CN104408750A - Method and system for calculating proportion of seawater to land - Google Patents

Abstract

The invention relates to a method for calculating the ratio of seawater to land, which includes: drawing and cutting out a binary grayscale image of the area where the ratio of seawater to land is to be calculated according to the underlying surface of the land and seawater; Pixels of each boundary point; within the pixel range obtained by the above detection, calculate the distance from any point to the location point; use the distance from any point to the location point obtained above to calculate the area ratio of seawater to land within the Rad range. The invention also relates to a system for calculating the ratio of seawater to land. The present invention can accurately calculate the area ratio of seawater and land within the preset range of each longitude and latitude position point, and improves the current situation that the forecasting of offshore typhoon intensity is difficult at the present stage.

Description

A method and system for calculating the ratio of seawater to land

technical field

The invention relates to a method and system for calculating the ratio of seawater to land. the

Background technique

A typhoon, also known as a hurricane, is a tropical cyclone formed on a vast ocean with a tropical or subtropical sea surface temperature above 26°C. When a typhoon crosses the border, it often brings violent stormy weather, causing huge waves on the sea surface, and seriously threatening the safety of navigation. The violent wind and rain brought by the typhoon after landfall can destroy crops, various building facilities, etc., causing huge losses of people's lives and property. Therefore, timely and accurate forecasting of typhoon track, typhoon intensity, intensity and distribution of rainfall and strong winds to the public before typhoon lands is crucial to protecting life safety and reducing property losses. the

With the development of numerical models, in typhoon forecast research, typhoon track forecast is far ahead of typhoon intensity and typhoon rain distribution forecast. In terms of typhoon intensity forecasting, in the past 20 years, like the major typhoon forecasting centers in the world, my country’s typhoon intensity operational forecasting has progressed very slowly. At present, the methods widely used in operational forecasting are mainly some climate persistence methods and statistical dynamic models. Now more and more statistical methods are used to study the change of typhoon intensity, such as the Statistical Typhoon Intensity Forecast (STIPS) of the United States Joint Typhoon Warning Center, the Statistical Hurricane Intensity Forecast Model (SHIFOR) and the Statistical Hurricane Intensity Forecasting Program (SHIPS) of the National Hurricane Center At present, there is no similar research in our country. the

Factors affecting the evolution of offshore typhoon intensity include: vertical wind shear, sea surface temperature, mid-level and upper-level circulation characteristics, water vapor transport, etc. Among them, the most important is the influence of the underlying surface, because sea water is the source of typhoon power. So how to calculate the water-to-land ratio of the underlying surface, there is currently no corresponding method for reference. the

Contents of the invention

In view of this, it is necessary to provide a method and system for calculating the ratio of seawater to land. the

The present invention provides a method for calculating the ratio of seawater to land, the method comprising the following steps: a. drawing and tailoring the binary grayscale image of the area where the ratio of seawater to land is to be calculated according to the underlying surface of the land and seawater; b. detecting Obtain the pixels of each boundary point in the above-mentioned binary grayscale image; c. within the pixel range obtained by the above-mentioned detection, calculate the distance from any point to the position point; d. use the distance from any point to the position point obtained above to calculate Get the ratio of seawater to land area in the Rad range. the

Wherein, the step a includes: drawing a high-resolution two-dimensional image of the underlying surface of land and seawater according to the conditions of the underlying surface of the land and seawater; An image of the underlying surface of a land-scale area; process the clipped image of the underlying surface to obtain a binary grayscale image; read the two-dimensional matrix form of the binary grayscale image obtained through the above processing. the

The binary grayscale image is obtained by processing drawing software such as PHOTOSHOP. the

In the described step c, the distance from point A to point B is calculated as:

C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )

,

dist=R*arcos(C)

Among them, the longitude of point A is α1, and the latitude is β1; the longitude of point B is α2, and the latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R. the

