CN103067159B - A kind of reversible DecryptDecryption method of GIS vector data - Google Patents

Abstract

The invention discloses a kind of reversible DecryptDecryption method of GIS vector data, belong to field of geographic information safety.The method comprises following process: (1) key generation process, comprises and determines data area, determines data transformation amount, calculate medial error that linear transformation amount causes and determine parameter, calculate medial error that nonlinear transformation amount causes and determine parameter, to be encrypted key K ey with rivest, shamir, adelman RSA and stored in key file; (2) DecryptDecryption process, comprises reading key file, deciphers and extracts key; Open original vector data; Obtain the set of key element point coordinates; Unitary coordinate; Circular treatment; (3) recovery process.Method of the present invention has the features such as randomness, gradually changeable, invertibity, improves the reliability of GIS vector data DecryptDecryption, the perfect theory and means system of geography information safeguard protection, can be used for the aspect such as to publish of GIS vector data.

Description

A kind of reversible DecryptDecryption method of GIS vector data

Technical field

The invention belongs to field of geographic information safety, be specifically related to a kind of reversible DecryptDecryption method for GIS vector data.

Background technology

Survey and draw geography information concerning expansion development space, concerning national security.Especially, under the main trend of global IT application, geography information safety protection problem is more and more outstanding.Vector data has the features such as precision is high, output quality good, data volume is little, and application is very extensive, and its safeguard protection research is very important.

According to national relevant laws and regulations, vector data openly uses to be needed through DecryptDecryption process, and DecryptDecryption comprises spatial accuracy DecryptDecryption and attribute DecryptDecryption two aspects.Spatial accuracy DecryptDecryption uses professional DecryptDecryption technology to carry out the displacement of key element, reduce its precision, and the data after DecryptDecryption is not easily recovered when not having key.Spatial accuracy DecryptDecryption method conventional at present comprises projection transform method, spatial alternation method, random error interference method etc.Projection transform method is reversible; Data space converter technique comprises similarity transformation, affine transformation and projective transformation etc., and this several transform method is linear transformation, is easy to recover, the poor reliability of DecryptDecryption process; There is the topological relation that can not ensure key element or the shortcoming such as algorithm is irreversible in meeting that random error interference method has.

Summary of the invention

The present invention is directed to the defect that existing DecryptDecryption method exists, provide a kind of nonlinear mixed model to carry out the method for DecryptDecryption process to vector data, there is the randomness of error, the Topological of element relationship, the invertibity of algorithm and be difficult to features such as cracking.

A kind of reversible DecryptDecryption method of GIS vector data, for line chart layer, comprises following process:

(1) key generation process

Step 11, determines data area: the minimum enclosed rectangle R obtaining original vector data V, R lower left corner coordinate is (x _min, y _min), upper right corner coordinate is (x _max, y _max), obtain data center point coordinate (x according to formula (1) _mid, y _mid), data length XL and data width YL;

$\left\{\begin{array}{c}{x}_{\mathrm{mid}}=(x_{\min }+x_{\max })/2\\ y_{\mathrm{mid}}=(y_{\min }+y_{\max })/2\\ \mathrm{XL}=x_{\max }-x_{\min }\\ \mathrm{YL}=y_{\max }-y_{\min }\end{array}\right.---\left(1\right)$

Step 12, determine data transformation amount: concrete steps are as follows: input DATA POPULATION converted quantity offset, offset > 0, nonlinear transformation amount nonlinear, 0 < nonlinear <=offset, obtains linear transformation amount linear according to formula (2);

$\mathrm{linear}=\sqrt{{\mathrm{offset}}^2-{\mathrm{nonlinear}}^2}---\left(2\right)$

Step 13, calculates the medial error that linear transformation amount linear causes, determines the parameter affecting transform effect: focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, concrete steps are as follows:

C) focal distance f ∈ (0,1),

D) flying height H is calculated according to formula (3),

$H=\sqrt{\mathrm{XL}*\mathrm{YL}}/f---\left(3\right)$

C) the range of disturbance linearExtent of linear change amount linear is calculated according to formula (4),

$\mathrm{linearExtent}=\sqrt{\mathrm{linear}}---\left(4\right)$

D) generate control point set, concrete steps are as follows: within the scope of minimum enclosed rectangle R, generate m*n (m*n >=6) individual equal control point composition control point, source set FromPoints={ (Fx _i, Fy _i) | i=1,2 ... m*n}; Each target control point coordinates (Tx is calculated according to formula (5) _i, Ty _i) composition target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{Tx}}_i={\mathrm{Fx}}_i+{\mathrm{dir}}_1\&times;\mathrm{linear}+{\mathrm{random}}_1\&times;\mathrm{linearExtent}\\ {\mathrm{Ty}}_i={\mathrm{Fy}}_i+{\mathrm{dir}}_2\&times;\mathrm{linear}+{\mathrm{random}}_2\&times;\mathrm{linearExtent}\end{array}\right.---\left(5\right)$

