TW201447241A - Method of water level measurement - Google Patents

Abstract

A method of water level measurement is used to measure the level of water. The method includes an image reading step, an image adjusting step, and a water level computing step. The image reading step computes the real size of a pixel from an original image that fetching by a computer. The image adjusting step adjusts the original image to a horizontal image according to the angle between the camera's view-angle line and horizontal line, and selects a plurality of regions of interest (ROI) from the horizontal image. The water level computing step estimates the corresponding water surface position of each region of interest, and then computes the water level of the original image according to the plurality of water surface positions derived from the plurality of regions of interest.

Description

Multi-block water level measurement method

The invention relates to a multi-block water level measuring method, in particular to a multi-block water level measuring method for calculating a water level height through image analysis processing technology.

Taiwan is located in the western Pacific monsoon region, which is extremely vulnerable to disasters. On average, it has been invaded by the typhoon in the western Pacific for more than four times a year. The heavy rains brought by the typhoon often lead to frequent floods and serious economic losses. In addition, with the global warming and climate change, the rainfall patterns have changed. In recent years, extreme rainstorms of heavy rainfall have been common in recent years. Extreme rainfall patterns are likely to cause urban areas to be unable to eliminate excess rainfall and areas in a short period of time. Flooding is not enough to flood, seriously threatening the lives and property of the people.

Accordingly, the monitoring and early warning of floods has always been the primary target of disaster prevention. After receiving the manual notification, the known flooding warning method is to send relevant personnel to the flooding site to measure the water level by a conventional contact water level measuring device. The measurement results are returned to the disaster response center for statistical processing to determine the flooding situation, and then an alarm is issued. However, this method often wastes a lot of manpower for flooding the on-site water level measurement and result aggregation statistics. In order to solve the problems faced by the above-mentioned conventional flood warning method, in the low-lying areas with high flooding probability, the conventional contact water level measuring device is usually resident to monitor the water level at any time and automatically return through wired or wireless communication. Pass the measurement results to save disaster relief resources.

However, since the conventional contact type water level measuring device has to be inserted into the water for measurement, it is often difficult to measure successfully when the water flow is in a hurry, and even there is a risk that the device is directly washed away or destroyed. In addition, the measuring range of the conventional contact water level measuring device is often affected by the device itself. The size limit, when the flooding depth is too high, is prone to the situation that the device itself is submerged and the measurement function is lost.

In order to solve the problems faced by the above-mentioned conventional flood monitoring method, for example, the content of the patent application of the "Lens Optical Image Water Level Measuring Device and Method" of the Republic of China No. 201024687 discloses a conventional non-contact water level measurement. The method can inject a water source into a body of water by a non-contact method, and take a water surface image to measure the water level of the water body. The device and method thereof of the patent can improve the conventional contact type water level measuring device to be inserted into the water, and have the disadvantages of easy measurement failure or damage to the device, but the device still needs to be installed at each location to be detected, and still has a cost. The higher the problem, it is difficult to implement a wide range of flood monitoring. Moreover, since the water body tends to be turbid and full of debris when flooded, the method of irradiating with a laser light source also has the problem that the water level cannot be accurately measured.

In summary, the conventional non-contact water level measurement method can achieve the purpose of "measuring the water level in a non-contact manner", but there are still "the setting cost is too high" and "the measurement accuracy may be affected by the water color and Concerns such as the influence of drifting water in water, it is easy to derive different limitations and shortcomings in actual use, and there are inconveniences that need further improvement to improve its practicability.

The object of the present invention is to improve the above-mentioned disadvantages, and to provide a multi-block water level measurement method, which only needs to analyze and process the image captured by the conventional surveillance camera, and can measure the water level height, thereby reducing the system installation cost.

Another object of the present invention is to provide a multi-block water level measurement method. The multi-block water level measurement method determines the water level height by image recognition, and is not affected by water color and water drifting during measurement, and has an increased water level measurement. The effect of accuracy.

Another object of the present invention is to provide a multi-block water level measurement method, which uses a gradient operator edge search method to detect a boundary position in an image. A decision block is selected, and the gradient operation sub-edge search method is applied to the judgment block, which has the effect of improving the operation speed.

