CN104599224A - Point type GIS (Geographic Information System) vector data disguising and recovery method based on information divided storage - Google Patents

Abstract

The invention discloses a point type GIS vector data disguising and recovery method based on information divided storage. The method includes the steps of (1) a point type GIS vector data disguising process: determination of the scope of disguising, generation of disguising points and the like; (2) a point type GIS vector data recovery process: identification of disguising targets, reduction of the disguising points and the like. The point type GIS vector data disguising and recovery method based on information divided storage has the advantages of being high in hidden performance and free from capacity constraints, provides a new idea for vector geographic data information disguising and effectively protects the security of confidential point data in data transmission and hidden communication on the basis of hiding the existence of secret information.

Description

A kind of based on information divide deposit concerning security matters point-like geographic element camouflage and method of reducing

Technical field

The invention belongs to field of geographic information safety, be specifically related to a kind of based on information the GIS vector data camouflage dividing the technology of depositing to carry out vertex type and the method for reducing.

Background technology

The security protection of geography information relates to national security and social benefit, is the current great needs of problems of country and society being badly in need of solving.On the basis hidden the secret GIS vector data information content, hiding the existence of secret information further, is the emphasis of current geographic information security study and application.

At present, information divides the technology of depositing to be mainly used in image domains, image divides the implication of depositing to be image information is divided into the n width image with certain visual effect, if know m (m<n) the width subimage in image information, then this image can be restored, if image is less than m width, then image cannot be restored.Use for reference to divide and deposit the application of technology at image domains, the technology of depositing will be divided to be applied to vector geographic data information disguising, adopt certain method to divide in the vector geographic data of depositing multiple dispersion complete vector geographic data to pretend, make the data after camouflage remain significant vector geographic data.Compared with existing camouflage method, both taken into account the concealed advantage of precision crippled mode, turn avoid scrambled fashion easily cause assailant to note and carrier Stealth Modus to defects such as the high requests of capacity.

Summary of the invention

The object of the invention is to: divide based on information and deposit camouflage, propose a kind of camouflage for concerning security matters point-like geographic element in GIS point diagram layer data and method of reducing, can the security of effective guarantee concerning security matters point data in data transmission, Communication hiding.

To achieve these goals, the technical scheme that the present invention takes mainly comprises:

Divide the camouflage of concerning security matters point-like geographic element and a method of reducing of depositing based on information, concrete steps are as follows:

(1) the pseudo-process of assembling of vertex type GIS vector data

Step 11: load a width point layer map vector, and input camouflage radius factor c, c ∈ (0,1);

Step 12: select concerning security matters point set P={P from original point figure layer data R _i| i=1,2 ..., m}, m are the number of concerning security matters point; For each the concerning security matters point P in point set P _i, circulation performs step 13 to step 17 successively;

Step 13: determine current concerning security matters point P _iintend generating the leg-of-mutton interior angle of camouflage _i1, α _i2, α _i3,

A () adopts recurrence growth method to the triangulation network set T of current point layer data genaration TIN data layout, from set T, traversal comprises current concerning security matters point P _itriangle sets T'={T _j' | j=1,2 ..., n}, wherein T' ∈ T, n are for comprising P _ileg-of-mutton number;

B () is to three interior angle of set T' intermediate cam shape _i1, α _i2, α _i3sort from small to large, and angularly sequentially leave in set A 1, A2, A3 successively from small to large, wherein A1={A1 _j| j=1,2 ..., n}, A2={A2 _j| j=1,2 ..., n}, A3={A3 _j| j=1,2 ..., n}, wherein n is leg-of-mutton number;

(c) based on formula (1) to set A 1, A2, A3 average respectively can obtain pretend leg-of-mutton three interior angle _i1, α _i2, α _i3:

$\left\{\begin{array}{c}{\mathrm{\&alpha;}}_{i1}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A1}_j}{n}\\ {\mathrm{\&alpha;}}_{i2}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A2}_j}{n}\\ {\mathrm{\&alpha;}}_{i3}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A3}_j}{n}\end{array}\right.---\left(1\right)$

Step 14: determine current concerning security matters point P _icamouflage radius r _i',

A () calculates the leg-of-mutton interior angle ratio of camouflage intending generating according to formula (2), be designated as 1:m:n, wherein n>m>1,

