CN102346252A - Method and system for compensating atmospheric refraction in optical satellite remote sensing data geographic positioning - Google Patents

Abstract

The invention discloses a method and a system for compensating atmospheric refraction in optical satellite remote sensing data geographic positioning. The method for compensating the atmospheric refraction in the optical satellite remote sensing data geographic positioning comprises an earth radius compensating step, and is used for calculating the coordinate of a ground point corresponding to a certain pixel point in a satellite image by supposing that the earth radius is equal to the summation of the actual earth radius and the compensation amount of the earth radius. The method not only can be used for performing correction on the remote sensing data of SPOT-5, but also can be used for performing correction on other satellite remote sensing data; and due to the adoption of the method, the positioning accuracy after the compensation of the atmospheric refraction is obviously improved.

Description

Atmospheric refraction compensation method and system in the optical satellite remotely-sensed data geo-location

Technical field

The invention belongs to technical field of remote sensing image processing, relate to a kind of remote optical sensing satellite data geographic positioning, particularly a kind of method of in geo-location, passing through atmospheric refraction compensation raising bearing accuracy.

Background technology

Along with the continuous development of satellite earth observation technology on spatial resolution, spectral resolution, temporal resolution and observation mode; The comprehensive and quantitative of satellite remote sensing date is handled, increment is handled and profound application processes increasing demand is surging; Particularly in application processes such as the fusion of ground mapping, multi-source satellite remote sensing date, terrain object monitoring, the high precision geometry location problem of satellite remote sensing date has become the bottleneck problem that numerous remote sensing applications field needs to be resolved hurrily.Satellite remote sensing date high precision geometry location technology is one of key foundation support technology of satellite remote sensing date quantification processing, and its precision will directly influence the degree of depth that quantification is handled and increment is handled.

The geo-location of satellite remote-sensing image refers to the process of confirming the pairing ground location information of each pixel in the remote sensing images.For remote optical sensing, a certain instantaneous field of view of each pixel in the image during all with satellite earth observation is corresponding, and its ground location information comprises geographical longitude and latitude, floor level.The foundation of remote sensing image high-precision location is a photogrammetric Theory; One of gordian technique of its location is to set up the mathematical model of sensor imaging; Abbreviate imaging model as, what its reflected is exactly topocentric geographic coordinate and the mathematical relation of corresponding picture point between the cell coordinate of photo coordinate system.

In the remotely sensed image process,, thereby cause when the location, error can occurring because a variety of causes makes remote sensing image have distortion to a certain degree.Error, landform altitude sum of errors Atmospheric Refraction Error that the factor that causes the distortion of optical satellite image comprises systematic error that satellite ephemeris error, attitude of satellite error, instrument install, caused by earth curvature and earth rotation.

Surround Earth'S atmosphere and extend to several thousand kilometers height from ground always, can be divided into five layers from top to bottom: troposphere, stratosphere, middle layer, thermosphere and escape layer.When radiowave was propagated in atmospheric envelope, owing to the velocity of propagation in each layer changes the effect that produces atmospheric refraction, atmospheric envelope was uneven, and its refractive index changes along with the variation of height, causes the pixel point of remote sensing image to have displacement thus.For the hi-Fix of optical satellite remotely-sensed data, the error that atmospheric refraction causes can not ignore.

Summary of the invention

Technical matters to be solved by this invention is, atmospheric refraction compensation method and system in a kind of optical satellite remotely-sensed data geo-location are provided, and is significant to the geo-location precision that improves the optical satellite remotely-sensed data.

For achieving the above object; Atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location provided by the invention; Comprise an earth radius compensation process; Be used for through after earth radius is compensated, utilize the conventional imaging Model Calculation to obtain the corresponding topocentric coordinate of a certain pixel point in the satellite image again.

Atmospheric refraction compensation method in the above-mentioned optical satellite remotely-sensed data geo-location; It is characterized in that; Said earth radius being compensated in the step, is to add that through the hypothesis earth real radius earth radius compensation rate is that earth radius calculates the topocentric coordinate that obtains a certain pixel point correspondence in the satellite image.

