 is a flowchart showing an on-line processing procedure of the liquid level measurement processing which is repeatedly performed at a predetermined cycle, for example, every 10 minutes or every hour. In this online processing, first, an image captured by the camera is captured in step J, and then a camera abnormality detection processing K, which will be described in detail later, is performed. If the abnormality detection process determines that there is an abnormality, the process proceeds to step P to output an alarm. If the abnormality is “none”, the process proceeds to step L, and the tilt amount water mark 6 in FIG.
Is processed to obtain the inflection point 10 of the edge 11, that is, the water surface position 9, and this water surface position is converted into the water surface boundary of the vertical water gauge 5 (step M), and this water surface boundary value is stored in the external storage device 23. It is converted into a liquid level position in the world coordinate system using the reference point information and the value of ε read from, and the conversion result, that is, the liquid level measured value is output (step N).

FIG. 6 is a flowchart showing the detailed processing procedure of the camera abnormality detection processing. In the liquid level measuring device, if there is an obstacle such as a bird in front of the camera lens and the image of the water mark cannot be captured, or if a failure occurs and the captured image remains captured, the captured image remains in memory as is. There is a possibility that the previous image cannot be updated with another captured image.

Therefore, in this camera abnormality detection processing, first, the counter CNT is cleared to 0 in step K-50, and in step K-100, the characteristic amount stored in the external storage device 23, in this case, FIG. The template of the part 14 and the position information thereof are compared with the corresponding image in the input image, and if they do not match, it is determined as "abnormal" and the process proceeds to step K-500. If it is determined to be normal, the process proceeds to step K-300, and the template indicated by reference numeral 15 in FIG. 2 and its position information are compared with the corresponding image in the input image (step K-40).
0). If they do not match as a result of comparison, step K-5
Proceed to 00.

At step K-500, the value of the counter CNT is incremented by the value 1, and it is determined whether the content of the counter is "3" or less (step K-600). When the content of the counter is "3" or less, the process proceeds to step K-800 to capture the image again, and the process returns to step K-100. Then, if the templates 14, 15 and the position information are not matched three times in succession, the process proceeds from step K-600 to step K-700 to determine "abnormal" and proceeds to step P in FIG.

[Normal] according to the determination result of step K-400
That is, if there is no camera abnormality, step K-45
Proceed to 0 to clear the contents of the counter CNT to 0, and proceed to the next Step K-460.

In step K-460, it is confirmed whether or not the water surface has changed. This is to determine whether or not a failure has occurred in which the image once captured cannot be updated with the next captured image, and it should be captured and image processed for water level measurement depending on whether the water surface changes. This is to see if this image has been updated from the previous image. In rivers etc., the condition of the water surface is constantly changing due to windy waves, so if the degree of disagreement in the water surface image is more than a predetermined value compared to the previous image, it is determined that there is a water surface change (no camera abnormality), Go to step L in FIG.

If it is determined that there is no change in the water surface, the process proceeds to step K-850, the value of the counter CNT is incremented by the value 1, and it is determined whether the content of the counter is "3" or less. If the counter content is '3' or less, step K-
The process proceeds to step 870 to capture the image again, and the process returns to step K-460. If it is determined that the water surface has not changed for three consecutive times, steps K-850 to K-860 are performed.
Then, it is determined that there is an abnormality and the process proceeds to step P in FIG.

For example, even if a bird or a spider stops in front of the camera and an abnormality is found at steps K-200 and K-400, the bird will return to normal once it has taken off, so it is possible to make a single determination. It is premature to assume that there is an abnormality. In addition, even if the update of the captured image is disabled only this time, there are many cases where the image is re-acquired again. Therefore, in the present embodiment, as described above, if there is an abnormality, the number of
Since the re-capturing of images and the determination of whether there is an abnormality are repeated only once, a reliable determination can be made, and the number of maintenance personnel required when an abnormality occurs can be reduced.

In the above embodiment, only the abnormality alarm 16 is output when an abnormality is detected. However, it is possible that the abnormality is caused by dirt on the window on the front surface of the lens. It is also possible to automatically operate the wiper or the like attached to the device, detect the abnormality again and again after this, and output an abnormality alarm if the abnormality still occurs.

[0026]

As described above, according to the present invention, an abnormal alarm is output when a camera abnormality occurs, so that it is possible to avoid unintentional failure. In addition, even if a camera error occurs, it will be judged that there is a camera error after a number of retries, so it will be possible to recover any abnormality that can be automatically restored, and the number of maintenance personnel can be reduced. An abnormal alarm can be output only when there is an abnormality.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a liquid level measuring device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a water level gauge shown in FIG.