$\left\{\begin{array}{c}m=\frac{{\mathrm{\&alpha;}}_{i2}}{{\mathrm{\&alpha;}}_{i1}}\\ n=\frac{{\mathrm{\&alpha;}}_{i3}}{{\mathrm{\&alpha;}}_{i1}}\end{array}\right.---\left(2\right)$

B () establishes three points intending camouflage generation to be respectively P _i1, P _i2, P _i3, the Thiessen polygon of current concerning security matters point is designated as ABCDEF, and the camouflage center of circle is o, and maximum camouflage radius is r, P _iwith other original point P _jminor increment be R, j ≠ i, P _i1p _i2distance maximal value is designated as l, P _i1point and P _iminor increment be designated as l _i; According to the structure rule of TIN, guaranteeing that intending puppet decorates under same leg-of-mutton prerequisite, obtains the maximum camouflage radius r of current concerning security matters point based on formula (3) _i:

$\left\{\begin{array}{c}l=2*\sin \left(\frac{\mathrm{\&pi;n}}{1+m+n}\right)r_i\\ R=\mathrm{MIN}\left(\right|P_j{P}_i\left|\right),(j\&NotEqual;i)\\ l_i=R-r_i\\ r_i<\frac{R}{2*\sin \left(\frac{\mathrm{\&pi;n}}{1+m+n}\right)+1}\end{array}\right.---\left(3\right)$

C () calculates the camouflage radius r of current concerning security matters point according to formula (4) _i', wherein, c is customer parameter:

r _i'＝c*r _i,c∈(0,1) (4)

Step 15: the calculating intending camouflage point coordinate value, current concerning security matters point P _icoordinate is designated as (x _i, y _i),

A central angle that () pretends each limit of triangle corresponding is designated as β successively according to order from small to large ₁, β ₂, β ₃, computing formula is as shown in (5):

$\left\{\begin{array}{c}{\mathrm{\&beta;}}_1=\frac{2\mathrm{\&pi;}}{1+m+n}\\ {\mathrm{\&beta;}}_2=\frac{2\mathrm{\&pi;m}}{1+m+n}\\ {\mathrm{\&beta;}}_3=\frac{2\mathrm{\&pi;n}}{(1+m+n)}\end{array}\right.---\left(5\right)$

B () first puppet is decorateeed: get arbitrarily on camouflage circle and a bit decorate P as first puppet _i1(x _i1, y _i1), as shown in formula (6):

$\left\{\begin{array}{c}{x}_{i1}=\mathrm{random}[x_i-{r_i}^{\&prime;},x_i+{r_i}^{\&prime;}]\\ y_{i1}=y_i\&PlusMinus;\sqrt{{r_i}^{\&prime;2}-{(x_{i1}-x_i)}^2}\end{array}\right.---\left(6\right)$

C () second puppet decorates P _i2(x _i2, y _i2), suppose P _i2with P _i1the central angle that the chord length of formation is corresponding is β ₁, based on P _i1rotate β in the direction of the clock ₁, P _i2coordinate computing formula as shown in (7):

$\left\{\begin{array}{c}{x}_{i2}=(x_{i1}-x_i)\cos {\mathrm{\&beta;}}_1-(y_{i1}-y_i)\sin {\mathrm{\&beta;}}_1+x_i\\ y_{i2}=(y_{i1}-y_i)\cos {\mathrm{\&beta;}}_1+(x_{i1}-x_i)\sin {\mathrm{\&beta;}}_1+y_i\end{array}\right.---\left(7\right)$

D () the 3rd puppet decorates P _i3(x _i3, y _i3): according to the structure of TIN triangulation network rule and pretend leg-of-mutton interior angle and decorate than for 1:m:n two conditions traversal the 3rd puppet on camouflage circle, according to counterclockwise the 3rd puppet being found to decorate, computing formula is as shown in (8):

$\left\{\begin{array}{c}{x}_{i3}=(x_{i1}-x_i)\cos {\mathrm{\&beta;}}_2+(y_{i1}-y_i)\sin {\mathrm{\&beta;}}_2+x_i\\ y_{i3}=(y_{i1}-y_i)\cos {\mathrm{\&beta;}}_2-(x_{i1}-x_i)\sin {\mathrm{\&beta;}}_2+y_i\end{array}\right.---\left(8\right)$

Step 16: three puppets generated are decorateeed P _i1, P _i2, P _i3substitute current concerning security matters point P _ibe updated in original point figure layer data R;

Step 17: by current concerning security matters point P _icamouflage radius r _i' do enciphering transformation after the key information k that generates _iadd in key file KeyFile;