The step d includes: calculating the sum S of the number of all pixels whose distance is less than the radius Rad; calculating the cumulative sum T of two-dimensional matrix values within the Rad range; calculating the ratio of T to S to obtain Rad is the ratio of seawater to land area within the radius. the

The present invention also provides a system for calculating the proportion of seawater and land, including a drawing module, a detection module and a calculation module, wherein: the drawing module is used to draw and cut out the seawater and land to be calculated according to the conditions of the underlying surface of the land and seawater The binary grayscale image of the proportional area; the detection module is used to detect the pixels of each boundary point in the above binary grayscale image; the calculation module is used to calculate any point to The distance of the location point; the calculation module is also used to calculate the area ratio of seawater to land within the range of Rad by using the distance from any point to the location point obtained above. the

Wherein, the drawing module is specifically used for: drawing a high-resolution two-dimensional underlying surface image of land and sea water according to the conditions of the underlying surface of land and sea; The image of the underlying surface of the area with a proportion of seawater and land; process the clipped image of the underlying surface to obtain a binary grayscale image; read the two-dimensional matrix form of the binary grayscale image obtained through the above processing. the

The binary grayscale image is obtained by processing drawing software such as PHOTOSHOP. the

The calculation module calculates the distance from point A to point B as:

C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )

,

dist=R*arcos(C)

Among them, the longitude of point A is α1, and the latitude is β1; the longitude of point B is α2, and the latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R. the

The calculation module is specifically used for: calculating the sum S of the number of pixels within the range of all distances less than the radius Rad; calculating the cumulative sum T of two-dimensional matrix values within the range of Rad; calculating the ratio of T to S to obtain Ratio of seawater to land area within a radius of Rad. the

The present invention is a method and system for calculating the proportion of seawater and land, which can accurately calculate the area ratio of seawater and land within the preset range of each longitude and latitude position point, and analyze and predict the impact of seawater area and seawater temperature on typhoon intensity when a typhoon lands offshore. To improve the current situation that it is very difficult to forecast the intensity of offshore typhoons. the

Description of drawings

Fig. 1 is a kind of flow chart of the method for calculating seawater land ratio of the present invention;

FIG. 2 is a hardware architecture diagram of a system for calculating the ratio of seawater to land according to the present invention. the

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. the

Referring to Fig. 1, it is a flow chart of the operation of a preferred embodiment of the method for calculating the proportion of seawater and land in the present invention. the

In this embodiment, the image of the underlying surface in South China is taken as an example for illustration:

Step S401, according to the conditions of the underlying surface of land and sea in the northern hemisphere, draw and cut out a binary grayscale image of South China. details as follows:

The first step is to draw a high-resolution two-dimensional image of the land of Southeast Asia in the northern hemisphere and the underlying surface of the Pacific Ocean according to the conditions of the underlying surface of Southeast Asia in the northern hemisphere and the Pacific Ocean. the

In the second step, the image of the underlying surface in South China is obtained by cropping the two-dimensional underlying surface image drawn above. Since the latitude range of South China is 1-52 degrees and the longitude range is 98-153 degrees, this embodiment cuts out the underlying surface image with the latitude range of 1-52 degrees and the longitude range of 98-153 degrees. the

The third step is to process the cropped image of the underlying surface to obtain a binary grayscale image. Specifically: In this embodiment, the cropped image of the underlying surface is processed into a binary grayscale image by drawing software. Described drawing software comprises: the drawing software of PHOTOSHOP and Windows system. the

The fourth step is to read the binary grayscale image obtained by the above processing. Specifically: the result of reading the binary grayscale image in this embodiment is in the form of a two-dimensional matrix, where "1" represents land and "0" represents ocean. the

Step S402, detecting and obtaining the pixels of each boundary point in the above-mentioned binary grayscale image, so that the pixel point range corresponds to the latitude and longitude range one by one. in particular:

