CN103067159A - Geographic information system (GIS) vector data reversible decryption method - Google Patents

Abstract

The invention discloses a geographic information system (GIS) vector data reversible decryption method, and belongs to the field of geographic information safety. The method includes a secret key generating process, a decryption process and a recovering process, wherein the secret key generating process includes that a data range is confirmed, data conversion quantity is confirmed, mean square errors caused by linear conversion quantity are calculated, parameters are confirmed, mean square errors caused by non-linear conversion quantity are calculated, parameters are confirmed, and the secret key is encrypted through an asymmetric cryptographic algorithm RSA and is stored in a secret key file. The decryption process includes that the secret key file is read, deciphering is conducted and the secret key is extracted, original vector data are opened, an element point coordinate set is obtained, coordinates are normalized, and circulation process is conducted. The GIS vector data reversible decryption method has the advantages of randomness, gradual change, reversibility and the like, improves reliability of GIS vector data decryption, perfects the geographic information safety protection theory and method system, and can be used for public announcement of the GIS vector data and other aspect.

Description

The reversible DecryptDecryption method of a kind of GIS vector data

Technical field

The invention belongs to the geography information security fields, be specifically related to a kind of reversible DecryptDecryption method for the GIS vector data.

Background technology

The mapping geography information is concerning expanding development space, concerning national security.Especially under the main trend of global IT application, geography information safeguard protection problem is more and more outstanding.Vector data has the characteristics such as precision height, output quality is good, data volume is little, uses very extensively, and its safeguard protection research is very important.

According to national relevant laws and regulations, vector data openly uses to be needed to process through DecryptDecryption, and DecryptDecryption comprises spatial accuracy DecryptDecryption and two aspects of attribute DecryptDecryption.The spatial accuracy DecryptDecryption uses professional DecryptDecryption technology to carry out the displacement of key element, reduces its precision, and the data behind the DecryptDecryption are not having to be difficult for recovery in the situation of key.Spatial accuracy DecryptDecryption method commonly used comprises projection transformation approach, spatial alternation method, random error interference method etc. at present.The projection transformation approach is reversible; The data space converter technique comprises similarity transformation, affine transformation and projective transformation etc., and these several transform methods are linear transformations, is easy to recover the poor reliability that DecryptDecryption is processed; There are the shortcomings such as the topological relation that can not guarantee key element or algorithm be irreversible in meeting that the random error interference method has.

Summary of the invention

The present invention is directed to the defective that existing DecryptDecryption method exists, provide a kind of non-linear mixed model that vector data is carried out the method that DecryptDecryption is processed, have randomness, the element relationship of error Topological, algorithm invertibity and the characteristics such as be difficult to crack.

The reversible DecryptDecryption method of a kind of GIS vector data take the line chart layer as example, comprises following process:

(1) key generative process

Step 11, the specified data scope: obtain the minimum boundary rectangle R of original vector data V, R lower left corner coordinate is (x _Min, y _Min), upper right corner coordinate is (x _Max, y _Max), get 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, the specified data converted quantity: concrete steps are as follows: input data global transformation amount 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 is calculated the middle error that linear transformation amount linear causes, determines to affect the parameter of 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) calculate flying height H according to formula (3),

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

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

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

D) generate the control point set, concrete steps are as follows: generate the individual even control point of m*n (m*n＞=6) and form control point, source set FromPoints={ (Fx in minimum boundary rectangle R scope _i, Fy _i) | i=1,2 ... m*n}; Calculate each target control point coordinates (Tx according to formula (5) _i, Ty _i) composition target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

$\left\{\begin{array}{c}{\mathrm{Tx}}_i={\mathrm{Fx}}_i+{\mathrm{<figure-callout\; id="1"\; label="dir"\; filenames="HDA00002673299400022.png"\; state="\{\{state\}\}">dir</figure-callout>}}_1\&times;\mathrm{linear}+{\mathrm{random}}_1\&times;\mathrm{linearExtent}\\ {\mathrm{Ty}}_i={\mathrm{Fy}}_i+{\mathrm{dir}}_2\&times;\mathrm{linear}+{\mathrm{random}}_2\&times;\mathrm{linearExtent}\end{array}\right.---\left(5\right)$

