CN102779344B - Registering block for space exchange and use method thereof - Google Patents

Abstract

The invention relates to a tag block for space exchange and a vision orientation registering method thereof. The tag block can reduce staff operation errors, improves registering precision, is compatible with various imaging devices and reduces cost of the tag block and orientation. The tag block is structurally characterized in that a cover plate is installed on a base, a vision tag is arranged on the cover plate, and the N-shaped tag block is arranged in the base; and the base is installed on a supporting plate, and imaging substances are filled in the N-shaped tag block. The method includes that (1) conducting imaging processing on the tag block through a perspective imaging device to obtain image body data; locating a middle point of the N-shaped tag block in a body data image, and using the coordinate of the middle point as the body data space coordinate of a tag point; (2) conducting automatic recognition and locating on the vision tag by using a three-dimensional vision locating system, calculating the coordinate of the middle point of the N-shaped tag block, and using the coordinate of the middle point as the vision space coordinate of the tag point; and (3) by means of an affine method or a singular value decomposition method, calculating a space alternation array of a body data image space and a vision space, and finishing registering of the body data space and the vision space.

Description

Registration block and using method thereof for spatial alternation

Technical field

The spatial alternation that the object of the invention is to propose a kind of applicable vision location is by registration block and for the method for volume data space and visual space registration.

Background technology

By visual space and volume data spatial registration, can utilize vision guide to complete the process operation to interior of articles.Conventional spatial registration method has three classes:

1. use special framework to carry out registration.Object is arranged in registration framework, and acquisition volume data, carry out registration by the feature of registration framework, and this method is subject to the restriction of frame size and mounting means, is difficult to adapt to the variation of dimension of object, shape.

2. utilize the geometric properties of object to carry out registration.As utilize the curved surface of body surface formation to carry out registration, and this mode calculated amount is very large, and the registration time is longer.

3. use registration block to carry out registration.At body surface fixed registration piece, be used for, at different space orientation and identification registration features point, utilizing unique point to complete the registration in space.While using registration block registration, need identification, locate the unique point for spatial registration, easy introducing personnel operate miss during still artificial locator piece.

For reducing the registration error of the third method, conventionally adopt registration block automatically to identify the method for location, as adopted spherical labels thing, process the edge that image obtains ball, justify or oval matching, and calculate sphere center position, realize the location of registration block.The matching of edge extracting and circle needs a large amount of calculating; Need 2 width could in volume data space, complete centre of sphere location with the processing of epigraph; In order to justify reliably matching, need to use large-sized spheroid, make registration block volume larger.Also more to the locator meams of registration block in operating space, as electromagnetic type, photo-electric, stereoscopic vision etc.In order to solve the compatibling problem of registration block and volume data imaging device, the registration block that electromagnetism and photoelectric method need to be used certain material to make.

Summary of the invention

Object of the present invention is exactly for the automaticity of raising spatial registration, reduces registration block cost, reduces personnel's operate miss, a kind of registration block and vision locator method thereof for spatial alternation is provided, it utilizes registration block, in different spaces subject to registration, registration features point is carried out to automatic or semi-automatic location to reduce personnel's operate miss, improve registration accuracy, be easy to compatible various imaging device simultaneously, reduce registration block cost.

For achieving the above object, the present invention adopts following technical scheme:

A spatial alternation registration block, it comprises visual indicia, cover plate, N shape mark, base.Visual indicia is pasted or is drawn on the cover board, and cover plate is arranged on base, is provided with N shape mark in base; N shape mark makes or uses the hollow tubular of having filled imaging pulvis or liquor to process by the material that is beneficial to the imaging of volume data collecting device.

Described visual indicia is similar to the tessellated black pattern piece of black and white for what at least have three public vertex, and these public vertex conllinear not.

In described N shape mark, be full of liquor or the pulvis for the imaging of volume data imaging device.

Described cover plate one end is provided with recess, and described base is provided with tang, and recess and tang cooperatively interact.

Adopt a vision locator method for registration block for spatial alternation,

(1) registration block is fixed on operand, by perspective imaging equipment, is obtained the volume data of operand and registration block; Utilize two-layer faultage image in volume data, the center of N shape mark in registration block is positioned to the volume data volume coordinate using this centre coordinate as registration block;

(2) utilize stereoscopic vision positioning system that visual indicia is automatically identified, located, calculate the coordinate of N shape mark center in registration block, using it as registration block the coordinate in visual space;

(3) utilize affine method or SVD method, calculate the spatial alternation battle array of volume data space and visual space, the registration of perfect aspect data space and visual space.