Wherein: directioin parameter dir ₁in [0.0,1.0] scope, directioin parameter perturbation of control points parameter random ₁and random ₂random selecting in [-1.0,1.0] scope,

E) Unitary coordinate, is normalized according to formula (6) obtains new coordinate set FromPoints '={ (Fx to control point, source set FromPoints and target control point set ToPoints _i', Fy _i') | i=1,2 ... m*n}, ToPoints '={ (Tx _i', Ty _i') | i=1,2 ... m*n},

$\left\{\begin{array}{c}{{\mathrm{Fx}}_i}^{\&prime;}=({\mathrm{Fx}}_i-x_{\mathrm{mid}})*f/H\\ {{\mathrm{Fy}}_i}^{\&prime;}=({\mathrm{Fy}}_i-y_{\mathrm{mid}})*f/H\\ {{\mathrm{Tx}}_i}^{\&prime;}=({\mathrm{Tx}}_i-x_{\mathrm{mid}})*f/H\\ {{\mathrm{Ty}}_i}^{\&prime;}=({\mathrm{Ty}}_i-y_{\mathrm{mid}})*f/H\end{array}\right.---\left(6\right)$

F) drift angle is calculated inclination angle ω, swing angle κ, utilize least square method to carry out matching to target control point in FromPoints ' Zhong Yuan control point and ToPoints ' according to formula (7) and resolve and obtain drift angle inclination angle ω, swing angle κ,

G) linear transformation medial error accuracy is calculated ₁, concrete steps are as follows: obtain target control point set ToPoints according to formula (8) conversion source control point set FromPoints ' coordinate " and={ (Tx _i", Ty _i") | i=1,2 ... m*n},

Medial error accuracy1 is calculated according to formula (9),

${\mathrm{accuracy}}_1=\sqrt{\mathrm{\&Sigma;}({({{\mathrm{Tx}}_i}^{\&prime;\&prime;}-{\mathrm{Fx}}_i)}^2+{({{\mathrm{Ty}}_i}^{\&prime;\&prime;}-{\mathrm{Fy}}_i)}^2)/(m*n)}---\left(9\right)$

H) regulate the set of target control point, concrete steps are as follows: if | linear/accuracy ₁-1| > 0.01, then regulate each former target control point coordinates (Tx according to formula (10) _i, Ty _i), obtain new target control point coordinates (NTx _i, NTy _i), substitute former target control point and Tx with new target control point _i=NTx _i, Ty _i=NTy _i, obtain target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{NTx}}_i={\mathrm{Fx}}_i+(\mathrm{linear}/\mathrm{accuracy})({\mathrm{Tx}}_i-{\mathrm{Fx}}_i)\\ {\mathrm{NTy}}_i={\mathrm{Fy}}_i+(\mathrm{linear}/\mathrm{accuracy})({\mathrm{Ty}}_i-{\mathrm{Fy}}_i)\end{array}\right.---\left(10\right)$

I) circulation step e)-h) until | linear/accuracy ₁-1| <=0.01, obtains final drift angle inclination angle ω, swing angle κ;

Step 14, calculates the medial error that nonlinear transformation amount nonlinear causes, determines parameter j ₀-j ₅, concrete steps are as follows:

B) generate control point elevation, utilize the elevation Fz needed for formula (11) calculating control point, source set FromPoints each some displacement nonlinear _i, generate three-dimensional source control point set FromPoints={ (Fx _i, Fy _i, Fz _i) | i=1,2 ... m*n},

${\mathrm{Fz}}_i=H*\mathrm{nonlinear}/\sqrt{{(x_{\mathrm{mid}}-{\mathrm{Fx}}_i)}^2+{(y_{\mathrm{mid}}-{\mathrm{Fy}}_i)}^2}---\left(11\right)$

B) carry out least square according to formula (12) to the three-dimensional source control point set FromPoints generated to resolve, obtain parameter j ₀-j ₅,

Fz _i＝j ₀+j ₁Fx _i+j ₂Fy _i+j ₃Fx _i ²+j ₄Fy _i ²+j ₅Fx _iFy _i(12)