FIG. 3 is a detailed configuration diagram of an image processing apparatus.

FIG. 4 is a flowchart showing a processing procedure of offline processing of the image processing apparatus.

FIG. 5 is a flowchart showing a processing procedure of online processing of the image processing apparatus.

6 is a flowchart showing a detailed procedure of camera abnormality detection processing shown in FIG.

[Explanation of symbols]

1 ... Image processing device, 2 ... Monitor, 3 ... Data, 4 ... Camera, 5, 6 ... Water mark, 7 ... River, 16 ... Camera abnormality alarm output.

Front page continuation (72) Inventor Takayuki Yoneoka 5-2-1 Omika-cho, Hitachi City, Ibaraki Hitachi Process Computer Engineering Co., Ltd. (72) Takero Kasai 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Ltd. Omika Plant (72) Inventor Toshio Hata 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Omika Plant (72) Inventor Akio Tsujikawa 5-chome, Omika-cho, Hitachi City, Ibaraki Prefecture 2-1-1 Hitachi Ltd. Omika Factory (72) Inventor Ken Saito 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi Ltd. (72) Inventor Masakatsu Ishitsubo 4-chome Kanda Surugadai, Chiyoda-ku, Tokyo Address Hitachi, Ltd. (56) Reference JP-A-9-161076 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01F 23 / 00-25 / 00

Claims (6)

(57) [Claims] 1. A liquid level gauge installed at a liquid level measurement location is periodically imaged by an imaging means installed at a remote location, and each captured image is image-processed to determine a liquid level position in contact with the water level gauge. In the liquid level measuring method to be obtained, the image of the specific area of the water mark is compared with the template of the specific area stored in the storage device in advance, and if the degree of coincidence does not reach the predetermined value, it is determined that there is an abnormality. A liquid level measuring method characterized by: 2. In claim 1, when it is determined that there is an abnormality, the process of capturing the captured image again and determining the presence / absence of the abnormality using the template is repeated a predetermined number of times. A liquid level measuring method characterized by outputting an abnormality alarm when 3. A liquid level position which is in contact with the water level mark is measured by periodically taking an image of a water level mark installed at a liquid level measuring place by an image pick-up means installed at a remote place. In the liquid level measuring method to be obtained, the image of the liquid surface in the captured image which is not determined to be abnormal according to claim 1 or 2 is obtained.
Compared with the liquid surface image in the previous captured image, one of both liquid surface images
If the criticality is above a certain value, or one of the both liquid surface images
If the criticality is equal to or greater than the specified value and it is determined that there is an abnormality,
Abnormality by capturing the captured image and comparing the liquid level image
Repeat the process to determine the number of times a predetermined number of times
A liquid level measuring method, wherein the value of the liquid surface position obtained by the image processing is adopted as a measured value when there is no determination of abnormality with a constant number of consecutive times . 4. A water mark installed at a liquid level measuring place, an image pickup means for picking up the water mark from a distant place, and image processing of each picked-up image periodically picked up by the image pickup means. In the liquid level measuring device including an image processing unit that obtains a liquid surface position in contact with the water level indicator, a storage unit that stores in advance an image of a specific region of the water level mark as a template, and an image captured by the image capturing unit. A liquid level measuring device, comprising: a determination unit that compares an image of the specific region therein with the template and determines that there is an abnormality when the degree of coincidence does not reach a predetermined value. 5. The process according to claim 4 , wherein when it is determined that there is an abnormality, the process of re-taking the captured image and determining the presence / absence of the abnormality using the template is repeated a predetermined number of times and the presence of the abnormality continues for the predetermined number of times. A liquid level measuring device comprising means for outputting an abnormal alarm at the time. 6. A water mark installed at a liquid level measuring place, an image pickup means for picking up the water mark from a remote place, and image processing of each picked-up image picked up by the image pickup means periodically. wherein the liquid level measuring device and an image processing means for determining the liquid level position in contact with the weight aqueous preparations, liquid level in the abnormality determination is no and the captured image according to claim 4 or claim 5 Te
Image of both liquid surface images compared with the liquid surface image in the previous captured image.
When the degree of coincidence of images is equal to or greater than a predetermined value, or both surface images
When it is judged that there is an abnormality because the degree of coincidence of images is more than a predetermined value
Abnormality due to recapture of captured image and comparison of liquid surface image
The process of determining the presence / absence is repeated a predetermined number of times before there is an abnormality.
Note that the liquid level measuring device is provided with means for adopting a value of the liquid surface position obtained by the image processing as a measurement value when there is no abnormality determination when a predetermined number of consecutive times .