A further object of the present invention is to provide a multi-block water level measurement method, wherein the multi-block water level measurement method selects a plurality of the determination blocks in the image, and generates a plurality of water surfaces according to the plurality of determination block operations. The position, together with the plurality of water surface positions to calculate the water level height, can avoid the effect that the water level measurement result is seriously affected when the judgment block is blocked by the shielding object, and the reliability of the method is improved.

In order to achieve the foregoing objectives, the technical content of the present invention includes: a multi-block water level measurement method, wherein a raw image is captured by a monitoring lens, and a computer system measures the water level of the original image, including The following steps: an image reading step, wherein the original image is read by the computer system, and the actual size represented by a pixel is calculated according to the size of the original image; an image correction step, if the angle of view of the monitoring lens and the horizon If the angle is not equal to zero, the original image is horizontally corrected according to the angle; and a plurality of determining blocks are circled from the original image; and a water level estimating step is to apply a gradient operator edge search for the determining block a method for calculating image gradient values and image boundary values of each pixel of the post-image; and estimating a boundary projection value according to the image boundary value to estimate at least one boundary position; and determining a water surface position according to the boundary position, and determining The plurality of water surface positions generated by the plurality of determining blocks are used to calculate a water level determination result; finally, the original The actual size of the image represented by the pixel is determined to calculate the water level of the water represented by the result.

The multi-block water level measurement method of the present invention further includes a gray scale processing step, which is performed after the image reading step is completed, and performs gray scale operation on the original image, and the original image is subjected to gray scale operation. The brightness belongs to a gray scale range.

The multi-block water level measurement method of the present invention further includes an image enhancement step, which is performed after the gray scale processing step is completed, and adjusts the original image by gray scale operation to uniformly distribute the brightness on the gray scale Between the maximum and minimum values of the gradation range.

The multi-block water level measurement method of the present invention, wherein the gradient operator sub-edge search method calculates the image gradient and the image boundary value of each pixel of the post-image as follows: Where G represents the image gradient, E represents the image boundary value, f(x, y) is the grayscale value of the pixel coordinate value of the judgment block (x, y), and Gx represents the horizontal direction of the judgment block. The gradient value, Gy represents the gradient value of the vertical direction of the judgment block, and ω is a threshold value.

The multi-block water level measurement method of the present invention, wherein the threshold value is obtained using a Canny edge detection operator.

In the multi-block water level measurement method of the present invention, if the image correction step selects a total of L determination blocks, and the size of the determination block is M×N pixels, the boundary projection value is estimated and the boundary position is estimated. The method is as follows: Where (x, y) represents the pixel coordinate value of the above-mentioned judging block, and I(y) represents a boundary projection value of a horizontal height in the above-mentioned judging block, and μ is a standard value. When the boundary projection value exceeds the standard value, the horizontal height coordinate is set to a boundary position.

In the multi-block water level measurement method of the present invention, the judgment block has a total of M pixels in the horizontal direction width and a total of N pixels in the vertical direction, and the standard value is M/2 pixels.

In the multi-block water level measuring method of the present invention, the method of determining the position of the water surface is to regard the boundary position as the water surface position.

In the multi-block water level measuring method of the present invention, the method for determining the position of the water surface is the boundary position of the at least one boundary position that changes with time as the water surface position.

In the multi-block water level measurement method of the present invention, the method for estimating the water level determination result is to obtain an average of the plurality of water surface positions as the water level determination result.

The multi-block water level measuring method of the present invention, wherein the method for calculating the water level determining result sets an allowable range, and obtains an average of the water surface positions falling within the allowable range among the plurality of water surface positions as the Water level judgment result.

In the multi-block water level measurement method of the present invention, the water level determination result previously measured according to the multi-block water level measurement method is used to set the allowable range.

The multi-block water level measuring method of the present invention, wherein the multi-block water level measuring method previously measures one water level determination result plus an error value as the allowable range.

The multi-block water level measurement method of the present invention, wherein the average value of the plurality of water level determination results previously measured by the multi-block water level measurement method is added by the product of the standard deviation and an allowable ratio as the product Allowable range.