C) nonlinear transformation medial error accuracy is calculated ₂, concrete steps are as follows: according to formula (12) and parameter j ₀-j ₅resolve the Fz at control point, each source _ivalue, is saved in three-dimensional source control point set FromPoints, calculates target control point set ToPoints={ (Tx according to formula (13) to three-dimensional source control point set FromPoints _i, Ty _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{Tx}}_i=(-f({\mathrm{Fx}}_i-x_{\mathrm{mid}})/({\mathrm{Fz}}_i-H))*H/f+x_{\mathrm{mid}}\\ {\mathrm{Ty}}_i=(-f({\mathrm{Fy}}_i-y_{\mathrm{mid}})/({\mathrm{Fz}}_i-H))*H/f+y_{\mathrm{mid}}\end{array}\right.---\left(13\right)$

Medial error accuracy is calculated according to formula (14) ₂,

${\mathrm{accuracy}}_2=\sqrt{\mathrm{\&Sigma;}({({\mathrm{Tx}}_i-{\mathrm{Fx}}_i)}^2+{({\mathrm{Ty}}_i-{\mathrm{Fy}}_i)}^2)/(m*n)}---\left(14\right)$

D) control point, source height value is regulated, if | nonlinear/accuracy ₂-1| > 0.01, then regulate control point, each source coordinate height value according to formula (15), obtain new height value NFzi, substitute former height value and Fzi=NFzi by new height value, obtain three-dimensional source control point set FromPoints={ (Fx _i, Fy _i, Fz _i) | i=1,2 ... m*n},

$\left\{\begin{array}{cc}{\mathrm{NFz}}_i\&Element;({\mathrm{Fz}}_i/2,\left({\mathrm{nonlinear}/\mathrm{accuracy}}_2\right)*{\mathrm{Fz}}_i)& \mathrm{if}({\mathrm{nonlinear}/\mathrm{accuracy}}_2>1)\\ {\mathrm{NFz}}_i\&Element;(\left({\mathrm{nonlinear}/\mathrm{accuracy}}_2\right)*{\mathrm{Fz}}_i/2,{\mathrm{Fz}}_i)& \mathrm{if}({\mathrm{nonlinear}/\mathrm{accuracy}}_2<1)\end{array}\right.---\left(15\right)$

E) circulation step b)-d), until | nonlinear/accuracy ₂-1| <=0.01, obtains final argument j ₀-j ₅;

Step 15, focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, data center point coordinates (x _mid, y _mid), parameter j ₀-j ₅composition key K ey, to be encrypted key K ey with rivest, shamir, adelman RSA and stored in key file Key.txt;

(2) DecryptDecryption process

Step 21, reads key file Key.txt, extracts key K ey, open original vector data V after deciphering;

Step 22, generates each point height value z _j, converted coordinate, concrete steps are as follows:

A) extract the key element point coordinates of vector data V, obtain key element point coordinates set P={ (x _j, y _j, z _j) | j=1,2 ..., k}, wherein k is the some number that key element comprises,

B) according to each point coordinates p in key K ey and formula (16) cycle calculations set P _j(x _j, y _j, z _j) height value z _jand be saved in set P,

z _j＝j ₀+j ₁x _j+j ₂y _j+j ₃x _j ²+j ₄y _j ²+j ₅x _jy _j(16)

C) according to formula (17) and key K ey, to each point coordinates p _j(x _j, y _j, z _j) calculate, obtain point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k};

Step 23, Unitary coordinate, according to key K ey and formula (18) to each point coordinates p _j' (x _j', y _j', z _j) be normalized obtain point coordinates set P after DecryptDecryption "={ (x _j", y _j", z _j) | j=1,2 ..., k};

$\left\{\begin{array}{c}{x_j}^{\&prime;\&prime;}=x_{\mathrm{mid}}+{x_j}^{\&prime;}*H/f\\ {y_j}^{\&prime;\&prime;}=y_{\mathrm{mid}}+{y_j}^{\&prime;}*H/f\end{array}\right.---\left(18\right)$

Step 24, circulation step 22 to 23, until each key element is disposed, preserves the data file W after DecryptDecryption;

(3) recovery process

Step 31, reads key file Key.txt, extracts key K ey, open the vector data W after DecryptDecryption after deciphering;

Step 32, Unitary coordinate, concrete steps are as follows:

A) extract the key element point coordinates of vector data W, obtain coordinate set P "={ (x _j", y _j", z _j) | j=1,2 ..., k},

B) according to key K ey and formula (19), to set P " set in each point coordinates p _j" (x _j", y _j", z _j) be normalized generation point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k;

$\left\{\begin{array}{c}{x_j}^{\&prime;}=({x_j}^{\&prime;\&prime;}-x_{\mathrm{mid}})*f/H\\ {y_j}^{\&prime;}=({y_j}^{\&prime;\&prime;}-y_{\mathrm{mid}})*f/H\end{array}\right.---\left(19\right)$

Step 33, converted coordinate, according to formula (20) and key K ey to each point coordinates p _j' (x _j', y _j', z _j) calculate, then by height value z _jzero setting, the point coordinates p after being restored _j(x _j, y _j, 0), generate coordinate set P={ (x _j, y _j, 0) | j=1,2 ..., k};

Step 34, circulation step 32 to 33, until each key element is disposed, the data file Q after saving/restoring.

