KR101448223B1 - A System and method for flood detection using satellite observation, and Record media recorded program for realizing the same method - Google Patents

Abstract

The present invention relates to a method and system for implementing information on flooding caused by floods from observations of satellites, comprising an observation sensor unit mounted on an artificial satellite for sensing the surface reflectance of each spectral channel in an observation target area, A flood detection decision unit for determining a flood area through new color synthesis based on the value of the surface reflectance for each spectral channel, Based flood detection system including a flood detection and verification unit that verifies the flood area.

Description

TECHNICAL FIELD [0001] The present invention relates to a flood detection system, a flood detection system, a flood detection method, and a program for realizing a flood detection method,

The present invention relates to a method and system for implementing information on flooding due to floods from observations of satellites.

Recently, the incidence of natural disasters is increasing, and the intensity of the disasters is also increasing. The resulting flood-like disasters repeatedly cause massive tremendous human and economic losses throughout the world. Accurate and rapid detection of such disasters provides crucial information for pre-disaster prevention and recovery after loss. can do. Satellite observation is a very useful tool because it is hard to observe and observe on the ground in real time near the wide range of large rivers.

Therefore, flood detection and surveillance research using satellites has been conducted in many countries. In the background, there is a contrast in reflectivity due to the difference in physical properties of water and soil. Therefore, most countries have been using the Visible and Near Infrared spectroscopy information of sensors mounted on satellites such as MODIS, LandSat and AVHRR for flood detection.

However, most of the satellite-based flood detection techniques are based on True Color, which is a combination of spectral channels corresponding to the red-green-blue color similar to that observed by human eyes. ) Images. However, this method is advantageous for detecting highly reflective objects such as clouds, but it is difficult to analyze because the flood area is not clearly visible on the image.

Korean Patent Laid-Open Publication No. 10-2010-0131902 Korean Patent Registration No. 10-1087754

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide an image processing apparatus and method, A new satellite - based flood detection method that can generate information on flooding is proposed.

As a means for solving the above-mentioned problems, the present invention provides a method and system for calculating flood and flood information by combining a new color composite image method and polarizing properties of an electromagnetic wave based on satellite data.

The system according to the present invention first presents a new color composite image combination based on the input data of the unipolarized reflectance of the observed object observed by the satellite and uses the surface reflectance of the observed object as the verification method It is composed of parts that determine whether the soil is dry, strong, or flooded by calculating the index of refraction of the material after it has been decomposed into reflectance by vertical and horizontal polarization channels.

More specifically, the present invention relates to a method of detecting a flood area by combining a new color based on an observation sensor unit mounted on an artificial satellite that senses the surface reflectance of each spectral channel in an observation target area and a surface reflectance of each spectral channel sensed by the observation sensor unit, Based flood detection system including a detection determination unit and a flood area detection verification unit that verifies the flood area determined by the flood detection determination unit using the polarization different sign and the refraction index of the observation target area.

According to the present invention, it is possible to provide information on floods on a semi-real time basis with very accurate accuracy based on satellite observations. Therefore, it can be used effectively in the event of a disaster such as flood, and it can provide very important industrial and economic information for pre-disaster prevention and recovery after loss.

For example, by detecting and monitoring the areas before and after flooding, it is possible to provide policy makers with important guidelines for determining damages. Therefore, it is expected to contribute to national disaster effectively.

1 is a schematic block diagram showing a flood detection system according to the present invention.
2 is a block diagram illustrating a method for detecting flood and flood information using a system in accordance with the present invention.
Figure 3 is an example of flood detection using a satellite MODIS sensor.
4 is a conceptual diagram showing color synthesis of visible light and light.
FIG. 5 is an example of MODIS True color, which shows an image of yellow dust passing over the Korean peninsula.
FIG. 6 is a graph showing the degree of reflectivity of various materials depending on the MODIS channel (wavelength band).
FIG. 7 shows the verification result of the flood zone according to the present invention.
FIG. 8 shows an example of a software implementation of the flood detection system according to the present invention.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The present invention is based on the observation of the surface reflectance of each spectral channel from visible to infrared rays, and selects the channels that strongly respond to water and soil, Green (G), and blue (B) color tables), and the area of the area due to the flood is calculated by giving a constant boundary value to the flood area in comparison with the surrounding soil. The present invention also relates to a technique for detecting a flood and flood area based on a satellite, which verifies whether the refractive index value, which is a characteristic of a material, is reflected by the reflectance decomposition and which corresponds to the refractive index value of water and soil in the observation spectral region.

FIG. 1 illustrates a flood detection system in accordance with the present invention, and FIG. 2 is a block diagram illustrating a method for detecting flood information using a system according to the present invention.