In described step 1), the volume data space-location method of registration block is:

Utilize perspective imaging equipment to obtain the faultage image of registration block, the N shape mark that comprises the pipeline formation that imaging pulvis or liquor are housed in registration block, N shape is marked at bright point-like imaging in image, these imaging points can be with method detection and location such as Edge extraction.Note O is volume data space initial point, and the summit, the lower left corner of N shape mark is designated as n ₁, three summits of along clockwise direction other are designated as respectively n ₂, n ₃, n ₄.Using the center of N shape mark as the position of registration features point, and in volume data space, note should

Position coordinates is m _i(x, y, z), based on space vector relation, its coordinate can be by calculate.

At faultage image I ₁in, can detect outward flange and cornerwise imaging point thereof of the N shape mark obtaining, be designated as respectively a ₁, b ₁, c ₁; At faultage image I ₂the corresponding imaging point that middle detection obtains is designated as respectively a ₂, b ₂, c ₂.

Due on N-type mark, triangle a ₁n ₂b ₁similar in appearance to triangle c ₁n ₄b ₁, i.e. Δ a ₁n ₂b ₁∝ Δ c ₁n ₄b ₁, its corresponding sides grow up to

Ratio, $\left|\right|\frac{b_1{n}_2}{b_1{n}_4}\left|\right|=\left|\right|\frac{a_1{b}_1}{c_1{b}_1}\left|\right|=k,$ Wherein k is constant.

Known N shape mark diagonal line design length is l, has

l＝‖n ₂n ₄‖＝‖b ₁n ₂‖+‖b ₁n ₄‖＝(1+k)‖b ₁n ₄‖＝(1+k)/k·‖b ₁n ₂‖

Due to b ₁, b ₂be positioned at vector upper, wherein, O is volume data space initial point, by the relation between space vector, known,

$\stackrel{\→}{{\mathrm{on}}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·k/{(1+k)}^{\·l}$

$\stackrel{\→}{{\mathrm{on}}_4}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_4}=\stackrel{\→}{{\mathrm{ob}}_1}-\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·1/{(1+k)}^{\·l}$

Therefore,, in volume data image, by image, process and obtain b ₁, b ₂coordinate after, can calculate registration features point coordinate m corresponding to registration block _i.

Described step 2) in, the visual space localization method of registration block is:

Visual indicia consists of 3 or more black pattern piece common point, utilizes the visual space location of this visual indicia to registration block; It is taken pictures to visual indicia with stereoscopic camera, utilizes image processing algorithm, extracts black pattern piece common point and calculates the three-dimensional coordinate of each common point; According to the difference of the geometry distribution characteristics of black pattern piece common point, can different registration block automatically be identified and be located;

Note is any three black pattern piece common point A of conllinear not on visual indicia, B, and the visual space coordinate of C is respectively

A _c(A _x, A _y, A _z), B _c(B _x, B _y, B _z), C _c(C _x, C _y, C _z), according to right-hand rule, there is 1 D, the unit of making to directly in plane ABC; The visual coordinate that note D is ordered is D _c(D _x, D _y, D _z), this coordinate can be by with try to achieve.Take A as initial point, set up the reference frame coordinate system of visual indicia, note A, B, C, D is at this reference frame

Under coordinate be respectively A _r(0,0,0), B _r(B _rx, B _ry, B _rz), C _r(C _rx, C _ry, C _rz), D _r(D _rx, D _ry, D _rz), utilize affined transformation, try to achieve the transformation matrix that reference coordinate is tied to visual coordinate system and be ^ct _r,

${}^C{T}_R=\left[\begin{array}{cccc}{A}_x& B_x& C_x& D_x\\ A_y& B_y& C_y& D_y\\ A_z& B_z& C_z& D_z\\ 1& 1& 1& 1\end{array}\right]\·{\left[\begin{array}{cccc}0& B_{\mathrm{rx}}& C_{\mathrm{rx}}& D_{\mathrm{rx}}\\ 0& B_{\mathrm{ry}}& C_{\mathrm{ry}}& D_{\mathrm{ry}}\\ 0& B_{\mathrm{rz}}& C_{\mathrm{rz}}& D_{\mathrm{rz}}\\ 1& 1& 1& 1\end{array}\right]}^{-1}$

From design and installation parameter, the coordinate m of the center of N shape mark under visual indicia reference frame coordinate system _r(x _r, y _r, z _r).The registration features point coordinate of registration block in visual space, the i.e. coordinate of the center of N shape mark under visual coordinate system

M _c(x _c, y _c, z _c), can be by $\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]={}^C{T}_R\left[\begin{array}{c}{x}_r\\ y_r\\ z_r\\ 1\end{array}\right]$ Calculate.