The present invention proposes a kind of nonlinear mixed model and DecryptDecryption and Recovery processing are carried out to GIS vector data.This method, for the safety protection problem of GIS vector data, is ensureing that, under the prerequisite that vector data topological relation does not change, can carry out DecryptDecryption to data according to key, the data after DecryptDecryption can carry out Distortionless according to key.This method has the features such as randomness, gradually changeable, invertibity, improves the reliability of GIS vector data DecryptDecryption, the perfect theory and means system of geography information safeguard protection, can be used for the aspect such as to publish of GIS vector data.

Accompanying drawing explanation

Fig. 1 is the inventive method DecryptDecryption process flow diagram.

Fig. 2 is the inventive method recovery process flow chart.

Fig. 3 is the original vector data that the embodiment of the present invention is selected.

Fig. 4 is the design sketch of vector data superposition after initial data of the present invention and DecryptDecryption.

Embodiment

Below in conjunction with accompanying drawing, embodiments of the invention are elaborated.

The present embodiment selects shp form vector data, reads, DecryptDecryption and recovery operation to data, further describes the present invention.The present embodiment selects the shp line chart layer data (as Fig. 3) of a certain building as original vector data, comprises the following steps:

(1) key generation process

Step 11, determine data area: the minimum enclosed rectangle R obtaining original vector data V, R lower left corner coordinate is (123451.63676768,142705.11870332), upper right corner coordinate is (123726.302067681,142994.494303319), data center point coordinate (123588.969417681,142849.80650332), data length XL=274.665300000459 and data width YL=289.375599998981 is obtained according to formula (1);

Step 12, determine data transformation amount: concrete steps are as follows: input DATA POPULATION converted quantity offset=50, nonlinear transformation amount nonlinear=7, obtains linear transformation amount linear=49.5075751779463 according to formula (2);

Step 13, calculates the medial error that linear transformation amount linear causes, determines the parameter affecting transform effect: focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, concrete steps are as follows:

E) focal distance f=0.15,

F) flying height H=1879.49681193348 is calculated according to formula (3),

C) the range of disturbance linearExtent=7.03616196359537 of linear change amount linear is calculated according to formula (4),

D) generate control point set, concrete steps are as follows: within the scope of minimum enclosed rectangle R, generate 4*4 equal control point composition control point, source set FromPoints={ (Fx _i, Fy _i) | i=1,2 ... 4*4}; Each target control point coordinates (Tx is calculated according to formula (5) _i, Ty _i) composition target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... 4*4},

E) Unitary coordinate, is normalized according to formula (6) obtains new coordinate set FromPoints '={ (Fx to control point, source set FromPoints and target control point set ToPoints _i', Fy _i') | i=1,2 ... 4*4}, ToPoints '={ (Tx _i', Ty _i') | i=1,2 ... 4*4},

F) drift angle is calculated inclination angle ω, swing angle κ, utilize least square method to carry out matching to target control point in FromPoints ' Zhong Yuan control point and ToPoints ' according to formula (7) and resolve and obtain drift angle ω=0.00921638185358357, inclination angle, swing angle κ=0.0206308078601073,

G) linear transformation medial error accuracy is calculated ₁, concrete steps are as follows: obtain target control point set ToPoints according to formula (8) conversion source control point set FromPoints ' coordinate " and={ (Tx _i", Ty _i") | i=1,2 ... 4*4}, calculates medial error accuracy according to formula (9) ₁=50.6202842886151,

H) regulate the set of target control point, concrete steps are as follows: if | linear/accuracy ₁-1| > 0.01, then regulate each former target control point coordinates (Tx according to formula (10) _i, Ty _i), obtain new target control point coordinates (NTx _i, NTy _i), substitute former target control point and Tx with new target control point _i=NTx _i, Ty _i=NTy _i, obtain target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... 4*4},

I) circulation step e)-h), work as accuracy ₁when=49.5075776592392 | linear/accuracy ₁-1| <=0.01, obtains final drift angle ω=0.00901382354283439, inclination angle, swing angle κ=0.0201770830635741;

Step 14, calculates the medial error that nonlinear transformation amount nonlinear causes, determines parameter j ₀-j ₅, concrete steps are as follows:

A) generate control point elevation, utilize the elevation Fz needed for formula (11) calculating control point, source set FromPoints each some displacement nonlinear _i, generate three-dimensional source control point set FromPoints={ (Fx _i, Fy _i, Fz _i) | i=1,2 ... 4*4},