Atmospheric refraction compensation method in the above-mentioned optical satellite remotely-sensed data geo-location is characterized in that obtaining further of said earth radius compensation rate comprises:

Pixel is used for obtaining a certain pixel point of optical satellite image with respect to substar direction deflection angle calculation procedure, utilizes the satellite metadata to calculate and obtains this pixel with respect to substar direction deflection angle;

Earth radius compensation rate and pixel be with respect to substar direction deflection angle corresponding relation establishment step, is used for setting up earth radius compensation rate and the pixel corresponding relation with respect to substar direction deflection angle according to optical principle and geometry probability;

Earth radius compensation rate calculation procedure, is calculated and is obtained the earth radius compensation rate with respect to substar direction deflection angle corresponding relation according to said earth radius compensation rate and pixel.

Atmospheric refraction compensation method in the above-mentioned optical satellite remotely-sensed data geo-location is characterized in that, said earth radius compensation rate and pixel are set up through following formula with respect to substar direction deflection angle corresponding relation:

$h=\frac{\sin \left(\mathrm{\θ}\right)\sin \left(\mathrm{\γ}\right)}{\sin \left(\mathrm{\β}\right)\sin (\mathrm{\β}+\mathrm{\γ})}(R+h^{\′})---\left(1\right)$

Wherein, $\mathrm{\β}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)---\left(2\right)$

$\mathrm{\γ}=\mathrm{\α}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{R+h^{\′}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(3\right)$

$\mathrm{\θ}=\mathrm{\β}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(4\right)$

With above-mentioned (2), (3), (4) formula substitution (1), promptly obtain said earth radius compensation rate and pixel with respect to substar direction deflection angle corresponding relation;

Wherein, λ is the deflection angle of this pixel with respect to the substar direction; α is the incident angle of light at place, the atmospheric envelope upper bound; α ' is the refraction angle of light in atmospheric envelope, and β is the incident angle at the corresponding ground point place of pixel, and γ and θ are the auxiliary angle that convenience of calculation is introduced; H is the satellite flight height; H ' is an atmospheric envelope thickness, and R is an earth radius, and h is the earth radius compensation rate.

The present invention further provides a kind of system that uses the atmospheric refraction compensation method in the above-mentioned optical satellite remotely-sensed data geo-location; It is characterized in that; Comprise an earth radius compensating module; Be used for through after earth radius is compensated, utilize the conventional imaging Model Calculation to obtain the corresponding topocentric coordinate of a certain pixel point in the satellite image again.

Said system; It is characterized in that; Said earth radius compensating module further comprises: pixel is used for obtaining a certain pixel point of optical satellite image with respect to substar direction deflection angle computing unit, utilizes the satellite metadata to calculate and obtains this pixel with respect to substar direction deflection angle; Earth radius compensation rate and pixel are set up the unit with respect to substar direction deflection angle corresponding relation, are used for setting up earth radius compensation rate and the pixel corresponding relation with respect to substar direction deflection angle according to optical principle and geometry probability; Earth radius compensation rate computing unit, calculates and obtains the earth radius compensation rate with respect to substar direction deflection angle corresponding relation according to said earth radius compensation rate and pixel.

Description of drawings

Fig. 1 is the principle schematic of atmospheric refraction compensation;

The curve that Fig. 2 changes with respect to substar direction deflection angle with pixel for the compensation radius;

Fig. 3 is the practical implementation schematic flow sheet of the atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location of the present invention;

Fig. 4 is the schematic block diagram of the atmospheric refraction bucking-out system in the optical satellite remotely-sensed data geo-location of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is done detailed description, further specifying book the object of the invention, scheme and effect, but appended graphic be not to be used to limit protection scope of the present invention.

The error that the objective of the invention is in optical satellite remotely-sensed data geo-location, atmospheric refraction to be caused compensates, thereby improves the geo-location precision.

For the compensation method of the present invention of clearer instructions; At first introduce the process of conventional optical satellite remotely-sensed data geo-location: the essence of carrying out the remote sensing image geo-location is exactly to set up a certain pixel coordinate (x of remote sensing image; Y) ground point (Lon corresponding with it; Lat) corresponding relation between, wherein Lon, Lat are respectively topocentric longitude and latitude.In order to carry out the geo-location of remote sensing image effectively, at first must set up the appropriate mathematic model of reflection imaging process, the model that promptly forms images, and this imaging model also is the theoretical foundation of geo-location, so be also referred to as the geo-location model.For the remote optical sensing satellite, in order to set up the analytical expression of corresponding relation between a certain pixel coordinate of the remote sensing image ground point corresponding with it, the geo-location model has utilized the rectilinear propagation principle of light.That is to say that the calculation process of asking of geo-location model is exactly to utilize the rectilinear propagation of light, calculate the visual field line of centres of satellite sensor and the process of earth surface point of crossing.