The present embodiment uses the drawing software of Windows system, detects and obtains the pixel of each boundary point in the above-mentioned binary gray scale image, realizes traversing the range of this pixel value by program code, makes it one-to-one correspondence with latitude and longitude range. the

Step S403, within the pixel range obtained by the above detection, calculate the distance from any point to the position point. in particular:

This embodiment uses the following method to obtain the distance between any two points on the sphere:

Assume that the longitude of point A is α1 and latitude is β1; the longitude of point B is α2 and latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R (Km). At the same time, it is agreed that east longitude is positive and west longitude is negative; north latitude is positive and south latitude is negative. Then the distance from point A to point B is:

C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )

Formula 1)

dist=R*arcos(C)

Step S404, using the above obtained distance from any point to the location point, to calculate the area ratio of seawater to land within the range of Rad. details as follows:

In this embodiment, the sum S of the number of pixels whose dist is less than the radius Rad can be calculated by formula (1) by comparison, and then the two-dimensional matrix is obtained by step S401, and the two-dimensional matrix in the Rad range is calculated. The sum T of value accumulation, the ratio of T and S can be calculated to obtain the area ratio of seawater and land within the radius of Rad at the position point. the

Referring to FIG. 2 , it is a hardware architecture diagram of a system for calculating the ratio of seawater to land according to the present invention. The system includes a drawing module, a detection module and a calculation module. the

In this embodiment, the image of the underlying surface in South China is taken as an example for illustration:

The drawing module is used to draw and cut out the binary grayscale image of South China according to the underlying surface of land and sea in the northern hemisphere. details as follows:

The first step is to draw a high-resolution two-dimensional image of the land of Southeast Asia in the northern hemisphere and the underlying surface of the Pacific Ocean according to the conditions of the underlying surface of Southeast Asia in the northern hemisphere and the Pacific Ocean. the

In the second step, the image of the underlying surface in South China is obtained by cropping the two-dimensional underlying surface image drawn above. Since the latitude range of South China is 1-52 degrees and the longitude range is 98-153 degrees, this embodiment cuts out the underlying surface image with the latitude range of 1-52 degrees and the longitude range of 98-153 degrees. the

The third step is to process the clipped image of the underlying surface through drawing software to obtain a binary grayscale image. Specifically: In this embodiment, the cropped image of the underlying surface is processed into a binary grayscale image by drawing software. Described drawing software comprises: the drawing software of PHOTOSHOP and Windows system. the

The fourth step is to read the binary grayscale image obtained by the above processing. Specifically: the result of reading the binary grayscale image in this embodiment is in the form of a two-dimensional matrix, where "1" represents land and "0" represents ocean. the

The detection module is used to detect the pixels of each boundary point in the above-mentioned binary grayscale image, so that the pixel point range corresponds to the latitude and longitude range one by one. in particular:

This embodiment uses the drawing software of the Windows system to detect the pixels of each boundary point in the above-mentioned binary grayscale image, and realizes traversing the range of the pixel value through the program code, so that it corresponds to the latitude and longitude range one by one. the

The calculation module is used to calculate the distance from any point to the position point within the detected pixel range. in particular:

This embodiment uses the following method to obtain the distance between any two points on the sphere:

Assume that the longitude of point A is α1 and latitude is β1; the longitude of point B is α2 and latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R (Km). At the same time, it is agreed that east longitude is positive and west longitude is negative; north latitude is positive and south latitude is negative. Then the distance from point A to point B is:

C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )

Formula 1)

dist=R*arcos(C)

The calculation module is also used to calculate the area ratio of seawater to land within the range of Rad by using the distance from any point obtained above to the location point. details as follows:

In this embodiment, the sum S of the number of pixels whose dist is less than the radius Rad can be calculated by formula (1) by comparison, and then the two-dimensional matrix is obtained by step S401, and the two-dimensional matrix in the Rad range is calculated. The sum T of value accumulation, the ratio of T and S can be calculated to obtain the area ratio of seawater and land within the radius range of Rad at the position point. the