Wherein: directioin parameter dir ₁In [0.0,1.0] scope, directioin parameter

Perturbation of control points parameter random ₁And random ₂In [1.0,1.0] scope, choose at random,

E) Unitary coordinate is gathered ToPoints according to formula (6) to control point, source set FromPoints and target control point and is carried out normalized and obtain new coordinate set FromPoints '={ (Fx _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) calculate the drift angle

Inclination angle ω, swing angle κ utilize least square method that target control point among FromPoints ' Zhong Yuan control point and the ToPoints ' is carried out match according to formula (7) and resolve and obtain the drift angle

Inclination angle ω, swing angle κ,

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

According to error accuracy1 in formula (9) calculating,

${\mathrm{<figure-callout\; id="1"\; label="accuracy"\; filenames="HDA00002673299400022.png"\; state="\{\{state\}\}">accuracy</figure-callout>}}_1=\sqrt{\mathrm{\&Sigma;}({({{\mathrm{Tx}}_i}^{\&prime;\&prime;}-{\mathrm{Fx}}_i)}^2+{({{\mathrm{Ty}}_i}^{\&prime;\&prime;}-{\mathrm{Fy}}_i)}^2)/(m*n)}---\left(9\right)$

H) regulate the set of target control point, concrete steps are as follows: if | linear/accuracy ₁Each former target control point coordinates (Tx is then regulated according to formula (10) in-1|＞0.01 _i, Ty _i), obtain new target control point coordinates (NTx _i, NTy _i), substituting former target control point with new target control point is Tx _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 is calculated the middle error that nonlinear transformation amount nonlinear causes, determines parameter j ₀-j ₅, concrete steps are as follows:

B) generate the control point elevation, utilize formula (11) to calculate the required elevation Fz of each some displacement nonlinear of control point, source set FromPoints _i, control point, generating three-dimensional source 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) according to formula (12) the three-dimensional source control point set FromPoints that generates is carried out least square and 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) calculate error accuracy in the nonlinear transformation ₂, concrete steps are as follows: according to formula (12) and parameter j ₀-j ₅Resolve the Fz at each control point, source _iValue is saved among the three-dimensional source control point set FromPoints, according to formula (13) three-dimensional source control point set FromPoints is calculated target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

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

According to error accuracy in formula (14) calculating 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) regulate control point, source height value, if | nonlinear/accuracy ₂Each control point, source coordinate height value is then regulated according to formula (15) in-1|＞0.01, obtains new height value NFzi, and substituting former height value with new height value is Fzi=NFzi, obtains 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, the point coordinates (x of data center _Mid, y _Mid), parameter j ₀-j ₅Form key K ey, with rivest, shamir, adelman RSA key K ey is encrypted and deposits in key file Key.txt;

(2) DecryptDecryption process

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

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

A) the key element point coordinates of extraction vector data V obtains 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 among key K ey and formula (16) the cycle calculations set P _j(x _j, y _j, z _j) height value z _jAnd be saved among the 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) carry out normalized and obtain point coordinates set P behind the 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 is until each key element is disposed the data file W behind the preservation DecryptDecryption;

(3) recovery process

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

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

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

B) according to key K ey and formula (19), pair set P " set in each point coordinates p _j" (x _j", y _j", z _j) carry out normalized and generate 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 with 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 is until each key element is disposed the data file Q behind the saving/restoring.

The present invention proposes a kind of non-linear mixed model the GIS vector data is carried out DecryptDecryption and Recovery processing.This method is guaranteeing can to carry out DecryptDecryption to data according to key under the prerequisite that the vector data topological relation does not change for the safeguard protection problem of GIS vector data, and the data behind the DecryptDecryption can be carried out Distortionless according to key.This method has the characteristics such as randomness, gradually changeable, invertibity, has improved the reliability of GIS vector data DecryptDecryption, and perfect theory and the method system of geography information safeguard protection can be used for the aspects such as publishing of GIS vector data.