The multi-block water level measuring method of the present invention, wherein the multi-block water level measuring method further comprises a filtering processing step, after selecting a plurality of determining blocks in the image correcting step, filtering each of the determining blocks Process to eliminate noise.

The multi-block water level measuring method of the present invention, wherein the filtering processing method used in the filtering processing step is intermediate value filtering.

1‧‧‧Monitor lens

2‧‧‧ computer system

3‧‧‧Image Server

S1‧‧‧Image reading step

S2‧‧‧ Grayscale processing steps

S3‧‧‧ Image Enhancement Steps

S4‧‧‧Image correction procedure

S41‧‧‧Level Correction Substep

S42‧‧‧Judgement block circle selection substep

S5‧‧‧Filter processing steps

S6‧‧‧ water level estimation steps

S61‧‧‧Boundary estimation substep

S62‧‧‧Boundary projection substep

S63‧‧‧ Water level determination sub-step

S64‧‧‧Result calculation substeps

A‧‧‧ original image

B‧‧‧Information points

△H‧‧‧image scale

θ ‧‧‧ horizontal correction angle

V‧‧‧ perspective

G‧‧‧ horizontal line

R‧‧‧Judgement block

B‧‧‧post image

H ₀ ‧‧‧ horizontal line coordinate value

The actual height of the H _t ‧‧‧ horizontal line

G‧‧‧ image gradient values

E‧‧‧ image boundary value

I‧‧‧ boundary projection value

H‧‧‧Boundary position

W‧‧‧ water surface location

W ^C ‧‧‧ water level determination result

Figure 1 is a system architecture diagram of a preferred embodiment of the multi-block water level measurement method of the present invention

Figure 2: Operation flow chart of a preferred embodiment of the multi-block water level measurement method of the present invention

Figure 3: Internal flow chart of the image correction step of the preferred embodiment of the multi-block water level measurement method of the present invention

4 is a schematic diagram of a monitoring lens of a preferred embodiment of the multi-block water level measuring method of the present invention

Figure 5: Internal flow chart of the water level estimation step of the preferred embodiment of the multi-block water level measurement method of the present invention

The above and other objects, features and advantages of the present invention will become more <RTIgt; (pixels) is the smallest unit of an image used to represent the resolution of the image. For example, if the resolution of the image is 1024×768, it means that the image is common (1024× 768 = 786432) pixels are understood by those of ordinary skill in the art to which the present invention pertains.

The "color level" as used throughout the present invention refers to the degree of shading of the color component or brightness exhibited by the pixel, for example, the red (R), green (G), and blue (color) images. B) The range of the color gradation of the component is 0 to 255; alternatively, the gradation range of the luminance of the gray-level image may range from 0 to 255, which is generally in the technical field to which the present invention pertains. Knowledge people can understand.

The "probability distribution" as used throughout the present invention refers to the probability distribution of the gradation range of all pixels in an image, that is, the distribution of the gradation of each pixel of the image, for example, the brightness of a grayscale image. The range is 0~255 (that is, 256 levels), and the probability distribution includes the following information: the number of pixels with gradation of 0, the number of pixels with gradation of 1, the number of pixels with gradation of 2, and the gradation The number of pixels of 255 is understood by those of ordinary skill in the art to which the present invention pertains.

Please refer to FIG. 1 , which is a system architecture diagram of a preferred embodiment of the multi-block water level measurement method of the present invention. Wherein, a computer system 2 (for example, a conventional computer host, a file server, or a cloud server) is connected as an execution architecture by at least one monitoring lens 1 (for example, a conventional surveillance camera, a network camera, or a nighttime infrared camera). The at least one monitoring lens 1 can capture an original image A, such as a single or continuous image, and the original image A can be a color or grayscale image. The original image A There are several pixels, each pixel has a color gradation, and the range of values that can be represented by the color gradation is the gradation range of the image. The computer system 2 is coupled to the at least one monitoring lens 1 to receive the original image A, and according to the operation flow disclosed in the preferred embodiment of the multi-block water level measuring method of the present invention, is used to measure the at least The height of the flooded water level in the area where the lens 1 is located. In this embodiment, the original image A is described with a single color image as an implementation aspect, but not limited thereto, and the like, and can be applied to water level measurement of black and white or continuous images, which is the present invention. Those skilled in the art can understand that it is not described here.

