KR101691476B1 - Heat transfer equation solving and infrared radiation calculation method and apparatus for 3D structure by interpolation of normal vector - Google Patents

Abstract

The present invention relates to an infrared image technology, and more particularly, to a temperature and infrared signal calculation method and apparatus for performing a faster calculation by solving a heat transfer equation and calculating an infrared signal in order to simulate an infrared image of a three- It is about.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for calculating a temperature-infrared signal of a three-dimensional shape by direction vector interpolation,

The present invention relates to an infrared image technology, and more particularly, to a temperature-infrared signal calculation method apparatus for solving a heat transfer equation and simulating an infrared signal in order to simulate a three-dimensional infrared image, will be.

Infrared signals emitted or reflected from military platforms (traps, tanks, airplanes, etc.) are equipped with deceptive devices such as flare and devices for reducing infrared signals, since they are the main sources of detection of the threat weapon system.

However, in order to analyze the signal level and the deception effect of the platform in various environments, the infrared signal is affected by the weather environment and the signal level changes widely. Therefore, .

A general procedure for generating a three-dimensional infrared image is briefly described below. Referring to FIG. 1, first, a three-dimensional CAD model of a shape is input and material and surface characteristics of each part are set and finely divided into a triangle or a square plane to form a shape like a mesh (S110, S120).

The temperature of the vertex can be obtained by solving the heat transfer equation using the position and direction vector (Normal Vector) of each vertex forming the net (S130). The infrared signal radiated by the temperature of the apex and the infrared signal received by an external heat source such as the sun are added to obtain the infrared signal of the apex (S140). The infrared signal values of the vertexes are mapped to a monochrome or color table and displayed on a computer screen (S150, S160).

However, large military platforms typically use hundreds of thousands to millions of vertices. Therefore, there is a problem in that it takes much time to solve the complex formula for calculating the temperature and / or the infrared signal for each vertex repeatedly.

1. Korean Published Patent No. 10-2012-0083891 2. Korean Patent Publication No. 10-2011-0040402 3. Korean Patent Publication No. 10-2008-0045175

1. Yoon Sik Kim et al., "Oceanographic and Numerical Analysis of Trap Infrared Signals", Shipbuilding Marine Technology No. 50 (December 2010) pp.13-20.

The present invention has been proposed in order to solve the problem according to the above background art, and it is an object of the present invention to provide a temperature and infrared signal calculation method which is performed at a higher speed by solving a heat transfer equation and calculating an infrared signal in order to simulate a three- The purpose is to provide.

The present invention provides a temperature and infrared signal calculation method that solves a heat transfer equation and simulates an infrared signal in order to simulate an infrared image of a three-dimensional shape in order to accomplish the above-mentioned problems.

The temperature and infrared signal calculation method includes:

A mesh dividing step of setting the material and surface characteristics of each part of the three-dimensional CAD model of the shape and dividing the data into a mesh shape;

A two-dimensional infrared image generating step of generating a two-dimensional infrared image by interpolating a position and a direction vector of each vertex in a mesh shape to define a direction vector of the pixel;

An infrared signal value calculation step of calculating a temperature for a direction vector of a defined pixel and calculating an infrared signal value using the calculated temperature; And

And mapping the calculated infrared signal value to the color of the pixel to generate an infrared image.

At this time, the calculation of the temperature and the infrared signal value is performed using Equation

: 대기온도, T₀: 구하고자하는 표면 온도, σ: 스테판-볼츠만 상수(Stefan-Bolzman constant), T_surr: 대기복사 겉보기 온도, k: 열전도도(thermal conductance), T₁: 1차원 열전도에서 인접 구간의 온도,

: 1차원 열전도에서 구간의 간격,

: 열발생율,

: 흡수율, G_D: 직달 태양복사, G_d: 확산 태양복사, θ: 직달 태양복사의 입사각을 나타낸다)을 이용하여 이루어지는 것을 특징으로 할 수 있다.(Where h: convection coefficient, A: surface area,

: T _{0 is} the surface temperature to be obtained, σ is the Stefan-Bolzman constant, T _{surr is the} atmospheric radiation apparent temperature, k is the thermal conductance, T _{1 is the} one dimensional heat conduction, The temperature of the adjacent section,

: Interval of interval in one dimensional heat conduction,

: Heat generation rate,

: Absorptivity, G _D : direct solar radiation, G _d : diffuse solar radiation, and θ: incidence angle of direct solar radiation).

The color of the pixel may be a gray color or a color color.

In addition, the temperature calculation may be a one-dimensional steady state thermal conduction.

Further, the incident angle of the direct sun radiation may be an angle between the direction vector of the pixel and the direction of the incident sun.

Also, the solar radiation is divided into direct radiation and diffuse radiation, and direct radiation can be characterized by being different depending on the angle of incidence on the surface.

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Further, the division may be characterized by dividing the three-dimensional CAD model of the shape into a triangular or rectangular plane.

