CN103279984B - A kind of sight glass viewing angle tracking method of graphic based transformation matrix - Google Patents

Abstract

The present invention is a kind of sight glass viewing angle tracking method of graph transformation matrix, can show the sight glass visual angle of scalpel, belong to the field of Computer Graphics in areas of information technology in virtual operation training system.Propose a kind of algorithm of graphic based transformation matrix, by changing the spatial coordinate location of several calibration point, constructing one and can follow the tool motion in virtual operation training system and the visual angle of moving, thus reaching the effect at sight glass visual angle.This method uses absolute type variable quantity, decrease the cumulative errors of image data in tool motion process, by calibration during initialization, eliminate steady-state error, make simultaneously visual angle can with portion's mechanical linkage, reduce the associative operation in true operation completely, and operand is less, antijamming capability is good.

Description

A kind of sight glass viewing angle tracking method of graphic based transformation matrix

Technical field

The present invention relates to the field of Computer Graphics under areas of information technology.

Background technology

Neuro-surgery operation is the important means for the treatment of neuro-surgery disease at present, but because brain organ structure complexity, some diseased region are near important histoorgan, makes neuro-surgery operation complicated and challenging.Therefore, accurately show all brain structures information such as brain functional areas, nerve fibre trend, and the operative training system of high-fidelity is provided, raising neuro-surgery operation level is had great importance.

Current operative training systematic research both domestic and external makes some progress, as American I ntuitiveSurgical company successfully develops DaVinci surgical robot systems, and has dropped into business use; The software systems that the people such as the PeterC.Everett of Harvard Medical School SurgicalPlanningLaboratory utilize VTK to develop can be carried out mutual cutting and can be demonstrated the change of topological structure on triangular facet model.The MeVisTo-Jaw system of people's exploitations such as the PatrickNeumann of Germany FreeUniversityofBerlin can simulate craniofacial surgery in three-dimensional scenic, this system is the cutting that the method utilizing volume data to operate carrys out analog bone tissue, and utilize the device such as anaglyph spectacles and force feedback to increase the authenticity of surgical simulation, but also there is following problem in these operative training systems:

First, surgical navigational and training system operation observation point are static observation point.Current operative training system is as the VectorVision system of Germany, and only have the static observation point that 5 fixing, it realizes the tracking of knife head for surgical by all brain structures of transparence virtual patient, lacks the authenticity of sham operated.

Secondly, virtual sight glass visual angle is lacked.In real neurosurgery Minimally Invasive Surgery, doctor normally obtains the data message of scalpel periphery by the sight glass being arranged on knife head for surgical, and this observation station moves along with the movement of scalpel mirror sheath, can ensure the real-time monitoring to knife head for surgical.The observation visual angle of current operative training system is many is specified by user, can not change with the movement of analog scalpel.

Summary of the invention

In order to the training system visual angle overcoming prior art is untrue, cause the shortcoming that operative training and actual operation disconnect, we propose a kind of sight glass viewing angle tracking method of graphic based transformation matrix, simulate sight glass visual angle with dynamic concept measuring point, make operative training system more close to true operation.

The technical solution used in the present invention is:

A sight glass viewing angle tracking method for graphic based transformation matrix, mainly comprises following three steps:

Step 1, obtains the spatial parameter of digital scalpel in Virtual Space:

Described spatial parameter comprises camera position (Position), camera focus (FocusPoint) and upwardly-directed (ViewUp), position on camera position and digital scalpel residing for virtual camera point, the position at camera place in Reality simulation operation; The focal position at camera focus and visual angle, is mainly used to jointly form sight line vector with camera position; It is upwardly-directed the y-axis positive dirction of view plane; By setting up Virtual Space in computing machine, and for setting up coordinate axis in this Virtual Space, digitizing scalpel is imported this Virtual Space, thus using the position of virtual camera point that gets as camera position P (P _x, P _y, P _z), with P point along the position of y-axis positive dirction 5 units being second some F (F _x, F _y, F _z), as camera focus, wherein be sight line vector, a V (V is in the position of P point and mirror sheath axisymmetrical _x, V _y, V _z), it is view plane positive direction vector.

Step 2, according to scalpel model sport, carry out coordinate transform:

We set up the graphics transformation matrix R of three 4x4 _x, R _z, T _ycarry out the change at sight glass visual angle, wherein, R _xcamera point transformation matrix when x-axis rotates, R _zthe transformation matrix of point when z-axis rotates, T _ybe the transformation matrix of point along the direction translation of tool coordinate y-axis, be specially:

$R_x=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& \cos \mathrm{\α}& sin\mathrm{\α}& 0\\ 0& -sin\mathrm{\α}& \cos \mathrm{\α}& 0\\ 0& 0& 0& 1\end{array}\right);$

$R=\left(\begin{array}{cccc}cos\mathrm{\β}& sin\mathrm{\β}& 0& 0\\ -sin\mathrm{\β}& cos\mathrm{\β}& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right);$