1 and 2, a satellite-based flood detection system according to the present invention includes an observation sensor unit 100 mounted on a satellite for sensing the surface reflectance of each spectral channel in an observation target area, 100), a flood detection determination unit (200) for determining a flood area based on the value of the surface reflectance of each spectral channel sensed by the flood detection unit (100) And a flood detection verifying unit 300 for verifying using the apostrophe and the refraction index.

The observation sensor unit 100 includes an observation module including an observation sensor of a satellite. Here, the low-orbit satellite data of the United States called AQUA is used as an example. This is a very common satellite for observing the earth. MODIS Sensor (Moderate Resolution Imaging Spectroradiometer) is very dense with a spatial resolution of 250m ~ 1km. In addition, most of the observation sensors use visible or near infrared sensors and are mounted on various satellites such as low orbit and stationary orbit. The sensor MODIS observation data of Aqua satellite which is low earth orbit satellite is widely used worldwide. There are 36 spectral channels such as 0.47 ㎛, 0.56 ㎛, 0.65 ㎛, 0.86 ㎛, 1.24 ㎛, 1.64 ㎛ and 2.13 ㎛ for the observation channels, but not all channels are suitable for flood detection. As an example of a practical application of the present invention, we have selected the case of flooding occurring on the Fitzroy River in western Australia on March 7, When the results of the present invention were applied, it can be seen that a total area of 2,231 km ² was overflowed (see FIG. 3 (d)).

The flood area detection determination unit 200 forms a new average reflectivity by combining the values of the surface reflectance values of the spectral channels sensed by the observation sensor unit, and determines a flood area through new color synthesis.

Specifically, the flood detection determination unit 200 according to an exemplary embodiment of the present invention determines the color by using red, green, and blue based on the surface reflectance of each of the three observation channels transmitted from the observation sensor unit. And a flood area determining unit 220 for determining a flood area based on a reflectivity boundary value for each spectral channel.

Particularly, the new color synthesizing unit 320 of the flood detection determining unit 200 according to the present invention converts the reflectance observed in each channel (wavelength band) of each sensor of the observation sensor unit mounted on the satellite into the light 3 The color synthesis method for synthesizing the three colors is used in correspondence with the primary colors such as red, green and blue.

That is, in the present invention, a method of replacing using the same natural color (True Color) as that observed with human eyes using a wavelength band corresponding to three primary colors of light is proposed. More specifically, in the present invention, a new color synthesis method is proposed in which, instead of the wavelength band corresponding to the three primary colors of light, three elements of observations of other wavelength band such as near infrared are corresponded to the three primary colors of light. The boundary value is applied.

For this purpose, the new color synthesizing unit 210 converts the three surface reflectances into Red, Green, and Blue colors according to the following expression (1). After that, three primary colors of light are synthesized. FIG. 4 shows an example of color synthesis of the visible light and the light.

The following {Table 1} is a table summarizing the observable channels (wavelength band) of MODIS sensors mounted on satellites.

{Table 1}

Therefore, by combining MODIS channels 3, 4, and 1, it is possible to synthesize the same natural color (True Color) as that seen by humans. FIG. 5 is an example of MODIS True color, which is observed on March 22, 2008, when yellow dust passing over the Korean peninsula is observed.

The new RGB synthesis technique according to the present invention will be described in detail. This is accomplished by converting the reflectance values of three channels in the visible and near infrared channels into red (R), green (G) and blue (B) (Such as a difference between channels or an average) are expressed in red, green, and blue, respectively. This function is mathematically defined by a decimal notation or a hexadecimal notation in RGB color combination of red (R), green (G), and blue (B).

These RGB colors can be applied to satellite image analysis and digital image processing. To create a channel-specific image, the observed reflectance value (0 to 1) is converted to a color value of 8 bits (0 to 255). The 8-bit image of the three channels has a maximum range of 16,777,216 colors. Therefore, if the transformed RGB is taken as each axis of the three-dimensional space, then the color of black (0,0,0), red (255,0,0), green (0,255,0), blue (0,0,255) (255,255,0), magenta (255,0,255), cyan (0,255,255), and white (255,255,255). The RGB conversion equation is as follows.

{1}

(Where C represents the color value selected from among the RGB colors), {represents the position of the 3D color space, n represents the color value that can be represented for each channel, and is a total of 8 bits. It means color index.)

For example, the wavelength of light 0.47 탆 corresponds to the blue light of visible light. The wavelength of 0.65 ㎛ corresponds to the red light of visible light, and vegetation absorbs red light, which is useful for distinguishing between vegetation and soil. The wavelength of 0.56 mu m corresponds to the green of the visible ray.

Therefore, when the reflectance observed at each wavelength is made to correspond to the color composition combination R (0.65 占 퐉) - (0.47 占 퐉) -B (0.56 占 퐉), it appears to be the same as the color seen by human eyes Reference). While these natural colors are useful in a wide variety of applications, they are not as powerful as flood detection.