Step 18: repeat step 13 to step 17, until realize the camouflage process to each concerning security matters point key element, the data file of preserving after camouflage is R';

(2) for vertex type GIS vector data reduction process

Step 21: open the data file R' after camouflage, opens key file KeyFile; For each concerning security matters point P _ireduction, successively circulation perform step 22 to step 26:

Step 22: the triangulation network set T vector point diagram layer data after current camouflage being built to TIN data layout according to recurrence growth method;

Step 23: to camouflage triangle S _iidentification, the triangle formed by three points after pretending in triangulation network set T is called camouflage triangle;

A () reads current i-th group key k in key file KeyFile _i, after deciphering reduction, current camouflage triangle S can be obtained _icircumradius r _i';

B () asks its circumscribed circle center of circle O to each triangle in set T _icoordinate (x _i, y _i), remember that each Atria apex coordinate is respectively P _i1(x _i1, y _i1), P _i2(x _i2, y _i2), P _i3(x _i3, y _i3), computing formula is as shown in (9); At known circumscribed circle center of circle O _ion the basis of coordinate, calculate circumradius r according to formula (10) _i:

$\left\{\begin{array}{c}{x}_i=\frac{({x_{i1}}^2-{x_{i2}}^2+{y_{i1}}^2-{y_{i2}}^2)*(y_{i1}-y_{i3})-({x_{i1}}^2-{x_{i3}}^2+{y_{i1}}^2-{y_{i3}}^2)*(y_{i1}-y_{i2})}{2*(y_{i1}-y_{i3})*(x_{i1}-x_{i2})-2*(y_{i1}-y_{i2})*(x_{i1}-x_{i3})}\\ y_i=\frac{({x_{i1}}^2-{x_{i2}}^2+{y_{i1}}^2-{y_{i2}}^2)*(x_{i1}-x_{i3})-({x_{i1}}^2-{x_{i3}}^2+{y_{i1}}^2-{y_{i3}}^2)*(x_{i1}-x_{i2})}{2*(y_{i1}-y_{i2})*(x_{i1}-x_{i3})-2*(y_{i1}-y_{i3})*(x_{i1}-x_{i2})}\end{array}\right.---\left(9\right)$

$r_i=\sqrt{{(x_{i1}-x_i)}^2+{(y_{i1}-y_i)}^2}---\left(10\right)$

C each triangle in () traversal T, searches its circumradius r _iwith r _i' equal all triangles, be designated as set A={ A _i| i=1,2 ..., n}, wherein n is the triangle number meeting this condition;

If d () n is 1, so this triangle is camouflage triangle S _i, these leg-of-mutton three summits are puppet and decorate; If n is greater than 1, then proceed to step (e);

E () pretends triangle S according to interior angle than screening further _i; To current triangle A _icirculation performs following operation successively:

I () calculates current triangle A respectively _ithree interior angles, and be designated as α respectively according to order from small to large _i1, α _i2, α _i3;

(ii) ephemeral data R is created _tmp, and by data file R' assignment to data R _tmp;

(iii) by current triangle A _icorresponding circumscribed circle center of circle O _ireplace these leg-of-mutton three vertex updates to ephemeral data R _tmpin, regenerate the triangulation network set T' of TIN data layout;

(iV) in set T', traversal comprises O _ithe triangle sets B={B of point _i| i=1,2 ..., m}, m are for comprising O _ithe triangle number of point; According to the rule of described step 13, average internal angle value is tried to achieve for all triangles in set B, and is designated as β successively by order from small to large ₁, β ₂, β ₃;

(V) if interior angle mean value β ₁, β ₂, β ₃with α _i1, α _i2, α _i3equal respectively, so current triangle A _ifor camouflage triangle; If interior angle mean value β ₁, β ₂, β ₃with α _i1, α _i2, α _i3not etc., circulation performs step (i) to (V), until traverse qualified camouflage triangle;

Step 24: camouflaged target reduces, travels through the camouflage triangle S obtained _ithree vertex point coordinates be respectively P _i1, P _i2, P _i3, original concerning security matters point coordinate P can be calculated by formula (9) _i(x _i, y _i);

Step 25: by the original concerning security matters point coordinate P after reduction _ialternative puppet decorates P _i1, P _i2, P _i3be updated in vector data file R';

Step 26: repeat step 22-25, complete the reduction treatment of each concerning security matters point successively.

