CN106441589A - Discretization-based planet infrared radiation simulation method - Google Patents

Abstract

The invention provides a discretization-based planet infrared radiation simulation method. The method includes the following steps that: (1) a planet rectangular coordinate system parallel to a geocentric rectangular coordinate system is built with the center of a planet adopted as an origin point; (2) the surface of the planet is discretized, discrete surface elements of the surface of the planet are traversed, whether the discrete surface elements are located within a field of view; (3) whether the discrete surface elements are located in a sun exposure area is judged, and the temperature of the surface elements is calculated according to included angles between the normal directions of the surface elements and a subsolar direction, and the subsolar point temperature and shadow temperature of the surface of the planet; and (4) the infrared radiation of the planet is calculated according to a black-body radiation models and a small surface element radiation model. With the method of the invention adopted, the transition of the surface temperature of the planet from a subsolar point to a shadow area is realized under a premise that the location information of the planet is known, and then, the infrared radiation of the planet can be calculated through the black-body radiation model. As indicated by simulation, the discretization-based planet infrared radiation simulation method of the invention can effectively carry out the simulation of the infrared radiation of the planet in the field of view of a sensor.

Description

A kind of planet infra-red radiation emulation mode based on sliding-model control

Technical field

The invention belongs to the technical field of Space Object Detection and identification, it is related to a kind of planet based on sliding-model control red External radiation emulation mode.

Background technology

The infrared characteristic of space background relate to space fixed star, planet and zodiacal infra-red radiation, space background red External radiation calculates the important evidence being Space Object Detection and identification, and zodiac impact therein is weaker, and fixed star is remote due to distance, And there is more constant radiation spectrum, but the radiation characteristic for planet, also there is no very effective Simulation Calculation.Root Can be in the hope of the initial position of solar system inner planet according to VSOP87C theory, that is, planet is under geocentric coordinate system, heliocentric coordinates Positional information, therefore can calculate planetary surface temperature by the geometrical relationship of the sun and planet, and then calculate the infrared of planet Radiation.While around solar motion,, also carrying out rotation, different moment, the sun can irradiate solar planet for itself To the diverse location of planet, meanwhile, when observing on earth, the different moment can observe the different part of planet, due to observation Region and to shine upon region be all time-varying, leads to face larger difficulty during the infra-red radiation observing planet on earth. The present invention passes through to turn to multiple bins by discrete for planetary surface, because bin area is less, is considered as temperature and uniformly radiates Source, can estimate the temperature of bin by judging the angle of bin normal and sun direct projection direction, by the spoke to whole bins Penetrate the infra-red radiation that summation can calculate planet.The infra-red radiation of planets of the solar system calculates result and will be applied to Space Object Detection And identification.

Content of the invention

Planetary temperature in field range is one of important parameter of planetary radiation amount emulation.Because planetary surface has day According to region and shadow region, and the temperature from subsolar point to shadow region is according to certain rule transition, tradition Temperature computation method do not consider this point, the unification of the temperature in sunshine region is thought the temperature of point of vertical, thus affecting The degree of accuracy of planetary surface temperature computation.The present invention carries out sliding-model control for planetary surface, sets up straight parallel to the earth's core Angular coordinate system, the rectangular coordinate system with the planet centre of sphere as initial point, the discretization bin on planet is traveled through successively, whether judges it It is in the range of sensor field of view, for the bin being in sunshine region, calculate its normal direction and the folder in sun direct projection direction Angle, such that it is able to calculate the temperature of this bin, for the point of shadow region, different point, because its temperature change is faint, adopt Shade temperature is uniformly processed, and can improve the accuracy in computation of temperature.Due to sliding-model control has been carried out to planetary surface, therefore Each discrete unit all can be regarded as small patches, is the uniform radiation source of temperature, according to black body radiation model and little face source spoke Penetrate model, by the infra-red radiation of planet can be calculated to the radiation summation of whole bins.