In addition, an image server 3 is preferably connected in series between the at least one monitoring lens 1 and the computer system 2 for receiving and collecting the original image A captured by the at least one monitoring lens 1 and performing time sampling processing or imaging. The compressed image is processed, and the processed original image A is transferred to the computer system 2. Therefore, when the number of the at least one monitoring lens 1 is too large, the original image A of the captured image is too fine, or the original image A is a continuous image having a long length, the image file size formed is too large, thereby avoiding The computer system 2 is unbearable.

Please refer to FIG. 2, which is a flow chart of the operation of the preferred embodiment of the multi-block water level measurement method of the present invention. The multi-block water level measurement method includes an image reading step S1, a grayscale processing step S2, an image enhancement step S3, an image correction step S4, a filtering processing step S5, and a water level estimation step S6, respectively The narrative is as follows.

The image reading step S1 first reads an original image A by the computer system 2. In the embodiment, the original image A is an RGB image, and the original image A is The color scale ranges from 0 to 255, but the invention is not limited thereto. The original image A is recorded by a monitoring lens 1 and the monitoring lens 1 is disposed at a fixed position. Therefore, the actual size represented by the original image A can be preset in the computer system 2. The image reading step S1 then calculates an image scale ΔH according to the pixel size of the original image A and the actual size represented by the original image A, which can be used to convert the actual size represented by the arbitrary pixel value. For example, suppose that the original image A taken by a surveillance lens 1 includes a commander station, and the actual height of the commander is known to be 500 cm. If the computer system 2 reads the original image A and measures the height of the commander. For 100 pixels, it can be inferred that one pixel represents 5 cm, and the image scale ΔH is 5 (cm/pixel). When the image reading step S1 is completed, the grayscale processing step S2 is started.

The gray scale processing step S2 is to perform gray scale processing on the original image A. The main principle is to convert the tone of the original image A to the average according to the color gradation of the red, green and blue components of each pixel of the original image A. The color scale ranges from 0 to 255, and the tone conversion mode is preferably as shown in the following formula (1): f(x, y) = 0.299 × R (x, y) + 0.587 × G (x, y)+0.114×B(x,y) (1) where (x,y) is the pixel coordinate value, f(x,y) is the brightness of the grayscale image, R(x,y), G(x,y ), B(x, y) represents the gradation of the three gamuts of red, green, and blue. The original image A is converted to form a grayscale image, and the color is relatively easy to process.

The image enhancement step S3 performs image enhancement processing on the grayscale image to obtain a enhanced image. The main principle is that the probability distribution of the grayscale range of the grayscale image is averaged to 0~255, thereby strengthening the grayscale. The contrast value of the image. For example, if the probability distribution area of a grayscale image is between 25 and 100, which is a case where the screen is dark, the probability distribution area can be adjusted to 0 to 255 through the image enhancement step S3, so as to facilitate subsequent steps. Interpret the details. Since the picture quality of the original image A captured by the monitoring lens 1 is very susceptible to weather, time, and the like, resulting in blurring of the image, generation of noise, excessive color tone or excessive darkness, the image enhancement step S3 is performed. After image enhancement, it is more accurate Observe the changes in detail.

However, the grayscale processing step S2 and the image enhancement step S3 are selectively executable. In other words, if the original image A itself is a gray scale image, the gray scale processing step S2 can be omitted; similarly, if the brightness of the gray scale image is evenly distributed in the grayscale scale range, the maximum value and the minimum value are Between the values, the image enhancement step S3 can be omitted. Accordingly, the grayscale processing step S2 and the image enhancement step S3 are not essential steps, and can be easily considered by those skilled in the art to which the present invention pertains.