The present invention has been effectively tested at various latitude and longitude locations, and found through comparison of actual conditions that the present invention can accurately calculate the area ratio of seawater and land at each location. the

Although the present invention has been described with reference to the current preferred embodiments, those skilled in the art should understand that the above-mentioned preferred embodiments are only used to illustrate the present invention, and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and scope of principles shall be included in the protection scope of the present invention. the

Claims (10)

1. A method for calculating seawater and land ratios, characterized in that the method may further comprise the steps: a. According to the underlying surface of land and sea water, draw and cut out the binary grayscale image of the area where the ratio of sea water to land is to be calculated; b. Detecting the pixels of each boundary point in the binary grayscale image; c. Within the range of pixels detected above, calculate the distance from any point to the position point; d. Using the distance from any point obtained above to the location point, calculate the area ratio of seawater to land within the Rad range. 2. method as claimed in claim 1, is characterized in that, described step a comprises: Draw high-resolution two-dimensional images of land and seawater underlying surfaces according to the conditions of land and seawater underlying surfaces; From the two-dimensional underlying surface image drawn above, crop the underlying surface image of the area where the proportion of seawater and land is to be calculated; Processing the image of the underlying surface cut out above to obtain a binary grayscale image; Read the two-dimensional matrix form of the binary grayscale image obtained from the above processing. 3. The method according to claim 2, wherein the binary grayscale image is obtained by processing drawing software such as PHOTOSHOP. 4. the method for claim 1 is characterized in that, in the described step c, calculate the distance from point A to point B as: C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )                           dist=R*arcos(C) Among them, the longitude of point A is α1, and the latitude is β1; the longitude of point B is α2, and the latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R. 5. method as claimed in claim 1, is characterized in that, described step d comprises: Calculate the sum S of the number of all pixels whose distance is less than the radius Rad; Calculate the cumulative sum T of the two-dimensional matrix values within the Rad range; Calculate the ratio of T to S to obtain the ratio of the area of seawater to land within the radius of Rad. 6. A system for calculating the proportion of seawater and land, characterized in that the system includes a drawing module, a detection module and a calculation module, wherein: The drawing module is used to draw and cut out the binary grayscale image of the area where the proportion of seawater and land is to be calculated according to the underlying surface of land and seawater; The detection module is used to detect the pixels of each boundary point in the binary grayscale image; The calculation module is used to calculate the distance from any point to the position point within the range of pixels detected above; The calculation module is also used to calculate the area ratio of seawater to land within the range of Rad by using the distance from any point obtained above to the location point. 7. The system according to claim 6, wherein the drawing module is specifically used for: Draw high-resolution two-dimensional images of land and seawater underlying surfaces according to the conditions of land and seawater underlying surfaces; From the two-dimensional underlying surface image drawn above, crop the underlying surface image of the area where the proportion of seawater and land is to be calculated; Processing the image of the underlying surface cut out above to obtain a binary grayscale image; Read the two-dimensional matrix form of the binary grayscale image obtained from the above processing. 8. The system according to claim 7, wherein the binary grayscale image is obtained by processing drawing software such as PHOTOSHOP. 9. The system according to claim 6, wherein the calculation module calculates the distance from point A to point B as: C＝sin(β ₁ )*sin(β ₂ )+cos(β ₁ )*cos(β ₂ )*cos(α ₁ -α ₂ )                       dist=R*arcos(C) Among them, the longitude of point A is α1, and the latitude is β1; the longitude of point B is α2, and the latitude is β2, where α1, α2, β1, and β2 are all radians, and the radius of the earth is R. 10. The system according to claim 6, wherein the calculation module is specifically used for: Calculate the sum S of the number of all pixels whose distance is less than the radius Rad; Calculate the cumulative sum T of the two-dimensional matrix values within the Rad range; Calculate the ratio of T to S to obtain the ratio of the area of seawater to land within the radius of Rad.