Yet, when the optical satellite actual imaging,, make to have deviation through the point of Model Calculation and the ground point of reality because there is certain refraction in atmospheric influence.Fig. 1 is the principle schematic of atmospheric refraction compensation; As shown in Figure 1, the ground point that pixel P is corresponding is A, and is A through the point of geo-location Model Calculation ₁, AA ₁Be because the positioning error that atmospheric refraction causes.

For the remote sensing satellite of middle low resolution, the positioning error that atmospheric refraction causes is very not serious, but for the high-definition remote sensing satellite, the positioning error that atmospheric refraction causes is not allowed to ignore.

, because improving bearing accuracy, the positioning error that atmospheric refraction causes is necessary atmospheric refraction is compensated in order to eliminate.But owing to receive environment, weather, Influence of Temperature, atmospheric refractive index changes whenever and wherever possible, is unpractical so it is set up analytic model.The present invention is from point of practical application, proposes a kind of feasible method that compensates for atmospheric refraction, and this method is introduced following basic assumption for this reason: the earth is the uniform spheroid of radius, and earth atmosphere also is uniform.

In Fig. 1, λ is the deflection angle of this pixel P with respect to the substar direction, and α is the incident angle of light at place, the atmospheric envelope upper bound, and α ' is the refraction angle of light in atmospheric envelope, and β is the incident angle at ground point A place, γ and the θ auxiliary angle for deriving and facilitating the introduction of.Suppose that the satellite flight height is H, atmospheric envelope thickness is h ', and earth radius is R.

As shown in Figure 1, connect the earth's core O with A and with its prolongation, with the rectilinear propagation path P A of light ₁Intersect at A ₂Point, A point and A ₂The pairing longitude and latitude of point is identical, as long as use A ₂The longitude and latitude that the longitude and latitude of point replaces A to order just can be eliminated because the error that atmospheric refraction produces.In order to obtain A ₂The longitude and latitude of point, this method are attempted earth radius is compensated, and the height of note compensation is h.

In Δ OPB, can obtain by the law of sines:

$\frac{\sin \left(\mathrm{\λ}\right)}{R+h^{\′}}=\frac{\sin \left(\mathrm{\α}\right)}{R+H}---\left(1\right)$

By (1) Shi Kede:

$\mathrm{\α}=\arcsin \left(\frac{R+H}{R+h^{\′}}\sin \left(\mathrm{\λ}\right)\right)---\left(2\right)$

If exoatmosphere sheaf space and atmospheric refractive index are respectively n ₁, n ₂, the refraction law according to light has so:

$\frac{\sin \left(\mathrm{\α}\right)}{\sin \left({\mathrm{\α}}^{\′}\right)}=\frac{n_2}{n_1}=n---\left(3\right)$

Can obtain by (1) formula and (3) formula:

$\sin \left({\mathrm{\α}}^{\′}\right)=\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)---\left(4\right)$

By (4) Shi Kede:

${\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(5\right)$

In Δ OAB, can obtain by the law of sines:

$\frac{\sin \left({\mathrm{\α}}^{\′}\right)}{R}=\frac{\sin \left(\mathrm{\β}\right)}{R+h^{\′}}---\left(6\right)$

Can obtain by (4) formula and (6) formula:

$\sin \left(\mathrm{\β}\right)=\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)---\left(7\right)$

Can obtain by (7) formula:

$\mathrm{\β}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)---\left(8\right)$

Equate and can obtain according to vertical angle:

$\mathrm{\γ}=\mathrm{\α}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{R+h^{\′}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(9\right)$

$\mathrm{\θ}=\mathrm{\β}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(10\right)$

At Δ ABA ₂In, can obtain by the law of sines:

$\frac{\sin \left(\mathrm{\γ}\right)}{h}=\frac{\sin (\mathrm{\β}+\mathrm{\γ})}{\mathrm{AB}}---\left(11\right)$

In Δ OAB, can obtain by the law of sines:

$\frac{\sin \left(\mathrm{\θ}\right)}{\mathrm{AB}}=\frac{\sin \left(\mathrm{\β}\right)}{R+h^{\′}}---\left(12\right)$

Can obtain by (11) formula and (12) formula:

$h=\frac{\sin \left(\mathrm{\θ}\right)\sin \left(\mathrm{\γ}\right)}{\sin \left(\mathrm{\β}\right)\sin (\mathrm{\β}+\mathrm{\γ})}(R+h^{\′})---\left(13\right)$

Bring (8) formula, (9) formula and (10) formula into (13) formula, can obtain h and this pixel P expression formula with respect to the deflection angle λ of substar direction.