As shown in FIG. 3, it is an internal flowchart of the image correction step S4 of the preferred embodiment of the multi-block water level measurement method of the present invention. The image correction step S4 includes a horizontal correction sub-step S41 and a determination. The block circle is selected in step S42. The horizontal correction sub-step S41 is to perform horizontal correction on the enhanced image to obtain a horizontal image. Since the angle of view of the at least one monitoring lens 1 is not directly horizontally looking at the object to be detected, it is necessary to correct the level of the object to be detected. To facilitate the detection of flooding depth.

More specifically, please refer to FIG. 4 again, the at least one monitoring lens 1 is usually disposed at a fixed position, so that the computer system 2 has preset a horizontal correction angle θ for any of the monitoring lenses 1 The horizontal correction angle θ is an angle between the viewing angle V of the monitoring lens 1 and a horizontal line G. The horizontal correction angle θ can be used to horizontally correct the image from each of the monitoring lenses 1, and the horizontal correction mode is as follows ( 2): x' = x cos( θ ) + y sin( θ ) y' =- x sin( θ )+ y cos( θ ) (2) where (x, y) is the pixel coordinate of the enhanced image The value, (x', y') is the pixel coordinate value of the horizontal image. The horizontal correction sub-step S41 is selectively executable. For example, when a monitoring lens 1 is directly viewed from the object to be detected, the enhanced image is a horizontal image. The computer system 2 presets the horizontal correction angle θ to be equal to zero. That is, the horizontal correction sub-step S41 is omitted.

The determining block circle sub-step S42 selects a plurality of determining blocks R from the horizontal image, and the plurality of determining blocks R are respectively distributed in the horizontal image, and each of the determining blocks R is better between each other. Do not overlap each other. The size of the determining block R is M×N pixels, that is, the horizontal width of the determining block R has a total of M pixels, and the vertical direction has a total of N pixels, and the size of the determining block R is occupied. More than five percent of the original image A is preferred. In addition, the determination block image R includes a horizontal line G, the actual height of the horizontal line G is H _t (cm), and the horizontal height coordinate value of the horizontal line G is H ₀ , that is, the horizontal line G is located in the judgment. The H ₀ pixel of the vertical position in the block R, and 0 ≦ H ₀ <N.

The filtering processing step S5 performs filtering processing on the determining block R. The main principle is to perform a detection comparison on the determining block R by using a mask, which is a conventional median filter (median) Filter), and the size of the mask is preferably 1×(M/2), and M/2 is half of the width of the determination block R, and the pixel of the determination block R is covered by the mask. The intermediate value is replaced. Thereby, the noise of the determination block R can be reduced, and since the water level usually only rises or falls horizontally, the filtering process does not filter out the water level information component, and the determination block R can be further provided through the filtering process. Evaluate the water level efficiently. However, the filtering process step S5 may also use other conventional filtering processing methods such as average value filtering, Gaussian value filtering or Laplacian value filtering, and the invention is not limited thereto.

Through the above steps, the original image A can be subjected to a continuous image processing process. The filtering process S5 finally generates a plurality of post-images B, which are of a size of M×N pixels and a color scale range of 0. A grayscale image of ~255 for subsequent water level estimation. The filtering processing step S5 is selectively executable. For example, when an original image A is sufficiently clear and does not contain noise that may affect the operation result of the subsequent step, it is not necessary to filter the determination block R selected in the original image A. Processing, so this step can be omitted, and the determination block R is a post-production image B.

Please refer to FIG. 2 and FIG. 5, which are internal flowcharts of the water level estimating step S6 of the preferred embodiment of the multi-block water level measuring method of the present invention. The water level estimating step S6 includes a boundary estimating sub-step S61. a boundary projection sub-step S62, a water level determination sub-step S63 and a result calculation sub-step S64, the boundary estimation sub-step S61 is a gradient operation sub-edge search method, the main principle is to calculate each pixel in the post-production image B The image gradient value G, and the image boundary value E of each pixel is calculated according to the image gradient value G. The image boundary value E is 1 or 0, which represents that a pixel is a boundary or not a boundary. The calculation method of the image gradient value G and the image boundary value E is as shown in the following equations (3), (4) and (5):

Where f(x, y) is the gray scale value when the pixel coordinate value of the post-image B is (x, y), as shown in the above formula (1), and 0≦x<M and 0≦y <N; Gx represents the gradient value of the horizontal direction of the post-image B, Gy represents the gradient value of the vertical direction of the post-image B, and ω is a threshold. When the image gradient value G of one pixel (x, y) exceeds the threshold ω , the image boundary value E(x, y) of the pixel (x, y) is set to 1; otherwise, the pixel is set (x, y) The image boundary value E(x, y) is 0. The threshold ω is preferably generated using a Canny edge detector (Manny edge detector) operation.