The present invention solve its technical problem employing technical scheme be：A kind of planet infra-red radiation based on sliding-model control Emulation mode, including step in detail below：

Step (1), the planet rectangular coordinate system parallel to geocentric rectangular coordinate system with the planet centre of sphere as initial point for the foundation

In each planet of the known solar system under the premise of the positional information under geocentric rectangular coordinate system, day heart rectangular coordinate system, When calculating field range inner planet surface temperature, according to geocentric rectangular coordinate system, the point of planetary surface is difficult to sitting Mark directly shows, and it is same to adopt day heart rectangular coordinate system there is a problem of, is therefore accomplished by setting up new coordinate system, is It is convenient to calculate and represent, the present invention establishes the planet right angle parallel to geocentric rectangular coordinate system, with the planet centre of sphere as initial point Coordinate system.In actual applications, calculate for convenience, first the horizontal system of coordinates is transformed into by edge according to sensor field of view sensing and regards Under the coordinate system of line direction, obtain the planetary position information under direction of visual lines coordinate system, judge whether this planet can be detected, If this planet is located in field range, carry out step (2), otherwise, change sensor boresight and point to continuation traversal.

Step (2), by planetary surface discretization, and to discrete bin travel through, judge whether it is in view field observation scope Interior

Due to planet rectangular coordinate system, geocentric rectangular coordinate system, sun rectangular coordinate system is parallel two-by-two, therefore planet The earth under coordinate system and position of sun information just can be obtained by simple Coordinate Conversion.Point on planetary surface is carried out Sliding-model control, travels through successively, tries to achieve each discrete bin to the distance of the earth, and and the line of the earth and the folder of boresight direction Angle, according to sensor field of view size and earth sight line and planet points of tangency to the distance of the earth, to judge that each discrete bin is No it is in visual field.Assume P for planetary surface a bit, sliding-model control for convenience, represented with the form of spherical coordinate systemWherein r is planet radius, and θ is the angle on planet between any point and Z axis,Arrive for any point on planet The projection of XOY plane and the angle of the line of the centre of sphere and X-axis.By θ,After sliding-model control, the shape that then spherical coordinates represented Formula is transformed into the discrete bin P (x, y, z) under the rectangular coordinate system with planet as initial point.

According to the parallel characteristic of coordinate system, coordinate P'(x' under geocentric coordinate system for the discrete bin of planetary surface, y', z') Add the side-play amount of the P opposing rows celestial body heart for coordinate under geocentric coordinate system for the planet centre of sphere.According to sensor boresight point to (A, H) by P'(x', y', z') project to along P under the coordinate system of direction of visual lines_r(x_r,y_r,z_r), A is the azimuth of sensor, and H is to bow The elevation angle.

Then calculate P_r(x_r,y_r,z_r) to the angle α between the line of the earth and the optical axis：

Next need to judge whether current bin P is in earth observation field range in addition it is also necessary to it is arrived with earth sight The distance that location is put is judged, because the earth can only observe the side towards the earth, when sight line and planet are tangent, tries to achieve The point that can observe apart from the maximum distance of the earth is：

Wherein,For the distance of the earth to the planet centre of sphere, r is planet radius.

So only whenP is just located in field range, and FOV is sensor field of view model Enclose.

Step (3), judge in visual field that whether discrete bin is located at sunshine region, and carry out bin temperature computation

After the completion of to the discrete bin position judgment on planet, need to continue to judge whether it is located at sunshine region, with Sample ground, calculates the distance between each discrete bin and the sun, according to sunray and planet points of tangency to the distance of the sun, judges Whether each discrete bin is in sunshine region, then calculates the angle in each discrete bin normal direction and sun direct projection direction, asks Obtain the temperature of each discrete bin.

Planetary position under known heliocentric coordinates, according to the parallel characteristic of coordinate system, to the planet under heliocentric coordinates Coordinate reindexing, you can obtain the sun coordinate under the coordinate being the former heart with the planet centre of sphere, S is position of sun.

Try to achieve the ultimate range that the sun and planet can reach towards sun side point：

For the distance of the sun to the planet centre of sphere, S is the position of the sun, and r is planet radius.

So only when the distance of planetary surface bin P and the sunMeetWhen, P is just located at sunshine region.

For the bin P in sunshine region, can be in the hope of planetary surface bin P normal direction and the sun according to the cosine law The angle in direct projection direction is β：

Then temperature t of each discrete bin of planetary surface_pCan calculate according to the following formula：

Wherein, t_sunsubTemperature for sun direct projection planet point；t_shadowFor planet shade temperature.