FIG. 6 shows the degree of reflectivity of Clay, Sand, Grass, Snow, Water, etc. according to the MODIS channel (wavelength band) Which was developed by using the spectral data provided by.

Therefore, since the new color synthesis according to the present invention can select three of the MODIS channels, a very wide variety of combinations are possible. Through various combinations of experiments, the present invention suggests a method of replacing 0.47 占 퐉 with a reflectance observed at a wavelength of 0.86 占 퐉, which exhibits a strong absorbency against water. This is because, when the new color synthesis method R (0.56 탆) -G (0.86 탆) -B (0.66 탆) is applied, a strong contrast is generated in the flood area (see FIG.

The average reflectivity observed in the three spectral channels of the observational sensor part of the satellite is shown in Fig. 3 (c).

In order to determine the flood area, the reflectance boundary value per spectral channel is defined as follows. That is, in order to determine the flood area, the flood area determining unit 230 according to the present invention uses the boundary value R of the reflectance per spectral channel as {equation 2}.

{Equation 2}

0.094? R (0.56 占 퐉)? 0.14, (R (0.56 占 퐉) reflectance at 0.56 占 퐉 wavelength)

0.004? R (0.86 占 퐉)? 0.12, (R (0.86 占 퐉 reflectance at 0.86 占 퐉 wavelength)

0.1? R (0.66 占 퐉)? 0.66, (R (0.66 占 퐉) reflectance at 0.66 占 퐉 wavelength)

In addition, the flood detection verification unit 130 of the present invention may calculate vertical and horizontal polarized reflectivity and index of refraction using the reflectivity transmitted from the observation sensor unit 100, and verify whether the reflected light is in a physically valid range Function.

For this, the flood area detection and verification unit according to the present invention includes a vertical and horizontal polarization calculation unit 310 for decomposing and calculating the vertical and horizontal polarization reflectances of the spectral channels sensed by the observation sensor unit, A refraction index calculating unit 320 for calculating an index of refraction of a flood area, which is an observation target area, using the vertical polarization reflectivity and the horizontal polarization reflectivity according to the following equation 5, And a verification comparator 330 for verifying and comparing the flood area provided by the decision unit.

Specifically, the vertical and horizontal polarization calculator 310 can determine the vertical polarization reflectivity and the horizontal polarization reflectivity of the surface reflectance by the following {Expression 3} and {Expression 4}.

{Equation 3}

{Expression 4}

(Where R (θ) represents the surface reflectance before polarization, R _V represents the vertical polarization reflectivity, R _H represents the horizontal polarization reflectivity, and θ represents the zenith angle of the satellite).

Of course, the vertical and horizontal polarization calculation unit 310 may be implemented by decomposing the surface reflectance of each of the three spectral channels sensed by the observation sensor unit into vertical and horizontal polarized light reflectances. However, The surface reflectance of each channel may be combined and decomposed into vertical and horizontal polarized reflectance for the average reflectivity on the basis of the average reflectivity.

Then, the refractive index calculating unit 320 calculates the refractive index of the flood area using the vertical polarized light reflectance or the horizontal polarized light reflectance provided by the {Expression 3} and {Expression 4} Thereby calculating the refractive index of the flood area.

{Eq. 5}

Thereafter, the verification comparator 330 verifies and compares the flood area proposed by the flood area detection and determination unit based on the refraction index value of the flood area.

The image shown in FIG. 4 shows the result of applying the system according to the present invention described above.

Referring to the image of FIG. 4, the real part of the refractive index, which is a complex number of dry silica, calcite and soil, is 1.48, 1.60, 1.4 and so on in the visible ray region, and the real part of the refractive index of water is 1.33 In the above, it can be seen that the calculated refractive index value physically appears well within the range of soil and water.

As described above, according to the present invention, the satellite-based flood detection locality method including the observation sensor unit, the flood detection decision unit, and the flood detection verification unit and the flood detection system described above can be implemented through software. Therefore, it is needless to say that the system and method according to the present invention can be manufactured in the form of a computer-readable recording medium having a software configuration and a program for executing the system.

FIG. 5 shows an example of software implementation of the flood detection system according to the present invention.

Particularly, the term " part " used in this embodiment of the flood detection system according to the present invention means a hardware component such as software or an FPGA or an ASIC, and 'part' performs certain roles. However, 'part' is not meant to be limited to software or hardware. &Quot; to " may be configured to reside on an addressable storage medium and may be configured to play one or more processors. Thus, by way of example, 'parts' may refer to components such as software components, object-oriented software components, class components and task components, and processes, functions, , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and components may be further combined with a smaller number of components and components or further components and components. In addition, the components and components may be implemented to play back one or more CPUs in a device or a secure multimedia card.