In described step 3), the method for registering of volume data space and visual space is:

Use four registration block, in volume data space and visual space calculate registration block according to the method for the invention respectively, the coordinate of N shape mark center, is the coordinate of registration features point, and is designated as m _i1, m _i2, m _i3, m _i4and m _c1, m _c2, m _c3, m _c4, can arrive in the hope of volume data space the transformation matrix of visual space ^ct _i,

^ct _i=[m _c1m _c2m _c3m _c4] [m _i1m _i2m _i3m _i4] ^-1; When using more registration block, can adopt the optimum solution of SVD method solution room transformation matrix.

The present invention is fixed on registration block on processed object, utilizes the volume data image of fluoroscopic apparatus generating run object; By image, process and calculate, complete the location of registration features point in volume data space; Utilize stereoscopic camera to complete the location of registration features point in visual space; The elements of a fix according to registration features point in different spaces, realize volume data space to the registration of visual space.

Registration block is comprised of up/down cover plate, visual indicia, N shape mark and frame installation pad, at registration block outside surface, and the visual indicia that stickup or printing are comprised of the tessellated black pattern piece of similar black and white.In N shape mark, be full of liquor or the pulvis that is beneficial to the imaging of volume data imaging device, can obtain blur-free imaging by imaging devices such as X-ray, CT, nuclear magnetic resonance.The visual indicia being comprised of black pattern piece can be identified location automatically by vision positioning system.

Registration block is fixedly connected on operand, by volume data imaging device, carries out imaging, obtains volume data image.Utilize the imaging of N shape mark in 2 width faultage images, can complete the location of registration block in volume data space.Visual indicia is identified location automatically by stereoscopic vision positioning system.After respectively registration block being positioned in volume data space and visual space, obtain the coordinate of registration features point, volume data space is carried out corresponding with gained unique point coordinate in visual space, utilize affine method or SVD method, calculate the spatial alternation battle array of volume data space and visual space, the registration of perfect aspect data space and visual space.The method comprises the following steps:

(1) by perspective imaging equipment, carry out imaging processing, obtain image volumetric data, utilize the imaging of N shape mark in 2 width faultage images, can in volume data space, complete location to registration block;

(2) the automatic recognition visible sensation mark of stereoscopic vision positioning system registration block is positioned;

(3) volume data space and the coordinate of gained registration features point in visual space are carried out corresponding, utilize affine method or SVD method, calculate the spatial alternation battle array of volume data space and visual space, the registration of perfect aspect data space and visual space.

The invention has the beneficial effects as follows: registration block process and assemble that N shape mark forms is simple, compact conformation, as long as N shape mark can exist the two width imagings that meet requirement of the present invention in volume data, can position it, is beneficial to the miniaturization that realizes registration block; Simple to the positioning action of N shape mark in volume data, support rapid registering; By stereoscopic vision, can automatically identify, locate different registration block, improve registration automaticity, avoid personnel's operate miss, improve registration accuracy.

Accompanying drawing explanation

Fig. 1: process flow diagram of the present invention;

Fig. 2: registration block structural representation;

Fig. 3: N shape is marked at the location in volume data space;

Fig. 4: the visual indicia example that the tessellated black pattern piece of black and white forms that is similar to that is attached to registration block outside surface.

Wherein, 1. cover plate, 2. visual indicia, 3. base, 4.N shape mark, 5. supporting plate.

Embodiment

Below in conjunction with accompanying drawing, the present invention will be further described with enforcement.

In Fig. 2, cover plate 1 is arranged on base 3, is provided with visual indicia 2 on cover plate 1, is provided with N shape mark 4 in base 3; Base 3 is arranged on supporting plate 5, at the interior filling imaging substance of N shape mark 4.

Described visual indicia 2 is density bullet.

In described N shape mark 4, be full of liquor or the pulvis for the imaging of volume data imaging device.