It should be noted that if the determining block circle sub-step S42 selects a total of L decision blocks R, the foregoing steps will generate L post-images B, so the boundary estimation sub-step S61 must be repeated L times to respectively The image boundary value E of each pixel in each of the post-images B is calculated.

The boundary projection sub-step S62 accumulates the image boundary value E of each level in each of the post-images B to generate a boundary projection value I, and determines whether the level is a boundary according to the boundary projection value I. position. The projection accumulation method and the boundary position determination method are as shown in the following equations (6) and (7):

Wherein, since (x, y) is the pixel coordinate value of the post-production image B, y is a horizontal height coordinate of the post-production image B, The sum of all image boundary values E of the horizontal height coordinate y is the boundary projection value I(y) of the post-image B at the horizontal coordinate y. When the boundary projection value I(y) exceeds a standard value μ , the horizontal height coordinate y is set to a boundary position H. In the embodiment, the standard value is preferably the width of the post-image B. One-half (M/2).

If the post-production image B generates only one boundary position H in the boundary projection sub-step S62, the water level determining sub-step S63 directly sets the boundary position H to a water surface position W. However, in the post-production image B, in addition to the water surface, other objects may be determined as the boundary position H, such as passing by a passerby, a vehicle or other obscuring object, etc., resulting in the boundary position H generated by the boundary projection sub-step S62. The number is more than one. Therefore, in order to estimate the water level more accurately, the water level determining sub-step S63 can analyze and compare the plurality of boundary positions H. The main principle is to compare the original image A received by the computer system 2 at different times, and the different time is received. After the original image A is generated, the image B is generated by the boundary projection sub-step S62, and a plurality of boundary positions H are respectively generated. Since the water level generally rises or falls with time during flooding, the water surface should be in each of the post-images B. By changing the boundary position H, by comparing the plurality of boundary positions H, the boundary position H maintained at the fixed height can be excluded, and only the boundary position H that changes with time is saved, and is set to a water surface position W.

However, if a post-production image B is severely blocked by the obstructing object, causing the image of the water-free image in the post-production image B, the water surface position W calculated according to the post-production image B is not actually flooded, and Inventive multi-block water level measurement method The bit measurement results have a serious impact. In order to solve this problem, in the embodiment, the determining block circle selection sub-step S42 selects a total of L determination blocks R, so the water level determination sub-step S63 generates a total of L water surfaces according to the L post-production image B operations. Location W.

In detail, the water level determining sub-step S63 can obtain the average of the L water surface positions W as a water level determination result W ^C to offset the influence of a few false positives on the water surface position W of the flooded water surface; or The water level determining sub-step S63 can set an allowable range, and shave all the water surface positions W that fall outside the allowable range, and then obtain the average of the remaining water surface positions W falling within the allowable range as the water level. The result of the determination is W ^C .

More specifically, the preferred embodiment of the multi-block water level measuring method of the present invention continuously receives the original image A captured by the monitoring lens 1 by the computer system 2, and continuously updates the area where the monitoring lens 1 is located. The accumulated water level is so high that the water level determining sub-step S63 can set the allowable range based on the previous (or previous) measurement results. For example, by presetting a value of error ε , ± ε as the allowable range, where The water level determination result W ^C obtained from the previous measurement. Accordingly, the determination method of the water level determination result W ^C can be divided into the following three cases:

(1) When the L water surface positions W all fall within the allowable range, the water level determination result W ^C is an average of the L water surface positions W, as shown in the following formula (8):

(2) When one of the water surface positions W ^j is outside the allowable range, the water level determination result W ^{C is} as shown in the following formula (9):

(3) When all the water surface positions W fall outside the allowable range, the water level judgment result obtained by the previous measurement can be directly considered. As the water level determination result W ^C , or the water level determination result of the previous several times The average of ... is taken as the water level determination result W ^C , and the present invention is not limited thereto. Wherein, W ^{i is the i-th of} the L water surface positions W, and when a plurality of the L water surface positions W fall outside the allowable range, the above formula (9) can be applied several times. The calculation of the water level determination result W ^C can be easily understood by those having ordinary knowledge in the technical field to which the present invention pertains.