To divide in the vertex type GIS vector data camouflage method deposited based on information, when calculating second puppet is decorateeed, in theory based on P for above-mentioned _i1by counterclockwise rotating β ₁same to be suitable for, but according to the structure rule of the TIN triangulation network and pretend leg-of-mutton three interior angles than being 1:m:n, to travel through and decorateeing less than the 3rd puppet.Therefore second puppet is decorateeed and can only be calculated according to clockwise direction.

The present invention utilizes information to divide the technology of depositing, and by being deposited in multiple vectorial geographical point data by each concerning security matters point element information minute, reaches the effect of camouflage.The method morphologically keeps global coherency by making the triangulation network after camouflage and the original triangulation network, reduce the notice of assailant, improve the disguise of camouflage, and can avoid the problem that in conventional camouflage, embedding capacity is too low, the communication that can meet GIS vector data is to a certain extent hidden and safe transmission demand.Method of the present invention has higher disguise and is not subject to the advantage of capacity limit, for the information disguising of vector geographic data provides new approaches, the security of the secret point data of effective guarantee in data transmission, Communication hiding on the basis of hiding secret information existence.

Accompanying drawing explanation

Fig. 1 is the process flow diagram of the inventive method, and (a) is camouflage process flow diagram, and (b) is reduction process flow diagram;

Fig. 2 is the camouflage scope schematic diagram of the inventive method;

Fig. 3 is that three puppets of the inventive method decorate schematic diagram, and (a) is that second puppet decorates schematic diagram, and (b) is that the 3rd puppet decorates schematic diagram, and (c) is that three puppets decorate schematic diagram.

Fig. 4 is raw data of the present invention and Camouflaged data TIN comparison diagram, a () is raw data triangulation network schematic diagram, wherein the point of overstriking is that puppet is decorateeed, b () is data triangulation network schematic diagram after camouflage, wherein the point of overstriking is concerning security matters points, and the point on circle is that three puppets are decorateeed.

Fig. 5 is raw data of the present invention and Camouflaged data comparison diagram, (a) raw data schematic diagram, and the point of wherein overstriking is original concerning security matters points, and (b) is schematic diagram data after camouflage, and the point of wherein overstriking is that the puppet generated is decorateeed.

Embodiment

The present embodiment selects shp form vector data, for the whole process of the reading of data, camouflage, reduction, further describes the present invention.This example selects certain simulation concerning security matters point shp data to be experimental data.

(1) pseudo-process of assembling

Step 11: loading simulation concerning security matters point shp data, and input c=0.5 as initial key parameter.

Step 12: select concerning security matters point set P={ (813.91989999999987 ,-1033.2102999999997) }.

Step 13: determine that current concerning security matters point is intended generating the leg-of-mutton interior angle of camouflage _i1, α _i2, α _i3.

A (), to current point layer data genaration triangulation network T, has 4 triangles to comprise concerning security matters point in set T;

B () three interior angles to set T ' intermediate cam shape sort from small to large, and angularly sequentially leave in successively in A1, A2, A3 from small to large, wherein A1={24.336498184787121,13.579427824944508,18.623653496634297,56.170816586114064}, A2={55.463665017116085,19.117895793786708,46.434232690564436,57.765929283815957}, A3={100.1998367980968,147.30267638126884,114.94211381280124,66.063254130069978};

(c) based on formula (1) to A1, A2, A3 respectively averaging can obtain pretend leg-of-mutton three interior angle a ₁=28.177599023119996, a ₂=44.6954306963208, a ₃=107.12697028055921.

Step 14: determine current concerning security matters point P _iactual camouflage radius r _i1.

A () calculates the leg-of-mutton interior angle ratio of camouflage intending generating according to formula (2), be 1:1.5862043696358856:3.801848773298977.

B () as shown in Figure 2, obtains the maximum camouflage radius r of current concerning security matters point based on formula (3) ₁=88.307168093798111.

C () calculates the actual camouflage radius r of current concerning security matters point according to formula (4) ₁₁=44.153584046899056.

Step 15: the calculating intending camouflage point coordinate value.

A) (a) calculates central angle according to formula (5) and can obtain 28.177599023119996,44.6954306963208,107.12697028055921.

B () first puppet is decorateeed: according to formula (6), and camouflage circle gets arbitrarily 1 P ₁₁=(825.21531441389641 ,-990.52596332476355).