In Fig. 1, Fig. 3, Fig. 4, method of the present invention is:

(1) by perspective imaging equipment, registration block is carried out to imaging processing, obtain image volumetric data.Utilize the imaging of N shape mark in 2 width faultage images, can in volume data space, position and the coordinate of point in volume data space using this centre coordinate as registration features the center of N shape mark;

(2) utilize stereoscopic vision positioning system that visual indicia is automatically identified, located, and calculate the coordinate of N shape mark center, using it as registration features point the coordinate in visual space;

(3) utilize affine method or SVD method, calculate the spatial alternation battle array of volume data space and visual space, the registration of perfect aspect data space and visual space.

(1) the volume data space orientation of registration block

After the device scans such as CT, MR, can obtain the faultage image of N shape mark.If O is volume data space initial point; N shape mark and faultage image I ₁intersection point be a ₁, b ₁, c ₁; With faultage image I ₂intersection point be a ₂, b ₂, c ₂; Note summit, the N shape mark lower left corner is n ₁, its summit is designated as respectively n along clockwise direction ₂, n ₃, n ₄,

By

Triangle a ₁n ₂b ₁similar in appearance to triangle c ₁n ₄b ₁,

Have $\left|\right|\frac{b_1{n}_2}{b_1{n}_4}\left|\right|=\left|\right|\frac{a_1{b}_1}{c_1{b}_1}\left|\right|=k$ (corresponding sides grow up to ratio, and wherein k is constant)

Known N shape mark diagonal line design processing length is l, and b ₁be positioned at straight line straight line n ₂n ₄upper, according to geometric relationship, obtain l=‖ n ₂n ₄‖=‖ b ₁n ₂‖+‖ b ₁n ₄the ‖ b of ‖=(1+k) ₁n ₄‖=(1+k)/k ‖ b ₁n ₂‖

Due to b ₁, b ₂be positioned at vector upper, wherein, O is volume data space initial point, by the relation between space vector, known,

$\stackrel{\→}{{\mathrm{on}}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·k/{(1+k)}^{\·l}$

$\stackrel{\→}{{\mathrm{on}}_4}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_4}=\stackrel{\→}{{\mathrm{ob}}_1}-\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·1/{(1+k)}^{\·l}$

In volume data image, by image, process and obtain b ₁, b ₂coordinate after, the coordinate of note registration features point in volume data space is m _i(x, y, z), based on space vector relation, can be by

$\stackrel{\→}{{\mathrm{om}}_I}=\stackrel{\→}{{\mathrm{on}}_2}+(\stackrel{\→}{{\mathrm{on}}_4}-\stackrel{\→}{{\mathrm{on}}_2})/2=\stackrel{\→}{{\mathrm{ob}}_1}+\frac{l}{2}\·\frac{k-1}{1+k}\·\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}$

Calculate the coordinate m of registration features point in volume data space _i(x, y, z).

(2) visual space of registration block location

Visual indicia consists of 3 or the black pattern piece common point that is more similar to black and white gridiron pattern intersection point, utilizes this visual indicia can realize the visual space location to registration block.With stereoscopic camera, visual indicia is taken pictures, utilize image processing algorithm, extract black pattern piece common point and calculate the three-dimensional coordinate of each common point.According to the geometry distribution characteristics of black pattern piece common point, as dot spacing from, the recognition visible sensation marks such as angle, automatically identify and locate different registration block.

Note is any three black pattern piece common point A of conllinear not on visual indicia, B, and the visual space coordinate of C is respectively

A _c(A _x, A _y, A _z), B _c(B _x, B _y, B _z), C _c(C _x, C _y, C _z), according to right-hand rule, there is 1 D, make vector of unit length perpendicular to plane ABC.The visual coordinate that note D is ordered is D _c(D _x, D _y, D _z), the visual coordinate that D is ordered can be by try to achieve.Take A as initial point, set up the reference frame coordinate system of visual indicia, note

A, B, C, the coordinate of D under this reference frame is respectively A _r(0,0,0), B _r(B _rx, B _ry, B _rz), C _r(C _rx, C _ry, C _rz), D _r(D _rx, D _ry, D _rz), utilizing affined transformation, the transformation matrix that can to visual coordinate be in the hope of reference frame is ^ct _r,

${}^C{T}_R=\left[\begin{array}{cccc}{A}_x& B_x& C_x& D_x\\ A_y& B_y& C_y& D_y\\ A_z& B_z& C_z& D_z\\ 1& 1& 1& 1\end{array}\right]\·{\left[\begin{array}{cccc}0& B_{\mathrm{rx}}& C_{\mathrm{rx}}& D_{\mathrm{rx}}\\ 0& B_{\mathrm{ry}}& C_{\mathrm{ry}}& D_{\mathrm{ry}}\\ 0& B_{\mathrm{rz}}& C_{\mathrm{rz}}& D_{\mathrm{rz}}\\ 1& 1& 1& 1\end{array}\right]}^{-1}$