It should be noted that the error value ε can be generated by a statistical principle operation, in addition to being preset by the user. For example, the computer system 2 can determine the result based on the previous water level. , ... calculates a standard deviation, and multiplies the standard deviation by an allowable magnification as the error value ε . Among them, the allowable magnification is usually 2 times, 1 time or 1.5 times, and the like.

The result calculation sub-step S64 compares the water level determination result W ^C with the horizontal height coordinate value H ₀ of the horizontal line G, and according to the actual height H _t (cm) of the horizontal line G and the image scale ΔH (cm/pixel), calculate the actual height represented by the water surface position. For example, when the foregoing step determines a water level determination result W ^C , the actual height represented by the water level determination result W ^C is H _t +(W ^C −H ₀ )×ΔH(cm), which is the monitoring lens. The height of the flooded water level in a photographed area.

In summary, the multi-block water level measurement method of the present invention starts from the image reading step S1, in which the computer system 2 reads an original image A, through the gray-scale processing step S2, the image enhancement step S3, In the subsequent steps of the image correcting step S4 and the filtering process S5, the image analysis processing is performed on the original image A to generate a post-image B, and then the water level estimating step S6 is performed to obtain a water level height, which is the original image A. The height of the flood. Accordingly, the invented multi-block water level measurement method can achieve the purpose of calculating the water level height through image analysis processing technology.

Therefore, the preferred embodiment of the multi-block water level measurement method of the present invention only needs to measure the water level height by using the original image A provided by the monitoring lens 1 in conjunction with a computer system 2, regardless of the cost. The contact type or non-contact water level measuring device is greatly reduced, and the monitoring lens 1 is a conventional monitoring camera or a network camera, so that it can be set in a large amount to perform Large-scale monitoring.

In addition, the preferred embodiment of the multi-block water level measurement method of the present invention uses an image recognition method to identify the relative relationship between the water level and the surrounding scenery in an image, thereby finding the water surface position and calculating the water level height, thereby accurately measuring The water level during flooding is not affected by the color of the water and drifting water.

Furthermore, in the preferred embodiment of the multi-block water level measurement method of the present invention, a determination block R is taken out from the original image A, and a post-production image B is generated according to the determination block R, and then used for the post-production image. A gradient operator edge search method is used to perform boundary detection estimation. Compared with the case where the gradient operation sub-edge search method is directly applied to the undetermined block R, a large number of operation processes are saved, and the operation speed can be greatly improved.

In addition, in the preferred embodiment of the multi-block water level measurement method of the present invention, a plurality of determination blocks R are selected, and a plurality of water surface positions W are generated according to the plurality of determination block R operations, and the plurality of water surface positions are considered together. A water level determination result W ^{C is} generated by calculation. When a block is determined thereby reducing the shielding block by block R, so that when the operation according to the generated water W not the actual position of the flood water, can effectively reduce false determination result by W ^C W surface location of the flood level of the water The effect is such that the water level calculated according to the water level determination result W ^C has a high degree of credibility.

In the preferred embodiment of the multi-block water level measurement method of the present invention, the water level in the image can be quickly and effectively measured by analyzing and processing an image, thereby improving the flooding water level measurement efficiency, and further Achieve the effects of "reducing system installation cost", "increasing water level measurement accuracy", "upgrading operation speed" and "upgrading method reliability".