Because (13) formula is an analytic formula,, be fit to practical engineering application so computing velocity is very fast.

(13) the formula earth radius h that shown compensation is along with pixel P changes with respect to the variation of substar direction deflection angle λ; Radius of a ball R=6370km hypothetically; The flying height H=780km of satellite; The earth atmosphere thickness h '=(the nethermost 85km of atmospheric envelope has occupied more than 99% of atmospheric envelope all-mass to 85km; So this is a reasonably hypothesis); Atmospheric refractive index n=1.0003, then the relation of h and λ as shown in Figure 2.

Can find out by diagramatic curve,, need the radius h of compensation big more, that is to say,, need the radius of compensation just big more along with the increase of pixel with respect to substar direction deflection angle along with the increase at λ angle.

What in sum, the present invention proposed compensates the method that improves bearing accuracy through atmospheric refraction in geo-location.With reference to figure 3, its practical implementation step is following:

Step S10: for a certain pixel point in the optical satellite image (x, y), wherein x for row number, y for the row number, utilize the satellite metadata to calculate this pixel with respect to substar direction deflection angle.

Step S20:, obtain the amount that earth radius compensates according to earth radius h and the pixel of compensation corresponding relation with respect to substar direction deflection angle λ.

Step S30: the radius of a ball is R+h hypothetically, utilize the conventional imaging Model Calculation obtain accordingly the coordinate of millet cake (Lon, Lat).

With the SPOT-5 data instance, the concrete grammar that in geo-location, carries out the atmospheric refraction compensation is described below:

Step 1: obtain a certain pixel point in the SPOT-5 image (x, y), x is row number, y is a row number; Obtain the imaging moment t=t of this pixel ₀+ line_period * (y-y ₀), t wherein ₀Be the photography moment of remote sensing image central row, y ₀Be the row number of central row, line_period is sweep time of each row; In the auxiliary data of remote sensing image, read corresponding almanac data, sensor attitude angle, attitude of satellite angle; Attitude angle according to sensor obtains that (x, y) pairing CCD visits the visual field vector of unit, thereby obtains this pixel with respect to substar direction deflection angle λ.

Step 2:, obtain the amount of earth compensation according to compensating earth radius h and pixel corresponding relation with respect to substar direction deflection angle λ.

Step 3: the radius of a ball is R+h hypothetically, utilize conventional imaging Model Calculation visual field vector and earth surface intersection point M (X, Y, Z); Utilize coordinate system conversion, with M (X, Y, Z) convert to geographic coordinate (Lon, Lat).

As shown in the table with the bearing accuracy contrast of not doing the atmosphere compensation through the bearing accuracy after the atmosphere compensation, the result shows, obviously improves through the bearing accuracy after the atmospheric refraction compensation.

	Mean longitude error (degree)	Mean latitude error (degree)
			Before the atmospheric refraction reparations	0.000172978	-1.17589e-05
After the atmospheric refraction reparations	-3.36052e-05	6.79581e-06

The method not only can be used for the remotely-sensed data of SPOT-5 is proofreaied and correct, and can also proofread and correct to other satellite remote sensing date.

The present invention further provides a kind of system 5 that uses the atmospheric refraction compensation method in the above-mentioned optical satellite remotely-sensed data geo-location; With reference to figure 4; This system 5 comprises an earth radius compensating module 50; Be used for through after earth radius is compensated, utilize the conventional imaging Model Calculation to obtain the corresponding topocentric coordinate of a certain pixel point in the satellite image again.This earth radius compensating module further comprises: pixel is used for obtaining a certain pixel point of optical satellite image with respect to substar direction deflection angle computing unit 501, utilizes the satellite metadata to calculate and obtains this pixel with respect to substar direction deflection angle; Earth radius compensation rate and pixel are set up unit 502 with respect to substar direction deflection angle corresponding relation, are used for setting up earth radius compensation rate and the pixel corresponding relation with respect to substar direction deflection angle according to optical principle and geometry probability; Earth radius compensation rate computing unit 503, calculates and obtains the earth radius compensation rate with respect to substar direction deflection angle corresponding relation according to said earth radius compensation rate and pixel.