On the other hand, another embodiment of the present invention includes an input for assigning a material and a surface property to each part and inputting a three-dimensional CAD model of the shape into a mesh A processor; A two-dimensional infrared image is generated by interpolating a position and a direction vector of each vertex in the form of a mesh to define a direction vector of the pixel, and a temperature is calculated for a direction vector of the defined pixel A calculation unit for calculating an infrared signal value using the calculated temperature; And an output unit for mapping the calculated infrared signal value to the color of the pixel and generating an infrared image. The present invention provides an apparatus for calculating a temperature-infrared signal of a three-dimensional shape by direction vector interpolation.

According to the present invention, it is possible to increase the operation speed of the program by about 10 to 1000 times by calculating the temperature and the infrared signal for each pixel without performing temperature and infrared signal calculation for each vertex in order to generate an infrared image of the platform.

As another effect of the present invention, it is possible to utilize the infrared signal level and / or deception effect of the platform in various environments to verify and construct data.

FIG. 1 is a flowchart showing a general procedure for generating a general three-dimensional infrared image.
2 is a flowchart illustrating a procedure for generating an infrared image according to an exemplary embodiment of the present invention.
3 is a configuration diagram of an infrared signal calculation apparatus 300 for generating an infrared image according to an embodiment of the present invention.
4 is a conceptual diagram for calculating incident energy by interpolation of a direction vector according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

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.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for calculating a three-dimensional temperature-infrared signal by direction vector interpolation according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The final output of the infrared image generating program is a two-dimensional image appearing on a computer screen (or buffer) according to the spatial position, the angle of view and resolution of the infrared sensor.

The resolution of a military infrared sensor is generally about 320x256 pixels x 1024x768 pixels. This is about 80,000 pixels and 800,000 pixels in terms of the number of pixels. Considering the angle of view of the infrared sensor, the object appears only in a few pixels at a distance, and the rest appears as a background.

In addition, military infrared sensors look at objects in only one direction, so they are more than half invisible. Therefore, in one embodiment of the present invention, instead of the heat transfer and / or infrared signal calculation performed on the vertices, a method of calculating only the pixels to be displayed on the screen is selected.

In addition, typically, temperature and infrared signal calculations are performed for each vertex and the calculated infrared signal value is mapped to the vertex color. Then, in the process of converting into the two-dimensional image of the screen, the color of the vertices constituting the pixel is interpolated.

In one embodiment of the present invention, first, in the process of converting a 2D image into a 2D image, a direction vector of a vertex is interpolated to define a direction vector of the pixel, and a temperature and infrared signal calculation is performed on the direction vector of the pixel, Maps the value to the color of the pixel. This concept is shown in Fig. 2 in an easy to understand manner.

2 is a flowchart illustrating a procedure for generating an infrared image according to an exemplary embodiment of the present invention. Referring to FIG. 2, first, a three-dimensional CAD model of a shape is input and material and surface characteristics of each part are set and finely divided into a triangle or a square plane to form a shape like a mesh (S210, S220).

A two-dimensional infrared image is generated using a position and a direction vector of each vertex forming a mesh (step S230). At this time, interpolation of the direction vector generates a direction vector of the interpolated pixel. That is, the direction vector of the vertex is interpolated and defined as a direction vector of the interpolated pixel.

The temperature of each pixel is calculated using the direction vector of the interpolated pixel (S240). An infrared signal is obtained by adding an infrared signal radiated by the calculated temperature and a signal reflected by an external heat source such as the sun (S250 ).

At this time, the equation for calculating the pixel temperature is as follows, assuming a one-dimensional steady-state thermal conduction.

 Where h is the convection coefficient

A: Surface area

: 대기온도

: Ambient temperature

T ₀ : surface temperature to be obtained

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σ: Stefan-Bolzman constant

T _surr : Atmospheric radiation Apparent temperature

k: thermal conductance

T ₁ : Temperature of adjacent section in one dimensional heat conduction

: 1차원 열전도에서 구간의 간격

: Interval of interval in one-dimensional heat conduction

: 열발생율

: Heat generation rate

: 흡수율

: Absorption rate

G _D : Direct solar radiation

G _d : diffuse solar radiation

θ: Angle of incidence of direct solar radiation

In the above equations, the first term is convection, the second term is radiation, the third term is one-dimensional heat conduction, the fourth term is internal heat generation, and the fifth term is solar radiation. Solar radiation is divided into direct radiation and diffuse radiation, and direct radiation depends on the incident angle to the surface.

In the conventional method, a vertex direction vector is used to calculate the incidence angle of direct solar radiation in the above equation. In one embodiment of the present invention, the direction vector of the interpolated pixel is used. That is, cos is internally determined as a vector representing the direction vector of the pixel and the direction of the sun.

An example of the incident radiation in the heat transfer equation by interpolation of the direction vector is shown in FIG. 4 will be described later.

Continuing with reference to FIG. 2, an infrared signal is calculated from the calculated surface temperature.

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Referring to FIG. 2, the infrared ray signal is mapped to the color of the pixel, and the infrared ray image is output to the computer screen (S260).