Description of drawings

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 invention is selected.

Fig. 4 is the design sketch of vector data stack behind initial data of the present invention and the DecryptDecryption.

Embodiment

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

Present embodiment is selected shp form vector data, to data read, DecryptDecryption and recovery operation, further describe the present invention.Present embodiment selects the shp line chart layer data (such as Fig. 3) of a certain building as original vector data, may further comprise the steps:

(1) key generative process

Step 11, specified data scope: the minimum boundary rectangle R that obtains original vector data V, R lower left corner coordinate is (123451.63676768,142705.11870332), upper right corner coordinate is (123726.302067681,142994.494303319), get data center point coordinate (123588.969417681,142849.80650332), data length XL=274.665300000459 and data width YL=289.375599998981 according to formula (1);

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

Step 13 is calculated the middle error that linear transformation amount linear causes, determines to affect the parameter of 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) calculate flying height H=1879.49681193348 according to formula (3),

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

D) generate the control point set, concrete steps are as follows: generate 4*4 even control point and form control point, source set FromPoints={ (Fx in minimum boundary rectangle R scope _i, Fy _i) | i=1,2 ... 4*4}; Calculate each target control point coordinates (Tx 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 gathered ToPoints according to formula (6) to control point, source set FromPoints and target control point and is carried out normalized and obtain new coordinate set FromPoints '={ (Fx _i', Fy _i') | i=1,2 ... 4*4}, ToPoints '={ (Tx _i', Ty _i') | i=1,2 ... 4*4},

F) calculate the drift angle

Inclination angle ω, swing angle κ utilize least square method that target control point among FromPoints ' Zhong Yuan control point and the ToPoints ' is carried out match according to formula (7) and resolve and obtain the drift angle

Inclination angle ω=0.00921638185358357, swing angle κ=0.0206308078601073,

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

H) regulate the set of target control point, concrete steps are as follows: if | linear/accuracy ₁Each former target control point coordinates (Tx is then regulated according to formula (10) in-1|＞0.01 _i, Ty _i), obtain new target control point coordinates (NTx _i, NTy _i), substituting former target control point with new target control point is Tx _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 ₁=49.5075776592392 o'clock | linear/accuracy ₁-1|＜=0.01 obtains final drift angle

Inclination angle ω=0.00901382354283439, swing angle κ=0.0201770830635741;

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

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

B) according to formula (12) the three-dimensional source control point set FromPoints that generates is carried out least square and 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) calculate error accuracy in the nonlinear transformation ₂, concrete steps are as follows: according to formula (12) and parameter j ₀-j ₅Resolve the Fz at each control point, source _iValue is saved among the three-dimensional source control point set FromPoints, according to formula (13) three-dimensional source control point set FromPoints is calculated target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... 4*4}, according to error accuracy in formula (14) calculating ₂=8.33449148774509,

D) regulate control point, source height value, if | nonlinear/accuracy ₂Each control point, source coordinate height value is then regulated according to formula (15) in-1|＞0.01, obtains new height value NFzi, and substituting former height value with new height value is Fzi=NFzi, obtains 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 ₂=6.9961779687363 o'clock | 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, the point coordinates (x of data center _Mid, y _Mid), parameter j ₀-j ₅Form key K ey, with rivest, shamir, adelman RSA key K ey is encrypted and deposits in key file Key.txt;

(2) DecryptDecryption process

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

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

A) the key element point coordinates of extraction vector data V obtains 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, the below with 1 p (123677.937667681,142928.252103319,0) among the P for example describes,

B) according to each point coordinates p among key K ey and formula (16) the cycle calculations set P _j(x _j, y _j, z _j) height value z _jAnd be saved among the 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) conversion after point coordinates be 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) carry out normalized and obtain point coordinates set P behind the DecryptDecryption "={ (x _j", y _j", z _j) | j=1,2 ..., k}, point coordinates is p after the some p ' normalization " (123639.34343161,142914.631440834,119.892017556354);

