TWI465721B - A method for surface velocity estimation of river water - Google Patents

Description

Method for estimating the flow rate of river surface

The invention relates to a method for estimating the flow velocity of a river surface, in particular to a method for estimating a flow velocity by using a river water image.

The velocity information on the surface of the river has a high correlation with the structure of the river bed and the water flow, that is, when the flow velocity of the river surface is fast, the river bed of the river can be judged to be shallow or have a high inclination. And under the same water flow cross section, it will also have a higher water flow rate. Therefore, the information on the velocity of the river surface is a very important reference when conducting riverbed topographic judgment or river flow estimation.

For the estimation of the flow velocity on the surface of the river, it is customary to throw a drifting object in a river channel, so that the drifting object drifts from the upstream end of the river channel to a downstream end, and the distance traveled by the drifting object and the elapsed time are counted. And divide the distance by the time to get the flow rate of the river surface. However, the drifting of the drift from the upstream end to the downstream end may be affected by the height of the river or the gravel of the river bed, causing the drifting object to hang on the river bank or the gravel group, causing the operation to be invalid and the surface of the river water cannot be accurately estimated. The flow rate.

In addition, the flow velocity estimation on the surface of the river can also be performed by placing an inductive element in the flow channel near the surface of the river to detect the flow velocity of the surface of the river. However, the sensing element senses the flow velocity of the river surface of the river at the setting, and the flow velocity can only represent the surface velocity of the river water at one of the river channels, and cannot represent the surface velocity of the river water in one section of the river channel, if desired The surface velocity of the river in one section of the channel must have multiple sensing elements in the channel. Will cause hardware costs to rise.

The main object of the present invention is to provide a method for estimating the flow rate of a river surface, which can accurately estimate the surface velocity of a river channel in a river channel region.

Another object of the present invention is to provide a method for estimating the flow rate of a river surface which has a lower hardware installation cost when performing a river surface velocity in a river region.

In order to achieve the foregoing object, the method for estimating the flow rate of the surface of the river of the present invention comprises an image ratio calculation step of reading an image data by a processor and calculating an actual length represented by a pixel according to the image data; The angle calculation step is performed by the processor, according to the actual length represented by the unit pixel, an actual length of a water surface line, a reference line and a vertical height in the image data, and the reference line and the vertical height are calculated. The actual length is substituted into an angle calculation equation to calculate an inclination angle; a water flow time calculation step is performed by the processor by substituting the inclination angle and the actual length of the vertical height into a time calculation equation to calculate a water flow time; The surface flow rate calculation step is performed by the processor dividing the actual length of the water surface line by the water flow time to obtain a surface flow rate.

The method for estimating the flow rate of the surface of the river according to the present invention, wherein the two ends of the surface line of the image data are an upstream end and a downstream end, respectively, the reference line is parallel to the horizon, and the inclination angle is formed between the reference line and the water surface line. The reference line forms the vertical height with the upstream end.

The method for estimating the flow rate of the surface of the river according to the present invention, wherein the above angle calculation equation is as follows:

Where θ is the angle of inclination, tan ^-1 (‧) is an arctangent function, h is the actual length of the vertical height H, and b is the actual length of the reference line B.

The method for estimating the flow rate of the surface of the river according to the present invention, wherein the above time calculation equation is as follows:

Where t is the water flow time, sin(‧) is a sinusoidal function, g is the gravitational acceleration value, θ is the inclination angle, and h is the actual length of the vertical height H.

The method for estimating the flow rate of the surface of the river according to the present invention, wherein the image data is captured by an image capturing device, and the image capturing device shoots the direction of the river perpendicular to the direction of the river.

1‧‧‧Image capture device

2‧‧‧ Processor

A‧‧‧ surface line

A1‧‧‧ upstream end

A2‧‧‧ downstream end

B‧‧‧ baseline

H‧‧‧Vertical height

Θ‧‧‧ tilt angle

S1‧‧‧image scale calculation step

S2‧‧‧ Tilt angle calculation step

S3‧‧‧Water flow time calculation steps

S4‧‧‧ Surface flow rate calculation steps

Figure 1 is a view of a preferred embodiment of the present invention.

Figure 2: Schematic diagram of the image data of the present invention.

Figure 3 is a flow chart showing the method for estimating the flow rate of the surface of the river according to the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; And the "downstream end" is determined by the direction in which a stream of water flows through a channel, that is, when the stream flows from the first end to the second end of the channel, the first end is the "upstream end". The second end is the "downstream end".

The "pixels" as used in the present invention refer to the smallest unit constituting an image data and can be used to indicate the resolution of the image data. For example The resolution of the image data is 1024×768, which means that the image data has a total of (1024×768=786432) pixels.

Please refer to FIG. 1 , which is a preferred embodiment of a method for estimating a flow rate of a river surface according to the present invention. The device comprises an image capturing device 1 and a processor 2 .

The image capturing device 1 is configured to capture an image of a river channel to generate an image data. The image capturing device 1 can be a device such as a general camera, a network camera, or an infrared camera.

Please refer to FIG. 2, which is a schematic diagram of the image data of the present invention. In this embodiment, the image capturing device 1 captures a shooting direction of the river channel, preferably perpendicular to the water flow direction of the river channel, so that the image data includes a water surface line A of the river channel, and the water surface line The two ends of A are an upstream end A1 and a downstream end A2, respectively. The image data further has a reference line B, and the reference line B is parallel to the horizon. In the embodiment, the reference line B is the bottom edge of the image data. An inclination angle θ is formed between the reference line B and the water surface line A, and the reference line B has a vertical height H with the upstream end A1.