Step (4), calculating planet infra-red radiation

After obtaining certain discrete small patches temperature of planet, because bin area is less, it is considered as the uniform spoke of temperature Penetrate source, available Planck function solves the spectral radiant exitance of setted wavelength lower planet, then obtains radiance, according to Little face source radiation illuminance model, tries to achieve the planet bin radiant illumination in visual field, the radiation of each discrete bin is sued for peace Amount of infrared radiation to setted wavelength lower planet.

Finally, if the start-stop wavelength value of given sensor, can be by obtaining in this wave band to the summation of whole wave band upper integral The amount of infrared radiation of planet.

Present invention advantage compared with prior art is：

(1) rectangular coordinate system that the present invention is set up is with the planet centre of sphere for the former heart and parallel with geocentric coordinate system, Under the premise of knowing and doing star positional information it is only necessary to by simple vector operation just can complete planetary surface bin expression and time Go through；

(2) discretization method of the present invention travels through to planetary surface, the temperature of each discrete bin in sunshine region Degree is tried to achieve according to its normal direction and sun direct projection angular separation, gradually transition from point of vertical to shadow region, rather than adopts Single point of vertical temperature；

(3) present invention turns to multiple bins by discrete for planetary surface, because bin area is less, is considered as temperature uniform Radiation source, by the emulation of planet infra-red radiation can be completed to the radiation summation of whole bins.

Brief description

Fig. 1 is the flow chart that the present invention calculates planetary surface temperature based on sliding-model control；

Fig. 2 for the present invention set up parallel to geocentric coordinate system with planet rectangular coordinate system；

Fig. 3 judges for the present invention whether the bin on planet is in the schematic diagram in field range；

The little face source radiation model that Fig. 4 adopts for the present invention.

Specific embodiment

Below in conjunction with the accompanying drawings and specific embodiment further illustrates the present invention.

In the inner planet infra-red radiation simulation process of visual field, the present invention adopts the sliding-model control of planetary surface, sets up flat Row, in the planet centre of sphere rectangular coordinate system of geocentric coordinate system, travels through the bin of planetary surface successively, judges whether it is in visual field In the range of, for the bin in field range, can be estimated by judging bin normal direction and the angle in sun direct projection direction The temperature of bin, by calculating the infra-red radiation of planet to the radiation summation of whole bins.Its flow chart as shown in figure 1, Specifically include 4 steps.

1st, set up the planet rectangular coordinate system parallel to geocentric rectangular coordinate system with the planet centre of sphere as initial point

Can be in the hope of each planet of the solar system under geocentric rectangular coordinate system, day heart rectangular coordinate system according to VSOP87C theory Positional information.When calculating field range inner planet surface temperature, according to geocentric rectangular coordinate system, planetary surface Point is difficult to directly be showed with coordinate, and it is same to adopt day heart rectangular coordinate system there is a problem of, is therefore accomplished by setting up New coordinate system, in order to calculate and represent convenient, the present invention establishes parallel to geocentric rectangular coordinate system, is former with the planet centre of sphere The planet rectangular coordinate system of point.In actual applications, calculate for convenience, pointed to horizontal coordinate according to sensor field of view first System is transformed into along under direction of visual lines coordinate system, obtains the planetary position information under direction of visual lines coordinate system, whether judges this planet Can be detected, if this planet is located in field range, carry out step 2, otherwise, the optical axis changing sensor points to continuation time Go through.