C () second puppet is decorateeed: can obtain according to computing formula (7).P ₁₂＝(784.64383219137676，-1000.1580559331973)。

D () the 3rd puppet is decorateeed: can obtain P according to computing formula (8) ₁₃=(856.72190907596212 ,-1044.0512871897263).

Step 16: three puppets generated are decorateeed P ₁₁, P ₁₂, P ₁₃replace current concerning security matters point P _istored in original point figure layer data R.

Step 17: the result current puppet decorateeed after the conversion of triangle camouflage radius of circle is added in key file KeyFile.

Step 18: repeat step 13 to step 18, until realize the camouflage process to each concerning security matters point key element, the data file of preserving after camouflage is R'.

(2) reduction process

Step 21: open the vector data R' after camouflage, open key file KeyFile.

Step 22: the triangulation network T vector point diagram layer data R' after current camouflage being built to TIN data layout according to recurrence growth method.

Step 23: the identification of camouflaged target,

A () reads current key in key file KeyFile, can obtain the leg-of-mutton circumradius 44.153584046899056 of current camouflage after deciphering reduction.

B () asks its circumscribed circle central coordinate of circle to triangle each in T.

The triangle number that the c external radius of a circle of T intermediate cam shape that () traverses is equal with current key radius is 1, and this triangle is camouflage triangle.

D () is read leg-of-mutton three apex coordinates of camouflage and is respectively P ₀₁(825.21531441389641 ,-990.52596332476355), P ₀₂(784.64383219137676 ,-1000.1580559331973), P ₀₃(856.72190907596212 ,-1044.0512871897263).

Step 24: camouflaged target reduces, and can obtain P according to formula (9) ₀point coordinate (813.91989999999987 ,-1033.2102999999997).

Step 25: by the coordinate points P after reduction ₀puppet is replaced to decorate P ₀₁, P ₀₂, P ₀₃join in vector data R'.

Step 26: repeat step 22-25, complete every reduction treatment according to the backward pretending dot generation in pseudo-process of assembling successively.

Claims (2)

1. divide the camouflage of concerning security matters point-like geographic element and a method of reducing of depositing based on information, it is characterized in that, concrete steps are as follows:

(1) the pseudo-process of assembling of vertex type GIS vector data

Step 11: load a width point layer map vector, and input camouflage radius factor c, c ∈ (0,1);

Step 12: select concerning security matters point set P={P from original point figure layer data R _i| i=1,2 ..., m}, m are the number of concerning security matters point; For each the concerning security matters point P in point set P _i, circulation performs step 13 to step 17 successively;

Step 13: determine current concerning security matters point P _iintend generating the leg-of-mutton interior angle of camouflage _i1, α _i2, α _i3,

A () adopts recurrence growth method to the triangulation network set T of current point layer data genaration TIN data layout, from set T, traversal comprises current concerning security matters point P _itriangle sets T '={ T _j' | j=1,2 ..., n}, wherein T ' ∈ T, n are for comprising P _ileg-of-mutton number;

B () is to three interior angle of set T ' intermediate cam shape _i1, α _i2, α _i3sort from small to large, and angularly sequentially leave in set A 1, A2, A3 successively from small to large, wherein A1={A1 _j| j=1,2 ..., n}, A2={A2 _j| j=1,2 ..., n}, A3={A3 _j| j=1,2 ..., n}, wherein n is leg-of-mutton number;

(c) based on formula (1) to set A 1, A2, A3 average respectively can obtain pretend leg-of-mutton three interior angle _i1, α _i2, α _i3:

$\left\{\begin{array}{c}{\mathrm{\&alpha;}}_{i1}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A1}_j}{n}\\ {\mathrm{\&alpha;}}_{i2}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A2}_j}{n}\\ {\mathrm{\&alpha;}}_{i3}=\frac{\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{A3}_j}{n}\end{array}\right.---\left(1\right)$

Step 14: determine current concerning security matters point P _icamouflage radius r _i',

A () calculates the leg-of-mutton interior angle ratio of camouflage intending generating according to formula (2), be designated as 1:m:n, wherein n>m>1,

$\left\{\begin{array}{c}m=\frac{{\mathrm{\&alpha;}}_{i2}}{{\mathrm{\&alpha;}}_{i1}}\\ n=\frac{{\mathrm{\&alpha;}}_{i3}}{{\mathrm{\&alpha;}}_{i1}}\end{array}\right.---\left(2\right)$