The processor 2 can be a computer or any computing processor, and is electrically connected to the image capturing device 1 to receive the image data, and perform operations such as calculation and statistics according to the image data.

Referring to FIG. 3, the method for estimating the flow rate of the river surface according to the present invention comprises an image ratio calculation step S1, an inclination angle calculation step S2, a water flow time calculation step S3, and a surface flow rate calculation step S4.

In the image ratio calculation step S1, the image data is read by the processor 2, and the actual length represented by one unit pixel is calculated according to the image data.

In more detail, after the processor 2 reads the image data, the total pixel value of the image data can be obtained. Then, the processor 2 can calculate the ratio of the unit pixel of the image data to the actual scene, so as to represent the unit pixel of the image data. Length. For example, it is assumed that the image data captured by the image capturing device 1 includes the river channel. The actual length of the channel in the image data is known to be 500 cm. If the processor 2 reads the image data, the image is calculated. When the channel in the data contains 100 pixels, it can be estimated that the unit pixel represents 5 cm, that is, the ratio of the image is 5 (cm/pixel).

The tilt angle calculation step S2 is performed by the processor 2, according to the actual length represented by the unit pixel, the actual length of the water surface line A, the reference line B, and the vertical height H in the image data, and the The actual length of the reference line B and the vertical height H is substituted into an angle calculation equation to calculate the inclination angle θ .

More specifically, since the actual length represented by the unit pixel of the image data is known in the image ratio calculating step S1, the processor 1 can calculate the water surface line A for the image data. The reference line B and the vertical height H are composed of how many pixel values, and further calculate the actual length of the water surface line A, the reference line B, and the vertical height H, and then calculate the difference between the water surface line A and the reference line B. Tilt angle θ . The angle calculation equation is expressed as follows:

Where tan ^-1 (‧) is an arctangent function, h is the actual length of the vertical height H, and b is the actual length of the reference line B.

Thereby, the inclination angle θ can be calculated.

The water flow time calculation step S3 is performed by the processor 1 by substituting the inclination angle θ and the actual length of the vertical height H into a time calculation equation to calculate a water flow time.

The time calculation equation is as follows:

Where t is the water flow time, sin(‧) is a sinusoidal function, and g is the gravitational acceleration value, which is generally 9.8 (m/s ² ).

More specifically, the water flow time is the time required for the unit water amount of the river surface to pass the actual length of the vertical height H, or the unit water amount of the river surface may flow along the upstream end of the water surface line A to the downstream. The time required at the end.

The surface flow rate calculation step S4 is performed by the processor 2 by dividing the actual length of the water surface line A by the water flow time to obtain a surface flow rate.

The calculation of the surface flow rate is as follows:

Where a is the actual length of the surface line A.

Thereby, the surface flow rate can be calculated.

The method for estimating the flow rate of the surface of the river of the present invention uses an image capturing device 1 to capture the image of the channel to generate the image data. When the image data is transmitted to the processor 2, the method can be calculated by the above steps. The flow rate of the river surface.

Thereby, the invention calculates the water flow time by calculating the equation according to the actual length and the inclination angle of the river channel, and further calculates the flow velocity of the river water surface, and has the effect of accurately calculating the flow velocity.

The invention calculates the flow velocity by using the image data of the river channel, and the image data system includes a region of the river channel, so the calculated surface velocity of the river water is the average flow velocity of the entire river channel region, compared to several Inductive components are placed in the river to calculate the overall channel area The average flow rate of the present invention has the effect of reducing the cost of setting the hardware.

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 scale calculation step

S2‧‧‧ Tilt angle calculation step

S3‧‧‧Water flow time calculation steps

S4‧‧‧ Surface flow rate calculation steps

Claims (5)

A flow rate estimation method for a river surface includes: an image ratio calculation step of reading an image data by a processor and calculating an actual length represented by a unit pixel according to the image data; and an inclination angle calculation step, The processor calculates an actual length of one of the water surface line, a reference line and a vertical height in the image data according to the actual length represented by the unit pixel, and substitutes the actual length of the reference line and the vertical height into one The angle calculation equation is used to calculate an inclination angle; a water flow time calculation step is performed by the processor by substituting the inclination angle and the actual length of the vertical height into a time calculation equation to calculate a water flow time; and a surface flow rate calculation step The actual length of the water surface line is divided by the water flow time by the processor to obtain a surface flow rate. According to the flow rate estimation method of the surface of the river water according to the first aspect of the patent application, wherein the two ends of the water surface line of the image data are an upstream end and a downstream end, respectively, the reference line is parallel to the horizon, the reference line and the water surface line. The angle of inclination is formed between the reference line and the upstream end. According to the flow rate estimation method of the river surface according to item 1 of the patent application scope, the above angle calculation equation is as follows: Where θ is the angle of inclination, tan ^-1 (‧) is an arctangent function, h is the actual length of the vertical height H, and b is the actual length of the reference line B. According to the flow rate estimation method of the surface of the river water according to item 1 of the patent application scope, the above time calculation equation is as follows: Where t is the water flow time, sin(‧) is a sinusoidal function, g is the gravitational acceleration value, θ is the inclination angle, and h is the actual length of the vertical height H. According to the flow rate estimation method of the surface of the river water according to claim 1 or 2, wherein the image data is an image capturing device that captures an image of a river channel, and the image capturing device captures a shooting direction of the river channel and the river channel The direction of the water flow is vertical.