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3 JOURNAL OF SHANGHAI SECOND POLYTECHNIC UNIVERSITY Vol. 31 No. 3 Sep : (2014) VTK (, ) : CT VTK(Visualization Toolkit, ) ; VC++ VTK ; STL,, : VTK; ; ; ; : TP391.4 : A 0,, CT MRI( ),,, [1] VC++,, OpenGL (Open Graphics Library, ),, Kitware 1998 VTK (Visualization Toolkit, ), OpenGL [2], CT,, VTK, 1 CT,,, :,,, T, [3] : f 0 255, i n i, N, ( ) P i = n i (i = 0, 1,, 255) N T, A B, A: P 0 P, P 1 P,, P T P, B: P T +1 1 P, P T +2 1 P,, P 255 T 1 P, P = P i, A B : i=0 : : (1977 ),,,,, daihong@sspu.edu.cn : ( ) (No. XXKZD1302)

4 S A = S B = T i=0 255 i=1+t P i P lg P i P P i 1 P lg P i 1 P (1) (2) : S(T ) = S A + S B, T k S(T ) T, : T k = arg max S(T ) (3) 2 VTK 2.1, :, ( ) (Marching Cubes),, [4], : ; ;,, ; ;, ;, : (1) CT ( 145 ), 2,, ,, 1 ( ), 143 f(x, y, z), f f(x, y, z) = T k (4), T k, (2) 8,,,, Q = (Q 1 + Q 2 )/2 (5) : Q ; Q 1 Q 2, 2.2 VTK VTK (Pipeline),, [5] Marching Cubes, VC++6.0 VTK 1 vtkdicomimagereader vtkimageshrink3d vtkmarchingcubes vtkpolydatanormals vtksmoothpolydatafilter vtkstlwriter vtkactor vtkrenderer vtkrenderwindow vtkrenderwindowinteractor 1 Marching Cube Fig. 1 The surface rendering pipeline model of the foot bones based on Marching Cube Algorithm, VTK ( ) : (1) vtkdicomimagereader [6], D zubu dicom ( ) CT, 145 void main() { vtkdicomimagereader *v16 = vtkdicomimagereader::new(); v16->setdatabyteordertolittleendian(); // v16->setdirectoryname( D://zubu );// v16->setdataspacing (1, 1, 1);//

5 3 : VTK 213 (2) vtkimageshrink3d,, vtkimageshrink3d *v17= vtkimageshrink3d:: New(); v17->setinput((vtkdataobject*)v16->getoutput()); v17->setshrinkfactors(2, 2, 1);// 2 : 2 : 1 (3) MarchingCubes, vtkmarchingcubes *skinextractor = vtkmarchingcubes::new(); skinextractor->setinputconnection(v17-> skinextractor->setvalue(0, 123.5);// T k =123.5 (4) vtkpolydatanormals, vtkpolydatanormals *skinnormals = vtkpolydatanormals::new(); skinnormals->setinputconnection(skinextractor -> skinnormals->setfeatureangle(60.0); (5) vtksmoothpolydatafilter [7] ; vtkstlwriter STL vtksmoothpolydatafilter *smoother= vtksmoothpolydatafilter::new(); smoother->setinputconnection(skinextractor-> smoother->setnumberofiterations(50); vtkstlwriter *writer=vtkstlwriter::new(); writer->setinputconnection(smoother-> writer->setfilename( zubu.stl ); writer-> Write(); // STL zubu.stl (6) vtkpolydatamapper ; vtkactor,, vtkpolydatamapper *skinmapper = vtkpolydatamapper::new(); skinmapper->setinputconnection (smoother-> skinmapper->scalarvisibilityoff(); vtkactor *skin = vtkactor::new(); skin->setmapper(skinmapper); skin-> GetProperty()->SetColor(0, 1, 0); (7) vtkrenderer,, vtkrenderwindow, vtkrenderwindowinteractor vtkrenderer *arenderer= vtkrenderer::new(); arenderer->addactor(skin); arenderer-> SetBackground(1, 1, 1);// New(); vtkrenderwindow *renwin= vtkrenderwindow:: renwin->addrenderer(arenderer); renwin-> SetSize(640, 480);// 640*480 vtkrenderwindowinteractor *iren = vtkrenderwindowinteractor::new(); iren->setrenderwindow(renwin);} 3 CT, , 145, dicom Matlab,, 43 ( 2(a)), : S(T ); T = 1, 2,, 255, S(T ), S(T ) T k T k = 123.5, 2(b), (a) (b) 2 Fig. 2 The segmented image of foot bones based on Maximum Entropy Threshold Algorithm

6 T k = 123.5, VC++ VTK, 3 Marching Cubes ;, :, , s 4.84 s, ;,, SolidWorks UG STL, 4 3 VTK Fig. 3 Three dimensional visualization of foot bones base on VTK VTK : ;, VTK,, CT,, : [1],. Matlab [J] , 26(4): [2],,. [M]. :, [3],,. [J]., 2009, 26(3): [4],,. [M]. :, [5],. MC VTK [J] , 28(13): [6] VITAMIN. vtkdicomreader [EB/OL]. ( ) [ ] com/blog/static/ /. [7],. VTK [J]., 2009(1): Three Dimensional Visualization of Foot Bones Based on Visualization Toolkit DAI Hong (School of Electronic and Electric Engineering, Shanghai Second Polytechnic University, Shanghai , P. R. China) Abstract: The three dimensional reconstruction of foot bones based on CT image sequences using VTK (Visualization Toolkit) is proposed. (1) The foot bones images are segmented by Maximum Entropy Threshold Algorithm and the threshold is used as an isosurface extraction value of bones. (2) The surface rendering of foot bones based on Marching Cubes Algorithm is realized by VTK programmed with VC++, and the three dimensional surfaces of bones are optimized and stored in STL, and a general 3D model file format. The result of experiment shows that this method obtained desired effect of visualization, and it can play an important role in the diagnosis and treatment for foot diseases and the operation simulation of foot. Keywords: VTK; foot bones; three dimensional visualization; surface rendering; Maximum Entropy Threshold Algorithm

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