B () establishes three points intending camouflage generation to be respectively P _i1, P _i2, P _i3, the Thiessen polygon of current concerning security matters point is designated as ABCDEF, and the camouflage center of circle is o, and maximum camouflage radius is r, P _iwith other original point P _jminor increment be R, j ≠ i, P _i1p _i2distance maximal value is designated as l, P _i1point and P _iminor increment be designated as l _i; According to the structure rule of TIN, guaranteeing that intending puppet decorates under same leg-of-mutton prerequisite, obtains the maximum camouflage radius r of current concerning security matters point based on formula (3) _i:

$\left\{\begin{array}{c}l=2*\sin \left(\frac{\mathrm{\&pi;n}}{1+m+n}\right)r_i\\ R=\mathrm{MIN}\left(\right|P_j{P}_i\left|\right),(j\&NotEqual;i)\\ l_i=R-r_i\\ r_i<\frac{R}{2*\sin \left(\frac{\mathrm{\&pi;n}}{1+m+n}\right)+1}\end{array}\right.---\left(3\right)$

C () calculates the camouflage radius r of current concerning security matters point according to formula (4) _i', wherein, c is customer parameter:

r _i′＝c*r _i,c∈(0,1) (4)

Step 15: the calculating intending camouflage point coordinate value, current concerning security matters point P _icoordinate is designated as (x _i, y _i),

A central angle that () pretends each limit of triangle corresponding is designated as β successively according to order from small to large ₁, β ₂, β ₃, computing formula is as shown in (5):

$\left\{\begin{array}{c}{\mathrm{\&beta;}}_1=\frac{2\mathrm{\&pi;}}{1+m+n}\\ {\mathrm{\&beta;}}_2=\frac{2\mathrm{\&pi;m}}{1+m+n}\\ {\mathrm{\&beta;}}_3=\frac{2\mathrm{\&pi;n}}{(1+m+n)}\end{array}\right.---\left(5\right)$

B () first puppet is decorateeed: get arbitrarily on camouflage circle and a bit decorate P as first puppet _i1(x _i1, y _i1), as shown in formula (6):

$\left\{\begin{array}{c}{x}_{i1}=\mathrm{random}[x_i-{r_i}^{\&prime;},x_i+{r_i}^{\&prime;}]\\ y_{i1}=y_i\&PlusMinus;\sqrt{{r_i}^{\&prime;2}-{(x_{i1}-x_i)}^2}\end{array}\right.---\left(6\right)$

C () second puppet decorates P _i2(x _i2, y _i2), suppose P _i2with P _i1the central angle that the chord length of formation is corresponding is β ₁, based on P _i1rotate β in the direction of the clock ₁, P _i2coordinate computing formula as shown in (7):

$\left\{\begin{array}{c}{x}_{i2}=(x_{i1}-x_i)\cos {\mathrm{\&beta;}}_1-(y_{i1}-y_i)\sin {\mathrm{\&beta;}}_1+x_i\\ y_{i2}=(y_{i1}-y_i)\cos {\mathrm{\&beta;}}_1+(x_{i1}-x_i)\sin {\mathrm{\&beta;}}_1+y_i\end{array}\right.---\left(7\right)$

D () the 3rd puppet decorates P _i3(x _i3, y _i3): according to the structure of TIN triangulation network rule and pretend leg-of-mutton interior angle and decorate than for 1:m:n two conditions traversal the 3rd puppet on camouflage circle, according to counterclockwise the 3rd puppet being found to decorate, computing formula is as shown in (8):

$\left\{\begin{array}{c}{x}_{i3}=(x_{i1}-x_i)\cos {\mathrm{\&beta;}}_2+(y_{i1}-y_i)\sin {\mathrm{\&beta;}}_2+x_i\\ y_{i3}=(y_{i1}-y_i)\cos {\mathrm{\&beta;}}_2-(x_{i1}-x_i)\sin {\mathrm{\&beta;}}_2+y_i\end{array}\right.---\left(8\right)$

Step 16: three puppets generated are decorateeed P _i1, P _i2, P _i3substitute current concerning security matters point P _ibe updated in original point figure layer data R;

Step 17: by current concerning security matters point P _icamouflage radius r _i' do enciphering transformation after the key information k that generates _iadd in key file KeyFile;

Step 18: repeat step 13 to step 17, until realize the camouflage process to each concerning security matters point key element, the data file of preserving after camouflage is R ';