From design and installation parameter, the coordinate of the center of N shape mark under visual indicia reference frame coordinate system is m _r(x _r, y _r, z _r).The registration features point coordinate of registration block in visual space, the coordinate of the center of N shape mark under visual coordinate system is m _c(x _c, y _c, z _c), by $\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]={}^C{T}_R\left[\begin{array}{c}{x}_r\\ y_r\\ z_r\\ 1\end{array}\right]$ Calculate.

(3) registration of volume data space and visual space

Use four registration block, in volume data space and visual space calculate registration block according to the method for the invention respectively, the coordinate of N shape mark center, as the position of registration features point, and is designated as m _i1, m _i2, m _i3, m _i4and m _c1, m _c2, m _c3, m _c4, can arrive in the hope of volume data space the transformation matrix of visual space ^ct _i,

^CT _I＝[m _C1?m _C2?m _C3?m _C4][m _I1?m _I2?m _I3?m _I4] ^-1。

When using more registration block, can utilize SVD method to obtain the optimum solution of spatial alternation battle array.

Sign by above-mentioned mathematical way can comparatively accurately realize the location of registration block in volume data space and visual space, and perfect aspect data space is to the registration of visual space.

(4) experiment and emulation

Utilize method in the present invention to try to achieve registration features point in N shape mark and in the sterically defined precision of volume data, be mainly subject to the impact of image quality, the positioning error to its imaging in faultage image is less than 1mm.

The N shape mark that the spherical labels thing that use diameter is 10mm and 2mm caliber manufactured size are 25mm*15mm carries out many experiments and emulation experiment comparison.In image space: the error of manually locating spherical label is 2.2mm; Spherical labels thing localization method positioning error is 0.82mm, and the inventive method positioning error is less than 0.5mm; In visual space: spherical labels thing is difficult for realizing location automatically, and the positioning error that adopts semi-automatic localization method is 1.2mm, and adopting patent 201010105470.6 methods is 0.3mm to the positioning error of visual indicia described in this patent.

Claims (4)

1. the vision locator method of registration block for spatial alternation, described registration block, it comprises cover plate, cover plate is arranged on base, is on the cover board provided with the visual indicia of pasting or drawing, and is provided with N shape tag block in base; Floor installation, on supporting plate, is hollow tubular at N shape tag block, fills imaging substance in it;

Described visual indicia is similar to the tessellated black pattern piece of black and white for what at least have three public vertex, and these public vertex conllinear not;

Described imaging substance is liquor or the pulvis for the imaging of volume data imaging device;

Described cover plate one end is provided with recess, and described base is provided with tang, and recess and tang cooperatively interact;

It is characterized in that,

(1) registration block is fixed on operand, by perspective imaging equipment, is obtained the volume data of operand and registration block; Utilize two-layer faultage image in volume data, the center of N shape mark in registration block is positioned to the volume data volume coordinate using this centre coordinate as registration block;

(2) utilize stereoscopic vision positioning system that visual indicia is automatically identified, located, calculate the coordinate of N shape mark center in registration block, using it as registration block the coordinate in visual space;

(3) utilize affine method or SVD method, calculate the spatial alternation battle array of volume data space and visual space, the registration of perfect aspect data space and visual space.

2. the method for claim 1, is characterized in that, in described step (1), the volume data space-location method of registration block is:

Utilize perspective imaging equipment to obtain the faultage image of registration block, comprise the N shape mark that the pipeline of imaging pulvis or liquor forms is housed in registration block, N shape is marked at bright point-like imaging, the image edge extraction method detection and location of these imaging points in image; Note O is volume data space initial point, and the summit, the lower left corner of N shape mark is designated as n ₁, three summits of along clockwise direction other are designated as respectively n ₂, n ₃, n ₄; Using the center of N shape mark as the position of registration features point, in volume data space, remember that this position coordinates is m _i(x, y, z), based on space vector relation, its coordinate by calculate;

At faultage image I ₁in, outward flange and cornerwise imaging point thereof of the N shape mark that detection obtains, be designated as respectively a ₁, b ₁, c ₁; At faultage image I ₂the corresponding imaging point that middle detection obtains is designated as respectively a ₂, b ₂, c ₂;