2nd, by planetary surface discretization, and discrete bin is traveled through, judge whether it is in the range of view field observation

After setting up planet rectangular coordinate system, due to planet rectangular coordinate system, geocentric rectangular coordinate system, sun rectangular coordinate system It is parallel two-by-two, therefore the earth under planet coordinate system and position of sun information just can be obtained by simple Coordinate Conversion Arrive.Shown in Fig. 2, P be planetary surface a bit, sliding-model control for convenience, represent this point with the form of spherical coordinate system：Wherein r is planet radius, and θ is the angle on planet between any point and Z axis,Arrive for any point on planet The projection of XOY plane and the angle of the line of the centre of sphere and X-axis.By θ,After sliding-model control, the shape that then spherical coordinates represented Formula is converted to the Cartesian form under planet coordinate system：

Obtain the discrete bin P (x, y, z) under the rectangular coordinate system that planet is initial point.Δ θ=1rad, θ ∈ in the present invention [0,π],

According to the parallel characteristic of coordinate system, coordinate under geocentric coordinate system for the discrete bin P (x, y, z) on planetary surface P'(x',y',z')：

Wherein, O (x_o,y_o,z_o) it is position under geocentric coordinate system for the planet.

(A, H) is pointed to by P'(x', y', z' according to sensor boresight) project to along P under the coordinate system of direction of visual lines_r(x_r, y_r,z_r) (shown in Fig. 3), A is the azimuth of sensor, and H is the angle of pitch.

Then calculate P_r(x_r,y_r,z_r) to the angle α (shown in Fig. 3) between the line of the earth and the optical axis：

Next need to judge whether P is in earth observation field range in addition it is also necessary to arrive earth observation position to it Distance is judged, because the earth can only observe the side towards the earth, when sight line and planet are tangent, as shown in figure 3, asking Obtaining the point that can observe apart from the distance of the earth is：

Wherein,For the distance of the earth to the planet centre of sphere, r is planet radius.

So only whenP is just located in field range, and FOV is sensor field of view model Enclose.

3rd, judge that in visual field, whether discrete bin is located at sunshine region, and carry out bin temperature computation

After the completion of to the discrete bin position judgment on planet, need to continue to judge whether it is located at sunshine region, with Sample ground, calculates the distance between each discrete bin and the sun, according to sunray and planet points of tangency to the distance of the sun, judges Whether each discrete bin is in sunshine region, then calculates the angle β in each discrete bin normal direction and sun direct projection direction, asks Obtain the temperature of each discrete bin.

Planetary position under known heliocentric coordinates, according to the parallel characteristic of coordinate system, to the planet under heliocentric coordinates Coordinate reindexing, you can obtain the sun coordinate under the coordinate being the former heart with the planet centre of sphere, in Fig. 2, S is position of sun.

Try to achieve the ultimate range (shown in Fig. 2) that the sun and planet can reach towards sun side point：

For the distance of the sun to the planet centre of sphere, r is planet radius.

So only when the distance of planetary surface bin P and the sunMeetWhen, P is just located at sunshine region.

For the bin P in sunshine region, can be in the hope of planetary surface bin P normal direction and the sun according to the cosine law The angle in direct projection direction is β (shown in Fig. 2)：

Then temperature t of each discrete bin of planetary surface_pCan calculate according to the following formula：

Wherein, t_sunsubTemperature for sun direct projection planet point；t_shadowFor planet shade temperature.

4th, calculate planet infra-red radiation

After obtaining certain discrete small patches temperature of planet, because bin area is less, it is considered as the uniform spoke of temperature Penetrate source, available Planck function solves spectral radiant exitance M of setted wavelength λ lower planet bin_bb.

Planck function is given and is shown below：

In formula：H is Planck's constant, h=6.624 × 10^-34J·s；C is the light velocity；λ is given wavelength (μm)；K_BFor Boltzmann constant, K_B=1.38 × 10^-23J/K；T is the temperature of small patches；c₁For first radiation constant, c₁=(3.7415 ± 0.0003)×10⁸(W·μm⁴/m²)；c₂For second radiation constant, c₁=hc/k=(1.43879 ± 0.00019) × 10⁴(μm· K).

Obtain radiant exitance M of radiant body_bbAfterwards, radiance L is obtained according to following formula：

Then according to little face source radiation illuminance model (shown in Fig. 4), try to achieve the planet bin radiant illumination in visual field.

Little face source in radiant illumination produced by face to be illuminated is：

In Fig. 4, Δ A amasss for face to be illuminated, Δ A_sFor little face source area, Δ A_sIt is respectively θ with the normal of Δ A and the angle of l_sWith θ.

From step 2, after horizontal coordinate are transformed into along under the coordinate system of direction of visual lines, boresight direction is observation station The normal direction of E, so planetary surface bin P and the earth are wired to the angle theta=α of boresight direction.