(2) for vertex type GIS vector data reduction process

Step 21: open the data file R ' after camouflage, opens key file KeyFile; For each concerning security matters point P _ireduction, successively circulation perform step 22 to step 26:

Step 22: the triangulation network set T vector point diagram layer data after current camouflage being built to TIN data layout according to recurrence growth method;

Step 23: to camouflage triangle S _iidentification, the triangle formed by three points after pretending in triangulation network set T is called camouflage triangle;

A () reads current i-th group key k in key file KeyFile _i, after deciphering reduction, current camouflage triangle S can be obtained _icircumradius r _i';

B () asks its circumscribed circle center of circle O to each triangle in set T _icoordinate (x _i, y _i), remember that each Atria apex coordinate is respectively P _i1(x _i1, y _i1), P _i2(x _i2, y _i2), P _i3(x _i3, y _i3), computing formula is as shown in (9); At known circumscribed circle center of circle O _ion the basis of coordinate, calculate circumradius r according to formula (10) _i:

$\left\{\begin{array}{c}{x}_i=\frac{({x_{i1}}^2-{x_{i2}}^2+{y_{i1}}^2-{y_{i2}}^2)*(y_{i1}-y_{i3})-({x_{i1}}^2-{x_{i3}}^2+{y_{i1}}^2-{y_{i3}}^2)*(y_{i1}-y_{i2})}{2*(y_{i1}-y_{i3})*(x_{i1}-x_{i2})-2*(y_{i1}-y_{i2})*(x_{i1}-x_{i3})}\\ y_i=\frac{({x_{i1}}^2-{x_{i2}}^2+{y_{i1}}^2-{y_{i2}}^2)*(x_{i1}-x_{i3})-({x_{i1}}^2-{x_{i3}}^2+{y_{i1}}^2-{y_{i3}}^2)*(x_{i1}-x_{i2})}{2*(y_{i1}-y_{i2})*(x_{i1}-x_{i3})-2*(y_{i1}-y_{i3})*(x_{i1}-x_{i2})}\end{array}\right.---\left(9\right)$

$r_i=\sqrt{{(x_{i1}-x_i)}^2+{(y_{i1}-y_i)}^2}---\left(10\right)$

C each triangle in () traversal T, searches its circumradius r _iwith r _i' equal all triangles, are designated as set A={ A _i| i=1,2 ..., n}, wherein n is the triangle number meeting this condition;

If d () n is 1, so this triangle is camouflage triangle S _i, these leg-of-mutton three summits are puppet and decorate; If n is greater than 1, then proceed to step (e);

E () pretends triangle S according to interior angle than screening further _i;

Step 24: camouflaged target reduces, travels through the camouflage triangle S obtained _ithree vertex point coordinates be respectively P _i1, P _i2, P _i3, original concerning security matters point coordinate P can be calculated by formula (9) _i(x _i, y _i);

Step 25: by the original concerning security matters point coordinate P after reduction _ialternative puppet decorates P _i1, P _i2, P _i3be updated in vector data file R ';

Step 26: repeat step 22-25, complete the reduction treatment of each concerning security matters point successively.

2. according to claim 1ly a kind ofly divide the camouflage of concerning security matters point-like geographic element and method of reducing of depositing based on information, it is characterized in that, in step 23 (e), further screening camouflage triangle S _idetailed process as follows: to current triangle A _icirculation performs following operation successively:

I () calculates current triangle A respectively _ithree interior angles, and be designated as α respectively according to order from small to large _i1, α _i2, α _i3;

(ii) ephemeral data R is created _tmp, and by data file R ' assignment to data R _tmp;

(iii) by current triangle A _icorresponding circumscribed circle center of circle O _ireplace these leg-of-mutton three vertex updates to ephemeral data R _tmpin, regenerate the triangulation network set T ' of TIN data layout;

(iV) O is comprised in the middle traversal of set T ' _ithe triangle sets B={B of point _i| i=1,2 ..., m}, m are for comprising O _ithe triangle number of point; According to the rule of described step 13, average internal angle value is tried to achieve for all triangles in set B, and is designated as β successively by order from small to large ₁, β ₂, β ₃;

(V) if interior angle mean value β ₁, β ₂, β ₃with α _i1, α _i2, α _i3equal respectively, so current triangle A _ifor camouflage triangle; If interior angle mean value β ₁, β ₂, β ₃with α _i1, α _i2, α _i3not etc., circulation performs step (i) to (V), until traverse qualified camouflage triangle.