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

S1‧‧‧Image reading step

S2‧‧‧ Grayscale processing steps

S3‧‧‧ Image Enhancement Steps

S4‧‧‧Image correction procedure

S5‧‧‧Filter processing steps

S6‧‧‧ water level estimation steps

Claims (16)

A multi-block water level measurement method, in which a raw image is captured by a monitoring lens, and a computer system measures the water level of the original image, which includes the following steps: an image reading step, which is read by the computer system Entering the original image, calculating an actual size represented by a pixel according to the size of the original image; and an image correcting step, if the angle between the viewing angle of the monitoring lens and the horizon is not equal to zero, the original image is horizontally rotated according to the angle Correcting; and selecting a plurality of determination blocks from the original image; and a water level estimation step, applying a gradient operator edge search method to the determination block, and calculating image gradient values and images of each pixel of the post-image a boundary value; and estimating a boundary projection value according to the image boundary value to estimate at least one boundary position; determining a water surface position according to the boundary position, and estimating a water surface position based on the plurality of water surface positions generated by the plurality of determination blocks Water level determination result; finally, the water level determination knot is calculated from the actual size represented by the pixel of the original image The representative of the water level. The method for measuring a multi-block water level according to claim 1, wherein the method further comprises a gray scale processing step, which is performed after the image reading step is completed, and performs gray scale operation on the original image, the original The brightness of the image after gray scale operation belongs to a gray scale range. The method for measuring a multi-block water level according to claim 2, further comprising an image enhancement step, which is performed after the gray level processing step is completed, and adjusts the original image by gray scale operation to make the original image The brightness is evenly distributed between the maximum and minimum values of the gray scale range. The multi-block water level measurement method described in claim 1, 2 or 3, wherein the gradient operator edge search method calculates the image gradient and the image boundary value of each pixel of the post-image as follows Show: Where G represents the image gradient, E represents the image boundary value, f(x, y) is the grayscale value of the pixel coordinate value of the judgment block (x, y), and Gx represents the horizontal direction of the judgment block. The gradient value, Gy represents the gradient value of the vertical direction of the judgment block, and ω is a threshold value. The method for measuring a multi-block water level according to claim 4, wherein the threshold is obtained using a Canny edge detection operator. The multi-block water level measurement method as described in claim 1, 2 or 3, wherein if the image correction step selects a total of L determination blocks, and the size of the determination block is M×N pixels, Then the method of estimating the boundary projection value and estimating the boundary position is as follows: Where (x, y) represents the pixel coordinate value of the above-mentioned judging block, and I(y) represents a boundary projection value of a horizontal height in the above-mentioned judging block, and μ is a standard value. When the boundary projection value exceeds the standard value, the horizontal height coordinate is set to a boundary position. The method for measuring a multi-block water level according to claim 6, wherein the judgment block has a total of M pixels in a horizontal direction width and a total of N pixels in a vertical direction, and the standard value is M/2 pixels. . The multi-block water level measurement method described in claim 1, 2 or 3, wherein The method of determining the position of the water surface is to regard the boundary position as the water surface position. The multi-block water level measurement method according to the first, second or third aspect of the patent application, wherein the method for determining the water surface position is a boundary position of the at least one boundary position that changes with time as the water surface position. . For example, the multi-block water level measurement method described in claim 1, 2 or 3, wherein the method for calculating the water level determination result is obtained by taking the average of the plurality of water surface positions as the water level determination result. The method for measuring a multi-block water level according to claim 1, 2 or 3, wherein the method for calculating the water level determination result sets an allowable range, and the plurality of water surface positions are determined to fall within the allowable range. The average of the water surface positions is used as the water level determination result. The multi-block water level measurement method according to claim 11, wherein the allowable range is set according to the water level determination result previously measured by the multi-block water level measurement method. The multi-block water level measuring method according to claim 12, wherein the multi-block water level measuring method previously measures one water level determination result by adding an error value as the allowable range. The method for measuring a multi-block water level according to claim 12, wherein the average value of the plurality of water level determination results previously measured by the multi-block water level measurement method is added to the standard deviation and an allowable ratio. The product is taken as the allowable range. The multi-block water level measurement method as described in claim 1, 2 or 3, wherein the multi-block water level measurement method further comprises a filtering processing step, wherein a plurality of determination areas are selected in the image correction step After the block, each of the determination blocks is filtered to eliminate noise. The method for measuring a multi-block water level according to claim 15, wherein the filtering processing method used in the filtering processing step is intermediate value filtering.