Though the present invention discloses as above with preferred embodiment; Right its is not in order to limit the present invention; Under the situation that does not deviate from spirit of the present invention and essence thereof; Those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims (6)

1. the atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location; It is characterized in that; Comprise an earth radius compensation process, be used for, utilize the conventional imaging Model Calculation to obtain the corresponding topocentric coordinate of a certain pixel point in the satellite image again through after earth radius is compensated.

2. the atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location according to claim 1; It is characterized in that; Said earth radius being compensated in the step, is to add that through the hypothesis earth real radius earth radius compensation rate is that earth radius calculates the topocentric coordinate that obtains a certain pixel point correspondence in the satellite image.

3. the atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location according to claim 2 is characterized in that obtaining further of said earth radius compensation rate comprises:

Pixel is used for obtaining a certain pixel point of optical satellite image with respect to substar direction deflection angle calculation procedure, utilizes the satellite metadata to calculate and obtains this pixel with respect to substar direction deflection angle;

Earth radius compensation rate and pixel be with respect to substar direction deflection angle corresponding relation establishment step, is used for setting up earth radius compensation rate and the pixel corresponding relation with respect to substar direction deflection angle according to optical principle and geometry probability;

Earth radius compensation rate calculation procedure, is calculated and is obtained the earth radius compensation rate with respect to substar direction deflection angle corresponding relation according to said earth radius compensation rate and pixel.

4. the atmospheric refraction compensation method in the optical satellite remotely-sensed data geo-location according to claim 3 is characterized in that, said earth radius compensation rate and pixel are set up through following formula with respect to substar direction deflection angle corresponding relation:

$h=\frac{\sin \left(\mathrm{\θ}\right)\sin \left(\mathrm{\γ}\right)}{\sin \left(\mathrm{\β}\right)\sin (\mathrm{\β}+\mathrm{\γ})}(R+h^{\′})---\left(1\right)$

Wherein, $\mathrm{\β}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)---\left(2\right)$

$\mathrm{\γ}=\mathrm{\α}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{R+h^{\′}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(3\right)$

$\mathrm{\θ}=\mathrm{\β}-{\mathrm{\α}}^{\′}=\arcsin \left(\frac{R+H}{\mathrm{nR}}\sin \left(\mathrm{\λ}\right)\right)-\arcsin \left(\frac{R+H}{n(R+h^{\′})}\sin \left(\mathrm{\λ}\right)\right)---\left(4\right)$

With above-mentioned (2), (3), (4) formula substitution (1), promptly obtain said earth radius compensation rate and pixel with respect to substar direction deflection angle corresponding relation;

Wherein, λ is the deflection angle of this pixel with respect to the substar direction; α is the incident angle of light at place, the atmospheric envelope upper bound; α ' is the refraction angle of light in atmospheric envelope, and β is the incident angle at the corresponding ground point place of pixel, and γ and θ are the auxiliary angle that convenience of calculation is introduced; H is the satellite flight height; H ' is an atmospheric envelope thickness, and R is an earth radius, and h is the earth radius compensation rate.

5. an application rights requires the system of the atmospheric refraction compensation method in each described optical satellite remotely-sensed data geo-location in 1～4; It is characterized in that; Comprise an earth radius compensating module; Be used for through after earth radius is compensated, utilize the conventional imaging Model Calculation to obtain the corresponding topocentric coordinate of a certain pixel point in the satellite image again.

6. system according to claim 5 is characterized in that, said earth radius compensating module further comprises:

Pixel is used for obtaining a certain pixel point of optical satellite image with respect to substar direction deflection angle computing unit, utilizes the satellite metadata to calculate and obtains this pixel with respect to substar direction deflection angle;

Earth radius compensation rate and pixel are set up the unit with respect to substar direction deflection angle corresponding relation, are used for setting up earth radius compensation rate and the pixel corresponding relation with respect to substar direction deflection angle according to optical principle and geometry probability;

Earth radius compensation rate computing unit, calculates and obtains the earth radius compensation rate with respect to substar direction deflection angle corresponding relation according to said earth radius compensation rate and pixel.

Images