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

(3) recovery process

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

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

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

B) according to key K ey and formula (19), pair set P " set in each point coordinates p _j" (x _j", y _j", z _j) carry out normalized and generate point coordinates set P '={ (x _j', y _j', z _j) | j=1,2 ..., k} is to example points p " carry out 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 with 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}, the point coordinates after conversion p ' coordinate is restored is p (123677.937667681,142928.252103319,0);

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

Only carry out DecryptDecryption and the recovery of vector data in the embodiment of the invention as an example of the line chart layer example, the method also can be used for DecryptDecryption and the recovery of point diagram layer and face figure layer.

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

Claims (1)

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

(1) key generative process

Step 11, the specified data scope: obtain the minimum boundary rectangle R of original vector data V, R lower left corner coordinate is (x _Min, y _Min), upper right corner coordinate is (x _Max, y _Max), get 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, the specified data converted quantity: concrete steps are as follows: input data global transformation amount 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 is calculated the middle error that linear transformation amount linear causes, determines to affect the parameter of transform effect: focal distance f, flying height H, drift angle

Inclination angle ω, swing angle κ, concrete steps are as follows:

A) focal distance f ∈ (0,1),

B) calculate flying height H according to formula (3),

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

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

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

D) generate the control point set, concrete steps are as follows: generate m*n even control point and form control point, source set FromPoints={ (Fx in minimum boundary rectangle R scope _i, Fy _i) | i=1,2 ... m*n}, m*n＞=6; Calculate each target control point coordinates (Tx 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 ₂In [1.0,1.0] scope, choose at random,

E) Unitary coordinate is gathered ToPoints according to formula (6) to control point, source set FromPoints and target control point and is carried out normalized and obtain new coordinate set FromPoints '={ (Fx _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) calculate the drift angle

Inclination angle ω, swing angle κ utilize least square method that target control point among FromPoints ' Zhong Yuan control point and the ToPoints ' is carried out match according to formula (7) and resolve and obtain the drift angle

Inclination angle ω, swing angle κ,

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

According to error accuracy in formula (9) calculating ₁,

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

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

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

I) circulation step e)-h) until | linear/accuracy ₁-1|＜=0.01 obtains final drift angle

Inclination angle ω, swing angle κ;

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

A) generate the control point elevation, utilize formula (11) to calculate the required elevation Fz of each some displacement nonlinear of control point, source set FromPoints _i, control point, generating three-dimensional source 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) according to formula (12) the three-dimensional source control point set FromPoints that generates is carried out least square and 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) calculate error accuracy in the nonlinear transformation ₂, concrete steps are as follows: according to formula (12) and parameter j ₀-j ₅Resolve the Fz at each control point, source _iValue is saved among the three-dimensional source control point set FromPoints, according to formula (13) three-dimensional source control point set FromPoints is calculated target control point set ToPoints={ (Tx _i, Ty _i) | i=1,2 ... m*n},

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

According to error accuracy in formula (14) calculating 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) regulate control point, source height value, if | nonlinear/accuracy ₂Each control point, source coordinate height value is then regulated according to formula (15) in-1|＞0.01, obtains new height value NFz _i, substituting former height value with new height value is Fz _i=NFz _i, 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, the point coordinates (x of data center _Mid, y _Mid), parameter j ₀-j ₅Form key K ey, with rivest, shamir, adelman RSA key K ey is encrypted and deposits in key file Key.txt;

(2) DecryptDecryption process

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

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

A) the key element point coordinates of extraction vector data V obtains 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 among key K ey and formula (16) the cycle calculations set P _j(x _j, y _j, z _j) height value z _jAnd be saved among the 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) carry out normalized and obtain point coordinates set P behind the 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 is until each key element is disposed the data file W behind the preservation DecryptDecryption;

(3) recovery process

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

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

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

B) according to key K ey and formula (19), pair set P " set in each point coordinates p _j" (x _j", y _j", z _j) carry out normalized and generate 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 with 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 is until each key element is disposed the data file Q behind the saving/restoring.

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