B) carry out least square according to formula (12) to the three-dimensional source control point set FromPoints generated to resolve, obtain parameter j ₀=-134576645.0625, j ₁=957.075539588928, j ₂=1056.14212036133, j ₃=-0.00386110281764473, j ₄=-0.00368852281107479, j ₅=-1.88736757991137E-05,

C) nonlinear transformation medial error accuracy is calculated ₂, concrete steps are as follows: according to formula (12) and parameter j ₀-j ₅resolve the Fz at control point, each source _ivalue, is saved in three-dimensional source control point set FromPoints, calculates target control point set ToPoints={ (Tx according to formula (13) to three-dimensional source control point set FromPoints _i, Ty _i) | i=1,2 ... 4*4}, calculates medial error accuracy according to formula (14) ₂=8.33449148774509,

D) control point, source height value is regulated, if | nonlinear/accuracy ₂-1| > 0.01, then regulate control point, each source coordinate height value according to formula (15), obtain new height value NFzi, substitute former height value and Fzi=NFzi by new height value, obtain three-dimensional source control point set FromPoints={ (Fx _i, Fy _i, Fz _i) | i=1,2 ... 4*4},

E) circulation step b)-d), work as accuracy ₂when=6.9961779687363 | nonlinear/accuracy ₂-1| <=0.01, obtains final argument j ₀=-92384371.34375, j ₁=544.834728956223, j ₂=822.104847669601, j ₃=-0.00253963583136851, j ₄=-0.00312865154306508, j ₅=0.000580351679673186;

Step 15, focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, data center point coordinates (x _mid, y _mid), parameter j ₀-j ₅composition key K ey, to be encrypted key K ey with rivest, shamir, adelman RSA and stored in key file Key.txt;

(2) DecryptDecryption process

Step 21, reads key file Key.txt, extracts key K ey, open original vector data V after deciphering;

Step 22, generates each point height value z _j, converted coordinate, concrete steps are as follows:

A) extract the key element point coordinates of vector data V, obtain key element point coordinates set P={ (x _j, y _j, z _j) | j=1,2 ..., k}, wherein k is the some number that key element comprises, below with 1 p (123677.937667681,142928.252103319,0) in P for example is described,

B) according to each point coordinates p in key K ey and formula (16) cycle calculations set P _j(x _j, y _j, z _j) height value z _jand be saved in set P, the height value z=119.892017556354 of example points p,

C) according to formula (17) and key K ey, to each point coordinates p _j(x _j, y _j, z _j) calculate, obtain point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k}, example points p (123677.937667681,142928.252103319,119.892017556354) point coordinates after changing is p ' (0.00402027927973795,0.00517358718854751,119.892017556354);

Step 23, Unitary coordinate, according to key K ey and formula (18) to each point coordinates p _j' (x _j', y _j', z _j) be normalized obtain point coordinates set P after DecryptDecryption "={ (x _j", y _j", z _j) | j=1,2 ..., after k}, some p ' normalization, point coordinates is p " (123639.34343161,142914.631440834,119.892017556354);

Step 24, circulation step 22 to 23, until each key element is disposed, preserves the data file W after DecryptDecryption;

(3) recovery process

Step 31, reads key file Key.txt, extracts key K ey, open the vector data W after DecryptDecryption after deciphering;

Step 32, Unitary coordinate, concrete steps are as follows:

A) extract the key element point coordinates of vector data W, obtain coordinate set P "={ (x _j", y _j", z _j) | j=1,2 ..., k}, below with a P " in 1 p " (123639.34343161,142914.631440834,119.892017556354) be described for example,

B) according to key K ey and formula (19), to set P " set in each point coordinates p _j" (x _j", y _j", z _j) be normalized generation point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k}, to example points p " be normalized and obtain a p ' (0.00402027927973827,0.00517358718854753,119.892017556354);

Step 33, converted coordinate, according to formula (20) and key K ey to each point coordinates p _j' (x _j', y _j', z _j) calculate, then by height value z _jzero setting, the point coordinates p after being restored _j(x _j, y _j, 0), generate coordinate set P={ (x _j, y _j, 0) | j=1,2 ..., k}, change p ' coordinate be restored after point coordinates be p (123677.937667681,142928.252103319,0);

Step 34, circulation step 32 to 33, until each key element is disposed, the data file Q after saving/restoring.

Only carry out DecryptDecryption and the recovery of vector data in the embodiment of the present invention for line chart layer, the method also can be used for DecryptDecryption and the recovery of a layer and face layer.

The present invention is ensureing to carry out DecryptDecryption and recovery to vector data under the prerequisite that vector data topological relation does not change, and can setup parameter is to reach required DecryptDecryption effect according to demand, and the data after DecryptDecryption can carry out Distortionless according to key.