Due on N-type mark, triangle a ₁n ₂b ₁similar in appearance to triangle c ₁n ₄b ₁, i.e. Δ a ₁n ₂b ₁∝ Δ c ₁n ₄b ₁, its corresponding sides grow up to ratio, wherein k is constant;

Known N shape mark diagonal line design length is l, has

l＝||n ₂n ₄||＝||b ₁n ₂||+||b ₁n ₄||＝(1+k)||b ₁n ₄||＝(1+k)/k·||b ₁n ₂||

Due to b ₁, b ₂be positioned at vector upper, wherein, O is volume data space initial point, by the relation between space vector, known,

$\stackrel{\→}{{\mathrm{on}}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_2}=\stackrel{\→}{{\mathrm{ob}}_1}+\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·k/(1+k)\·l$

$\stackrel{\→}{{\mathrm{on}}_4}=\stackrel{\→}{{\mathrm{ob}}_1}+\stackrel{\→}{b_1{n}_4}=\stackrel{\→}{{\mathrm{ob}}_1}+\frac{\stackrel{\→}{b_1{b}_2}}{\left|\right|b_1{b}_2\left|\right|}\·1/(1+k)\·l$

Therefore,, in volume data image, by image, process and obtain b ₁, b ₂coordinate after, calculate registration features point coordinate m corresponding to registration block _i.

3. the method for claim 1, is characterized in that, the visual space localization method of registration block is in described step (2): visual indicia consists of 3 or more black pattern piece common point, utilizes the visual space location of this visual indicia to registration block; It is taken pictures to visual indicia with stereoscopic camera, utilizes image processing algorithm, extracts black pattern piece common point and calculates the three-dimensional coordinate of each common point; According to the difference of the geometry distribution characteristics of black pattern piece common point, different registration block are automatically identified and located;

Note is any three black pattern piece common point A of conllinear not on visual indicia, B, and the visual space coordinate of C is respectively A _c(A _x, A _y, A _z), B _c(B _x, B _y, B _z), C _c(C _x, C _y, C _z), according to right-hand rule, there is 1 D, make vector of unit length perpendicular to plane ABC; The visual coordinate that note D is ordered is D _c(D _x, D _y, D _z), this coordinate by with try to achieve; Take A as initial point, set up the reference frame coordinate system of visual indicia, note A, B, C, the coordinate of D under this reference frame is respectively A _r(0,0,0), B _r(B _rx, B _ry, B _rz), C _r(C _rx, C _ry, C _rz), D _r(D _rx, D _ry, D _rz), utilize affined transformation, try to achieve the conversion square that reference coordinate is tied to visual coordinate system and be ^ct _r,

$T_R^C=\left[\begin{array}{cccc}{A}_x& B_x& C_x& D_x\\ A_y& B_y& C_y& D_y\\ A_z& B_z& C_z& D_z\\ 1& 1& 1& 1\end{array}\right]\·{\left[\begin{array}{cccc}0& B_{\mathrm{rx}}& C_{\mathrm{rx}}& D_{\mathrm{rx}}\\ 0& B_{\mathrm{ry}}& C_{\mathrm{ry}}& D_{\mathrm{ry}}\\ 0& B_{\mathrm{rz}}& C_{\mathrm{rz}}& D_{\mathrm{rz}}\\ 1& 1& 1& 1\end{array}\right]}^{-1}$

From design and installation parameter, the coordinate of the mid point of N shape tag block under visual indicia reference frame coordinate system is m _r(x _r, y _r, z _r), the registration features point coordinate of registration block in visual space, the coordinate of the center of N shape mark under visual coordinate system by $\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\\ 1\end{array}\right]=T_R^C\left[\begin{array}{c}{x}_r\\ y_r\\ z_r\\ 1\end{array}\right]$ Calculate.

4. the method for claim 1, it is characterized in that, in described step (3), the method for registering of volume data image space and visual space is: use four registration block, the coordinate of N shape mark center in volume data space and visual space calculate registration block, be the coordinate of registration features point, and be designated as m _i1, m _i2, m _i3, m _i4and m _c1, m _c2, m _c3, m _c4, try to achieve volume data space to the transformation matrix of visual space ^ct _i,

? ^ct _i=[m _c1m _c2m _c3m _c4] [m _i1m _i2m _i3m _i4] ^-1; When using more registration block, utilize SVD method to obtain the optimum solution of transformation matrix.