And the normal direction of planetary surface bin P points to the planet centre of sphere, then θ_sIt is the folder between PO line and PE line Angle.

According to the cosine law, can be in the hope of θ_s：

Then little face source radiation illumination E, unit W/cm are obtained according to formula (10)², finally the radiation of each discrete bin is asked With the planet amount of infrared radiation obtaining under setted wavelength in visual field.

If start-stop wavelength value λ of given sensor_s、λ_e, can be by this wave band expert be obtained to the summation of whole wave band upper integral The amount of infrared radiation of star：

Δ (λ)=0.05 μm in the present invention.

In certain emulation, observation time is set to first day monthly of in January, 2014 to December, with dynamical time 0^hIt is defined, see Survey person's longitude and latitude is 100 ° of E, 20 ° of N, 1.5 degree of the angle of visual field, sensor start-stop wavelength X_s=8.0 μm, λ_e=10.0 μm, Mercury surface Subsolar point temperature be 620K, shade temperature be 103K.Firstly the need of traversal whole day ball, find the suitable optical axis and point to, Make Mercury in field range, then adopt the emulation mode of the present invention, calculate the amount of infrared radiation of Mercury, result of calculation such as table Shown in 1, demonstrate the validity of this method planet infra-red radiation emulation.

Table 1：Mercury infra-red radiation simulation result

The content not being described in detail in description of the invention belongs to prior art known to professional and technical personnel in the field.

Although disclosing embodiments of the invention and accompanying drawing for the purpose of illustration, those skilled in the art can manage Solution：Without departing from the spirit and scope of the invention and the appended claims, various replacements, to change and modifications be all possible 's.Therefore, the present invention should not be limited to the embodiment of the present invention and accompanying drawing disclosure of that.

Claims (4)

1. a kind of planet infra-red radiation emulation mode based on sliding-model control it is characterised in that：The method realize step such as Under：

Step (1), the planet rectangular coordinate system parallel to geocentric rectangular coordinate system with the planet centre of sphere as initial point for the foundation

In each planet of the known solar system under the premise of the positional information under geocentric rectangular coordinate system, day heart rectangular coordinate system, in order to It is convenient to calculate and represent, establishes parallel to geocentric rectangular coordinate system, and the planet rectangular coordinate system with the planet centre of sphere as initial point is first First pointed to according to sensor boresight and the horizontal system of coordinates is transformed into along under direction of visual lines coordinate system, obtain under direction of visual lines coordinate system Planetary position information, judge whether this planet can be detected, if this planet be located at field range in, carry out step (2), otherwise, change the optical axis and point to continuation traversal；

Step (2), by planetary surface discretization, and to discrete bin travel through, judge whether it is in the range of view field observation

Due to planet rectangular coordinate system, geocentric rectangular coordinate system, sun rectangular coordinate system is parallel two-by-two, therefore planet coordinate The earth under system and position of sun information just can be obtained by simple Coordinate Conversion, and planetary surface is carried out at discretization Reason, travels through each discrete bin successively, tries to achieve each discrete bin to the distance of the earth, and the line with the earth and boresight direction Angle, according to sensor field of view size and earth sight line and planet points of tangency to the distance of the earth, to judge each discrete bin Whether being in visual field, if being in visual field, carrying out step (3), otherwise, continue to travel through each discrete bin；

Step (3), judge in visual field that whether discrete bin is located at sunshine region, and carry out bin temperature computation

After the completion of to the discrete bin position judgment on planet, need to continue to judge whether each discrete bin is located at sunshine area Domain, similarly, calculates the distance between each discrete bin and the sun, according to sunray and planet points of tangency to the sun away from From judging whether each discrete bin is in sunshine region, by judging that the angle in bin normal direction and sun direct projection direction can To estimate the temperature of bin；

Step (4), calculating planet infra-red radiation

After obtaining certain discrete small patches temperature of planet, because bin area is less, it is considered as the uniform radiation source of temperature, By the infra-red radiation of planet can be calculated to the radiation summation of whole bins, setted wavelength can be solved according to Planck function The spectral radiant exitance of lower planet, then obtains radiance, according to little face source radiation illuminance model, tries to achieve the row in visual field Star bin radiant illumination, the radiation summation of each discrete bin be can get the amount of infrared radiation of setted wavelength lower planet；

Finally, if the start-stop wavelength value of given sensor, can be by this wave band inner planet be obtained to the summation of whole wave band upper integral Amount of infrared radiation.