Claims (1)

1. the reversible DecryptDecryption method of GIS vector data, is characterized in that, comprise following process:

(1) key generation process

Step 11, determines data area: the minimum enclosed rectangle R obtaining original vector data V, R lower left corner coordinate is (x _min, y _min), upper right corner coordinate is (x _max, y _max), obtain data center point coordinate (x according to formula (1) _mid, y _mid), data length XL and data width YL;

$\left\{\begin{array}{c}{x}_{mid}=(x_{min}+x_{max})/2\\ y_{mid}=(y_{min}+y_{max})/2\\ XL=x_{\max }-x_{min}\\ YL=y_{\max }-y_{min}\end{array}\right.---\left(1\right)$

Step 12, determine data transformation amount: concrete steps are as follows: input DATA POPULATION converted quantity offset, offset>0, nonlinear transformation amount nonlinear, 0<nonlinear<=offset, obtains linear transformation amount linear according to formula (2);

$linear=\sqrt{{\mathrm{offset}}^2-{\mathrm{nonlinear}}^2}---\left(2\right)$

Step 13, calculates the medial error that linear transformation amount linear causes, determines the parameter affecting transform effect: focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, concrete steps are as follows:

131) focal distance f ∈ (0,1),

132) flying height H is calculated according to formula (3),

$H=\sqrt{XL*YL}/f---\left(3\right)$

133) the range of disturbance linearExtent of linear transformation amount linear is calculated according to formula (4),

$linearExtent=\sqrt{linear}---\left(4\right)$

134) generate control point set, concrete steps are as follows: within the scope of minimum enclosed rectangle R, generate m*n equal control point composition control point, source set FromPoints={ (Fx _i, Fy _i) | i=1,2 ... m*n}, m*n>=6; Each target control point coordinates (Tx is calculated according to formula (5) _i, Ty _i) composition target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{Tx}}_i={\mathrm{Fx}}_i+{\mathrm{dir}}_1\&times;linear+{\mathrm{random}}_1\&times;linearExtent\\ {\mathrm{Ty}}_i={\mathrm{Fy}}_i+{\mathrm{dir}}_2\&times;linear+{\mathrm{random}}_2\&times;linearExtent\end{array}\right.---\left(5\right)$

Wherein: directioin parameter dir ₁in [0.0,1.0] scope, directioin parameter perturbation of control points parameter random ₁and random ₂random selecting in [-1.0,1.0] scope,

135) Unitary coordinate, is normalized according to formula (6) obtains new coordinate set FromPoints '={ (Fx to control point, source set FromPoints and target control point set ToPoints _i', Fy _i') | i=1,2 ... m*n}, ToPoints '={ (Tx _i', Ty _i') | i=1,2 ... m*n},

$\left\{\begin{array}{c}{{\mathrm{Fx}}_i}^{\&prime;}=({\mathrm{Fx}}_i-x_{mid})*f/H\\ {{\mathrm{Fy}}_i}^{\&prime;}=({\mathrm{Fy}}_i-y_{mid})*f/H\\ {{\mathrm{Tx}}_i}^{\&prime;}=({\mathrm{Tx}}_i-x_{mid})*f/H\\ {{\mathrm{Ty}}_i}^{\&prime;}=({\mathrm{Ty}}_i-y_{mid})*f/H\end{array}\right.---\left(6\right)$

136) drift angle is calculated inclination angle ω, swing angle κ, utilize least square method to carry out matching to target control point in FromPoints ' Zhong Yuan control point and ToPoints ' according to formula (7) and resolve and obtain drift angle inclination angle ω, swing angle κ,

137) linear transformation medial error accuracy is calculated ₁, concrete steps are as follows: obtain target control point set ToPoints according to formula (8) conversion source control point set FromPoints ' coordinate " and={ (Tx _i", Ty _i") | i=1,2 ... m*n},

Medial error accuracy is calculated according to formula (9) ₁,

${\mathrm{accuracy}}_1=\sqrt{\mathrm{\&Sigma;}({\left({{\mathrm{Tx}}_i}^{\&prime;\&prime;}-{\mathrm{Fx}}_i\right)}^2+{\left({{\mathrm{Ty}}_i}^{\&prime;\&prime;}-{\mathrm{Fy}}_i\right)}^2)/(m*n)}---\left(9\right)$