According to the present invention, it is possible to detect and monitor flood through satellite observation, and the information can be utilized in industrial economics such as national disaster prevention work and restoration such as disaster disaster prevention and post-treatment measures in quasi-real-time.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

100: observation sensor unit
200: Flood detection determination unit
210: New color synthesizing unit
220: Flood area determining unit
300: flood detection verification unit
310: Vertical and horizontal polarization calculation unit
320: refractive index calculating section
330:

Claims (8)

An observation sensor unit mounted on an artificial satellite which senses the surface reflectance of each spectral channel in an observation target area;
A flood detection determining unit for determining a flood area through new color synthesis based on the value of the surface reflectance of each spectral channel sensed by the observation sensor unit;
A flood detection verification unit that verifies the flood area determined by the flood detection determination unit using the polarization different sign and the refraction index of the observation target area;
Based flood detection system.
The method according to claim 1,
The flood detection determination unit determines,
A new color synthesizing unit that combines the surface reflectance of each of the three observation channels transmitted from the observation sensor unit or expresses colors in red, green, and blue on the basis of the transmitted surface reflectance; And
A flood region determining unit for determining a flood region based on a reflectivity boundary value per spectral channel;
Based flood detection system.
The method of claim 2,
Wherein the new-
A satellite-based flood detection system that uses a new color synthesis method that converts the above three surface reflectances into red, green, and blue colors by the following {expression 1}.
{1}
C _i = { r _i , g _i , b _i }, 0 = i <2 ⁿ
(Where C _i is the color value selected from the entire RGB colors, {} is the position of the three-dimensional color space, n is the color value that can be displayed for each channel, ) &Lt; / RTI &
The method of claim 3,
Wherein the flood-
Wherein a reflection boundary value (R) for each spectral channel is defined by the following expression (2) to determine a flood area.
{Equation 2}
0.094? R (0.56 占 퐉)? 0.14, (R (0.56 占 퐉) reflectance at 0.56 占 퐉 wavelength)
0.004? R (0.86 mu m)? 0.12, (R (0.86 mu m reflectance at a wavelength of 0.86 mu m)
0.1? R (0.66 占 퐉)? 0.66, (R (0.66 占 퐉) reflectance at a wavelength of 0.66 占 퐉)
5. The method according to any one of claims 1 to 4,
The flood detection &
A vertical and horizontal polarization calculation unit for decomposing the surface reflectance of each spectral channel sensed by the observation sensor unit into vertical polarization reflectance and horizontal polarization reflectance by the following {Expression 3} and {Expression 4};
A refractive index calculating unit for calculating a refractive index of the flood area as an observation target area by using the vertical polarization reflectivity and the horizontal polarization reflectivity;
A verification comparator for verifying and comparing the flood area proposed by the flood area detection decision unit on the basis of the refraction index value of the flood area;
Based flood detection system.
{Equation 3}

{Expression 4}

(Where R (θ) represents the surface reflectance before polarization, R _V is the vertical polarization reflectivity, R _H is the horizontal polarization reflectivity, and θ is the zenith angle of the satellite).
{Eq. 5}

The method of claim 5,
Wherein the vertical and horizontal polarization calculators comprise:
The average reflectivity is calculated by combining the surface reflectivities of the three spectral channels sensed by the observation sensor unit, and the average reflectivities are calculated based on the average reflectivities by the {3} and {4} Based flood detection system.
Measuring the surface reflectance of an observation target area sensed by an observation sensor of the satellite;
Combining the surface reflectance of each spectral channel transmitted from the observation sensor and converting the red, green, and blue colors into new colors through a new color synthesis method according to the following formula 1;
Determining a flood area by comparing the target area expressed by the color with a boundary value (R) of the reflectance of each spectral channel according to the following equation (2);
The index reflectance of each spectral channel sensed by the observation sensor is decomposed into the vertical polarization reflectance and the horizontal polarization reflectivity, and the refractive index of the flood area, which is the observation target area, is calculated by the following equation 5 using the vertical polarization reflectivity and the horizontal polarization reflectivity Verifying the flood zone;
Based flood detection method.
{1}
C _i = { r _i , g _i , b _i }, 0 = i <2 ⁿ
(Where C _i is the color value selected from the entire RGB colors, {} is the position of the three-dimensional color space, n is the color value that can be displayed for each channel, ) &Lt; / RTI &

{Equation 2}
0.094? R (0.56 占 퐉)? 0.14, (R (0.56 占 퐉) reflectance at 0.56 占 퐉 wavelength)
0.004? R (0.86 mu m)? 0.12, (R (0.86 mu m reflectance at a wavelength of 0.86 mu m)
0.1? R (0.66 占 퐉)? 0.66, (R (0.66 占 퐉) reflectance at a wavelength of 0.66 占 퐉)

{Eq. 5}

A computer-readable recording medium containing the program for performing the satellite-based flood detection method of claim 7.

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