2. a kind of planet infra-red radiation emulation mode based on sliding-model control according to claim 1, its feature exists In：The angle according to each discrete bin of planetary surface and earth line and boresight direction in described step (2), and the earth regards The distance of line and planet points of tangency to the earth to judge whether each discrete bin is in the method in field range：

Vacation lets p represent planetary surface a bit, represents this point with the form of spherical coordinate system：Wherein r is planet radius, θ For the angle between any point and Z axis on planet,Projection for any point on planet to XOY plane and the line of the centre of sphere With the angle of X-axis, by θ,After sliding-model control, the P then representing spherical coordinates form is transformed under planet rectangular coordinate system Discrete bin P (x, y, z)；

According to the parallel characteristic of coordinate system, coordinate P'(x' under geocentric coordinate system for the discrete bin on planetary surface, y', z') For coordinate under geocentric coordinate system for the planet centre of sphere add the P opposing rows celestial body heart side-play amount, according to sensor boresight point to (A, H) by P'(x', y', z') project to along P under the coordinate system of direction of visual lines_r(x_r,y_r,z_r), A is the azimuth of sensor, and H is to bow The elevation angle；

Then calculate P_r(x_r,y_r,z_r) to the angle α between the line of the earth and the optical axis：

$\mathrm{\α}=acos\left(\frac{\left|z_r\right|}{\sqrt{{x_r}^2+{y_r}^2+{z_r}^2}}\right)---\left(1\right)$

Next need to judge whether current bin P is in earth observation field range in addition it is also necessary to arrive earth observation position to it The distance put is judged, because the earth can only observe the side towards the earth, when sight line and planet are tangent, tries to achieve permissible The point observing apart from the maximum distance of the earth is：

$d_{max}=\sqrt{|\stackrel{\→}{EO}{|}^2-r^2}---\left(2\right)$

Wherein,For the distance of the earth to the planet centre of sphere, r is planet radius；

So only whenBin P is just located in visual field, and FOV is sensor field of view scope.

3. a kind of planet infra-red radiation emulation mode based on sliding-model control according to claim 2 it is characterised in that： According to sunray and planet points of tangency to the distance of the sun in described step (3), judge whether each discrete bin is in sunshine The method in region：

Try to achieve the ultimate range that the sun and planet can reach towards sun side point：

$l_{max}=\sqrt{|\stackrel{\→}{SO}{|}^2-r^2}---\left(3\right)$

For the distance of the sun to the planet centre of sphere, S is the position of the sun, and r is planet radius；

So only when the distance of planetary surface bin P and the sunMeetWhen, P is just located at sunshine region；

For the bin P in sunshine region, can be in the hope of planetary surface bin P normal direction and sun direct projection according to the cosine law The angle in direction is β：

$cos\left(\mathrm{\β}\right)=\frac{|\stackrel{\→}{SO}{|}^2+|\stackrel{\→}{OP}{|}^2-|\stackrel{\→}{SP}{|}^2}{2\·\left|\stackrel{\→}{SO}\right|\·\left|\stackrel{\→}{OP}\right|}---\left(4\right).$

4. a kind of planet infra-red radiation emulation mode based on sliding-model control according to claim 2, its feature exists In：The temperature computation method of the discrete bin of planet in described step (3)：

$\left\{\begin{array}{cc}{t}_p=t_{shadow}+\left(t_{sunsub}-t_{shadow}\right){\cos }^{\frac{1}{4}}\left(\mathrm{\β}\right),& \left|\stackrel{\→}{SP}\right|\≤l_{\max }\\ t_p=t_{shadow},& \left|\stackrel{\→}{SP}\right|>l_{\max }\end{array}\right.---\left(5\right)$

Wherein, t_sunsubTemperature for sun direct projection planet point；t_shadowFor planet shade temperature.