138) regulate the set of target control point, concrete steps are as follows: if | linear/accuracy ₁-1|>0.01, then regulate each former target control point coordinates (Tx according to formula (10) _i, Ty _i), obtain new target control point coordinates (NTx _i, NTy _i), substitute former target control point and Tx with new target control point _i=NTx _i, Ty _i=NTy _i, obtain new target control point set NTToPoints={ (NTx _i, NTy _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{NTx}}_i={\mathrm{Fx}}_i+(linear/{\mathrm{accuracy}}_1)({\mathrm{Tx}}_i-{\mathrm{Fx}}_i)\\ {\mathrm{NTy}}_i={\mathrm{Fy}}_i+(linear/{\mathrm{accuracy}}_1)({\mathrm{Ty}}_i-{\mathrm{Fy}}_i)\end{array}\right.---\left(10\right)$

139) circulation step 135)-138) until | linear/accuracy ₁-1|<=0.01, obtains final drift angle inclination angle ω, swing angle κ;

Step 14, calculates the medial error that nonlinear transformation amount nonlinear causes, determines parameter j ₀, j ₁, j ₂, j ₃, j ₄and j ₅, concrete steps are as follows:

141) generate control point elevation, utilize the elevation Mz needed for formula (11) calculating control point, source set FromPoints each some displacement nonlinear _i, generate three-dimensional source control point set MFromPoints={ (Mx _i, My _i, Mz _i) | i=1,2 ... m*n},

${\mathrm{Mz}}_i=H*nonlinear/\sqrt{{(x_{mid}-{\mathrm{Mx}}_i)}^2+{(y_{mid}-{\mathrm{My}}_i)}^2}---\left(11\right)$

142) carry out least square according to formula (12) to the three-dimensional source control point set MFromPoints generated to resolve, obtain parameter j ₀, j ₁, j ₂, j ₃, j ₄and j ₅,

Mz _i’＝j ₀+j ₁Mx _i+j ₂My _i+j ₃Mx _i ²+j ₄My _i ²+j ₅Mx _iMy _i(12)

143) nonlinear transformation medial error accuracy is calculated ₂, concrete steps are as follows: according to formula (12) and parameter j ₀, j ₁, j ₂, j ₃, j ₄and j ₅resolve the Mz at control point, each source _i' value, be saved in three-dimensional source control point set MFromPoints, according to formula (13), target control point set NToPoints={ (Nx calculated to three-dimensional source control point set MFromPoints _i, Ny _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{Nx}}_i=(-f({\mathrm{Mx}}_i-x_{\mathrm{mi}d})/({{\mathrm{Mz}}_i}^{\&prime;}-H\left)\right)*H/f+x_{mid}\\ {\mathrm{Ny}}_i=(-f({\mathrm{My}}_i-y_{mid})/({{\mathrm{Mz}}_i}^{\&prime;}-H\left)\right)*H/f+y_{mid}\end{array}\right.---\left(13\right)$

Medial error accuracy is calculated according to formula (14) ₂,

${\mathrm{accuracy}}_2=\sqrt{\mathrm{\&Sigma;}({\left({\mathrm{Nx}}_i-{\mathrm{Mx}}_i\right)}^2+{\left({\mathrm{Ty}}_i-{\mathrm{My}}_i\right)}^2)/(m*n)}---\left(14\right)$

144) control point, source height value is regulated, if | nonlinear/accuracy ₂-1|>0.01, then regulate control point, each source coordinate height value according to formula (15), obtain new height value NMz _i, substitute former height value and Mz by new height value _i=NMz _i, obtain three-dimensional source control point set MFromPoints={ (Mx _i, My _i, Mz _i) | i=1,2 ... m*n},

$\left\{\begin{array}{cc}{\mathrm{NMz}}_i\&Element;({{\mathrm{Mz}}_i}^{\&prime;}/2,(nonlinear/{\mathrm{accuracy}}_2)*{{\mathrm{Mz}}_i}^{\&prime;})& if(nonlinear/{\mathrm{accuracy}}_2>1)\\ {\mathrm{NMz}}_i\&Element;\left(\right(nonlinear/{\mathrm{accuracy}}_2)*{{\mathrm{Mz}}_i}^{\&prime;}/2,{{\mathrm{Mz}}_i}^{\&prime;})& if(nonlinear/{\mathrm{accuracy}}_2<1)\end{array}\right.---\left(15\right)$

145) circulation step 142)-144), until | nonlinear/accuracy ₂-1|<=0.01, obtains final argument j ₀', j ₁', j ₂', j ₃', j ₄' and j ₅';

Step 15, focal distance f, flying height H, drift angle inclination angle ω, swing angle κ, data center point coordinates (x _mid, y _mid), parameter j ₀', j ₁', j ₂', j ₃', j ₄' and j ₅' composition key K ey, with rivest, shamir, adelman RSA key K ey to be encrypted and stored in key file Key.txt;

(2) DecryptDecryption process

Step 21, reads key file Key.txt, extracts key K ey, open original vector data V after deciphering;