$T_y=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\\ 0& T& 0& 1\end{array}\right);$

α represents the angle that cutter rotates through from initial position around x-axis; β represents the angle that cutter rotates through from initial position around z-axis; T represents the translation of cutter relative initial position on tool coordinate y-axis direction;

By obtaining above:

${\stackrel{\→}{P}}^{\′}=\stackrel{\→}{P}*T_y*R_x*R_z;$

${\stackrel{\→}{F}}^{\′}=\stackrel{\→}{F}*T_y*R_x*R_z;$

${\stackrel{\→}{V}}^{\′}=\stackrel{\→}{V}*T_y*R_x*R_z;$

Wherein, $\stackrel{\→}{P}=(P_x,P_y,P_z,1),(P_x,P_y,P_z)$ Represent initial P point coordinate, 1 converts for companion matrix; ${\stackrel{\→}{P}}^{\′}=({P^{\′}}_x,{P^{\′}}_y,{P^{\′}}_z,1),$ $({P^{\′}}_x,{P^{\′}}_y,{P^{\′}}_z)$ Represent post exercise P point coordinate P', 1 converts for companion matrix; $\stackrel{\→}{F}=(F_x,F_y,F_z,1),(F_x,F_y,F_z)$ Represent initial F point coordinate, 1 converts for companion matrix; represent post exercise F point coordinate F', 1 converts for companion matrix; represent initial V point coordinate, 1 converts for companion matrix; represent post exercise V point coordinate V', 1 converts for companion matrix;

Now P' represents the position at visual angle, constitute view plane normal vector, constitute view plane positive dirction;

Step 3, redraws sight glass visual angle:

Camera position is given respectively by P', F', V', camera focus and upwardly-directed, then system can according to current camera point position and a upper moment camera point position calculation go out current visual angle towards, redraw the object that camera point thus observes, complete sight glass visual angle display.

Useful performance of the present invention is:

1. make operative training truer.By applying virtual sight glass visual angle technology in training system, the sight glass visual angle of Reality simulation operation, thus improve doctor institute of undergoing training and obtain the validity of training image information, raising training effect.

2. assist physicians better observes focal area.Virtual sight glass visual angle, with the interlock of digitizing scalpel, is being carried out in operative training process, can come omnibearing observation focal area, make virtual operation process more accurate by operation cutter.

Accompanying drawing explanation

Fig. 1 is the design sketch that the present invention realizes in VTK model

Fig. 2 is analog scalpel model of the present invention

Fig. 3 is sight glass camera point position of the present invention

Embodiment

Below with reference to accompanying drawing, the present invention is described in further details:

With reference to accompanying drawing 1-3,

A sight glass viewing angle tracking method for graphic based transformation matrix, mainly comprises following three steps:

Step 1, obtains the spatial parameter of digital scalpel in Virtual Space:

Described spatial parameter comprises camera position (Position), camera focus (FocusPoint) and upwardly-directed (ViewUp), position on camera position and digital scalpel residing for virtual camera point, the position at camera place in Reality simulation operation; The focal position at camera focus and visual angle, is mainly used to jointly form sight line vector with camera position; It is upwardly-directed the y-axis positive dirction of view plane; By setting up Virtual Space in computing machine, and for setting up coordinate axis in this Virtual Space, digitizing scalpel is imported this Virtual Space, thus using the position of virtual camera point that gets as camera position P (P _x, P _y, P _z), with P point along the position of y-axis positive dirction 5 units being second some F (F _x, F _y, F _z), as camera focus, wherein be sight line vector, a V (V is in the position of P point and mirror sheath axisymmetrical _x, V _y, V _z), it is view plane positive direction vector.

Step 2, according to scalpel model sport, carry out coordinate transform:

We set up the graphics transformation matrix R of three 4x4 _x, R _z, T _ycarry out the change at sight glass visual angle, wherein, R _xcamera point transformation matrix when x-axis rotates, R _zthe transformation matrix of point when z-axis rotates, T _ybe the transformation matrix of point along the direction translation of tool coordinate y-axis, be specially:

$R_x=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& cos\mathrm{\α}& sin\mathrm{\α}& 0\\ 0& -sin\mathrm{\α}& \cos \mathrm{\α}& 0\\ 0& 0& 0& 1\end{array}\right);$

$R_z=\left(\begin{array}{cccc}cos\mathrm{\β}& sin\mathrm{\β}& 0& 0\\ -sin\mathrm{\β}& cos\mathrm{\β}& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right);$

$T_y=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\\ 0& T& 0& 1\end{array}\right);$

α represents the angle that cutter rotates through from initial position around x-axis; β represents the angle that cutter rotates through from initial position around z-axis; T represents the translation of cutter relative initial position on tool coordinate y-axis direction;

By obtaining above:

${\stackrel{\→}{P}}^{\′}=\stackrel{\→}{P}*T_y*R_x*R_z;$

${\stackrel{\→}{F}}^{\′}=\stackrel{\→}{F}*T_y*R_x*R_z;$

${\stackrel{\→}{V}}^{\′}=\stackrel{\→}{V}*T_y*R_x*R_z;$

Wherein, $\stackrel{\→}{P}=(P_x,P_y,P_z,1),(P_x,P_y,P_z)$ Represent initial P point coordinate, 1 converts for companion matrix; ${\stackrel{\→}{P}}^{\′}=({P^{\′}}_x,{P^{\′}}_y,{P^{\′}}_z,1),$ $({P^{\′}}_x,{P^{\′}}_y,{P^{\′}}_z)$ Represent post exercise P point coordinate P', 1 converts for companion matrix; $\stackrel{\→}{F}=(F_x,F_y,F_z,1),(F_x,F_y,F_z)$ Represent initial F point coordinate, 1 converts for companion matrix; represent post exercise F point coordinate F', 1 converts for companion matrix; represent initial V point coordinate, 1 converts for companion matrix; represent post exercise V point coordinate V', 1 converts for companion matrix;

Now P' represents the position at visual angle, constitute view plane normal vector, constitute view plane positive dirction;

Step 3, redraws sight glass visual angle:

Camera position is given respectively by P', F', V', camera focus and upwardly-directed, then system can according to current camera point position and a upper moment camera point position calculation go out current visual angle towards, redraw the object that camera point thus observes, complete sight glass visual angle display.

Claims (1)

1. a sight glass viewing angle tracking method for graphic based transformation matrix, mainly comprises following three steps:

Step 1, obtains digital scalpel spatial parameter in Virtual Space:

Described spatial parameter comprises camera position (Position), camera focus (FocusPoint) and upwardly-directed (ViewUp), position on camera position and digital scalpel residing for virtual camera point, the position at camera place in Reality simulation operation; The focal position at camera focus and visual angle, is mainly used to jointly form sight line vector with camera position; It is upwardly-directed the y-axis positive dirction of view plane; By setting up Virtual Space in computing machine, and for setting up coordinate axis in this Virtual Space, digitizing scalpel is imported this Virtual Space, thus using the virtual camera point position that gets as camera position P (P _x, P _y, P _z), with P point along the position of y-axis positive dirction 5 units being second some F (F _x, F _y, F _z), as camera focus, wherein be sight line vector, a V (V is in the position of P point and mirror sheath axisymmetrical _x, V _y, V _z), it is view plane positive direction vector;

Step 2, according to scalpel model sport, carry out coordinate transform:

Set up three 4 × 4 graphics transformation matrix R _x, R _z, T _ycarry out sight glass visual angle change, wherein, R _xcamera point transformation matrix when x-axis rotates, R _zthe transformation matrix of camera point when z-axis rotates, T _ybe the transformation matrix of camera point along the direction translation of tool coordinate y-axis, be specially:

$R_x=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& \cos \mathrm{\α}& \sin \mathrm{\α}& 0\\ 0& -sin\mathrm{\α}& \cos \mathrm{\α}& 0\\ 0& 0& 0& 1\end{array}\right);$

$R_z=\left(\begin{array}{cccc}cos\mathrm{\β}& sin\mathrm{\β}& 0& 0\\ -sin\mathrm{\β}& cos\mathrm{\β}& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right);$

$T_y=\left(\begin{array}{cccc}1& 0& 0& 0\\ 0& 1& 0& 0\\ 0& 0& 1& 0\\ 0& T& 0& 1\end{array}\right);$

α represents the angle that cutter rotates through from initial position around x-axis; β represents the angle that cutter rotates through from initial position around z-axis; T represents the translation of cutter relative initial position on tool coordinate y-axis direction;

By obtaining above:

${\stackrel{\→}{P}}^{\′}=\stackrel{\→}{P}*T_y*R_x*R_z;$

${\stackrel{\→}{F}}^{\′}=\stackrel{\→}{F}*T_y*R_x*R_z;$

${\stackrel{\→}{V}}^{\′}=\stackrel{\→}{V}*T_y*R_x*R_z;$

Wherein, (P _x, P _y, P _z) represent initial P point coordinate, 1 converts for companion matrix;

(P ' _x, P ' _y, P ' _z) represent post exercise P point coordinate P', 1 converts for companion matrix;

(F _x, F _y, F _z) represent initial F point coordinate, 1 converts for companion matrix;

(F ' _x, F ' _y, F ' _z) represent post exercise F point coordinate F', 1 converts for companion matrix;

(V _x, V _y, V _z) represent initial V point coordinate, 1 converts for companion matrix; (V' _x, V' _y, V' _z) represent post exercise V point coordinate V', 1 converts for companion matrix;

Now P' represents the position at visual angle, constitute view plane normal vector, constitute view plane positive dirction;

Step 3, redraws sight glass visual angle:

Camera position is given respectively by P', F', V', camera focus and upwardly-directed, then system can according to current camera point position and a upper moment camera point position calculation go out current visual angle towards, redraw the object that camera point thus observes, complete sight glass visual angle display.