3 is a configuration diagram of an infrared signal calculation apparatus 300 for generating an infrared image according to an embodiment of the present invention. 3, the infrared signal calculation apparatus 300 includes an input unit 310, a signal processing unit 320, an output unit 330, and the like.

The input unit 310 receives a CAD model of a three-dimensional shape as input, sets material and surface characteristics, and divides the triangle or square into a mesh-like shape to generate a vertex and a direction vector.

The signal processing unit 320 includes a projection unit 321 for interpolating a direction vector of a vertex to define a direction vector of a pixel, a shadow calculation unit 322 for setting a shadow image, a surface temperature calculation unit An infrared signal calculation unit 324 for performing infrared signal calculation using the direction vector of the pixel, and a mapping unit 325 for mapping the calculated infrared signal value to the color of the pixel . To this end, the signal processing unit 320 is constituted by hardware and / or a combination of software such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a memory.

The output unit 330 adjusts the size of the mapped infrared image and the position on the screen, and outputs the adjusted infrared image. Of course, the output unit 330 may include a display device or the like.

4 is a conceptual diagram for calculating incident energy by interpolation of a direction vector according to an embodiment of the present invention. Referring to FIG. 4, the incident energy is expressed as a product of an incident amount per unit area, a size of a surface, and an inner product of an incident direction and a direction vector of a surface.

Here, the sizes of the faces 1 and 2: width = 1, length =

Tilt to projection plane:

, 세로 =

Size of Projection Surface: Width =

, Height =

Solar incident amount per unit area: S

)은 투영면의 방향벡터를 이용하여 계산한 입사 에너지(Q)와 같음을 알 수 있다.In the above equation, the sum of the energy incident on each surface (

) Is equal to the incident energy (Q) calculated by using the direction vector of the projection plane.

As such, the direction vector is used in the calculation of the surface temperature 240 considering the solar incident energy, the calculation of the infrared signal emitted from the surface of the object, and the calculation of the reflection signal of the object surface inputted to the infrared sensor 250.

300: Infrared signal calculation device
310:
320:
321: Projection unit (3D? 2D)
322: Shadow calculation unit
323: surface temperature calculation unit
324: Infrared ray signal calculation unit
325: gray / color mapping unit
330: Output section

Claims (9)

A mesh dividing step of setting the material and surface characteristics of each part by inputting the three-dimensional CAD model of the shape and dividing the data into a mesh shape;
A two-dimensional infrared image generating step of generating a two-dimensional infrared image by interpolating a position and a direction vector of each vertex in a mesh shape to define a direction vector of the pixel;
Calculating an infrared signal value by calculating a surface temperature using a direction vector of a defined pixel and calculating an infrared signal value using the calculated temperature; And
A mapping step of mapping the calculated infrared signal value to a color of a pixel to generate an infrared image;
Dimensional temperature and infrared signal computation by direction vector interpolation.
The method according to claim 1,
Wherein a surface temperature is calculated with respect to pixels by calculating an incidence angle of a direct solar radiation using a direction vector of a pixel obtained by interpolating a direction vector of a vertex in the process of calculating the surface temperature, Temperature of shape and calculation method of infrared signal. The method according to claim 1,
The calculation of the temperature can be performed using Equation

(Where h: convection coefficient, A: surface area,

: T _{0 is} the surface temperature to be obtained, σ is the Stefan-Bolzman constant, T _{surr is the} atmospheric radiation apparent temperature, k is the thermal conductance, T _{1 is the} one dimensional heat conduction, The temperature of the adjacent section,

: Interval of interval in one dimensional heat conduction,

: Heat generation rate,

: Absorption rate, G _D : direct solar radiation, G _d : diffuse solar radiation, and θ: incidence angle of direct sun radiation). .
The method according to claim 1,
Wherein an infra-red signal is calculated with respect to a pixel by calculating an incident angle of solar radiation using a direction vector of a pixel obtained by interpolating a direction vector of a vertex in the infrared signal calculation process, Temperature and infrared signal calculation method.
delete 5. The method according to any one of claims 2 to 4,
Wherein the solar radiation is divided into direct radiation and diffuse radiation, wherein the direct sun radiation differs according to the angle incident on the pixel.
The method according to claim 1,
Wherein the color of the pixel is a gray or a color hue.
The method of claim 3,
Wherein the one-dimensional thermal conduction is a one-dimensional steady-state thermal conduction.
An input unit that receives a CAD model of a three-dimensional shape as input and sets material and surface characteristics, and divides the data into a mesh;
The direction vector of the pixel is defined by interpolating the position and the direction vector of each vertex in the form of a mesh, and the image is projected into a two-dimensional image. The temperature is calculated with respect to the direction vector of the defined pixel A signal processing unit for calculating an infrared signal value using the calculated temperature and mapping the calculated infrared signal value to the color of the pixel; And
An output unit for changing the size and position of the mapped infrared image;
Dimensional temperature and infrared ray signal calculating device by direction vector interpolation.

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