Step 22, generates each point height value z _j, converted coordinate, concrete steps are as follows:

221) extract the key element point coordinates of vector data V, obtain key element point coordinates set P={ (x _j, y _j, z _j) | j=1,2 ..., k}, wherein k is the some number that key element comprises,

222) according to each point coordinates p in key K ey and formula (16) cycle calculations set P _j(x _j, y _j, z _j) height value z _jand be saved in set P,

z _j＝j ₀’+j ₁’x _j+j ₂’y _j+j ₃’x _j ²+j ₄’y _j ²+j ₅’x _jy _j(16)

223) according to formula (17) and key K ey, to each point coordinates p _j(x _j, y _j, z _j) calculate, obtain point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k};

Step 23, Unitary coordinate, according to key K ey and formula (18) to each point coordinates p _j' (x _j', y _j', z _j) be normalized obtain point coordinates set P after DecryptDecryption "={ (x _j", y _j", z _j) | j=1,2 ..., k};

$\left\{\begin{array}{c}{x_j}^{\&prime;\&prime;}=x_{mid}+{x_j}^{\&prime;}*H/f\\ {y_j}^{\&prime;\&prime;}=y_{mid}+{y_j}^{\&prime;}*H/f\end{array}\right.---\left(18\right)$

Step 24, circulation step 22 to 23, until each key element is disposed, preserves the vector data W after DecryptDecryption;

(3) recovery process

Step 31, reads key file Key.txt, extracts key K ey, open the vector data W after DecryptDecryption after deciphering;

Step 32, Unitary coordinate, concrete steps are as follows:

321) extract the key element point coordinates of vector data W, obtain coordinate set WP "={ (wx _j", wy _j", wz _j) | j=1,2 ..., k},

322) according to key K ey and formula (19), to set WP " set in each point coordinates wp _j" (wx _j", wy _j", wz _j) be normalized generation point coordinates set WP '={ (wx _j', wy _j', wz _j) | j=1,2 ..., k}};

$\left\{\begin{array}{c}{{\mathrm{wx}}_j}^{\&prime;}=({{\mathrm{wx}}_j}^{\&prime;\&prime;}-x_{mid})*f/H\\ {{\mathrm{wy}}_j}^{\&prime;}=({{\mathrm{wy}}_j}^{\&prime;\&prime;}-y_{mid})*f/H\end{array}\right.---\left(19\right)$

Step 33, converted coordinate, according to formula (20) and key K ey to each point coordinates wp _j' (wx _j', wy _j', wz _j) calculate, then by height value wz _jzero setting, the point coordinates wp after being restored _j(wx _j, wy _j, 0), generate coordinate set WP={ (wx _j, wy _j, 0) | j=1,2 ..., k};

$\left\{\begin{array}{c}{\mathrm{wx}}_j=x_{mid}+\frac{({\mathrm{wz}}_j-H)(\mathrm{\&omega;}f\mathrm{\&kappa;}-f\mathrm{\&phi;}-{\mathrm{\&omega;}}^2{{\mathrm{wx}}_j}^{\&prime;}-{{\mathrm{wx}}_j}^{\&prime;}+{{\mathrm{\&phi;\&omega;wy}}_j}^{\&prime;}+{{\mathrm{\&kappa;wy}}_j}^{\&prime;})}{({\mathrm{f\&kappa;}}^2-{{\mathrm{\&omega;wy}}_j}^{\&prime;}-{{\mathrm{\&phi;wx}}_j}^{\&prime;}+f-{{\mathrm{\&omega;\&kappa;wx}}_j}^{\&prime;}+{{\mathrm{\&phi;\&kappa;wy}}_j}^{\&prime;})}\\ {\mathrm{wy}}_j=y_{mid}+\frac{({\mathrm{wz}}_j-H)({{\mathrm{\&omega;\&phi;wx}}_j}^{\&prime;}-{\mathrm{\&phi;}}^2{{\mathrm{wy}}_j}^{\&prime;}-{{\mathrm{wy}}_j}^{\&prime;}-f\mathrm{\&omega;}-{{\mathrm{\&kappa;wx}}_j}^{\&prime;}-\mathrm{\&phi;}f\mathrm{\&kappa;})}{({\mathrm{f\&kappa;}}^2-{{\mathrm{\&omega;wy}}_j}^{\&prime;}-{{\mathrm{\&phi;wx}}_j}^{\&prime;}+f-{{\mathrm{\&omega;\&kappa;wx}}_j}^{\&prime;}+{{\mathrm{\&phi;\&kappa;wy}}_j}^{\&prime;})}\end{array}\right.---\left(20\right)$

Step 34, circulation step 32 to 33, until each key element is disposed, the vector data Q after saving/restoring.