simple opencv 2411 flann point match example practice

flann function in opencv is good for point match, which find nearest point from A points to B points, it is useful for tracking, iterative closest point (ICP) algorithm...

I copy the code from this website:

https://github.com/royshil/morethantechnical/blob/master/ICP/MyICP.cpp

and make it simple for me to understand.

code:

#include "cv.h"
#include "highgui.h"
#include <iostream>
#include <vector>
#include <limits>
using namespace cv;
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
 Mat X(5,2,CV_32SC1); 
 X.at<Point>(0,0)=Point(1,1);
 X.at<Point>(1,0)=Point(5,5);
 X.at<Point>(2,0)=Point(10,10);
 X.at<Point>(3,0)=Point(15,15);
 X.at<Point>(4,0)=Point(20,20);
 Mat destinations(10,2,X.type());
 destinations.at<Point>(0,0)=Point(30,30);
 destinations.at<Point>(1,0)=Point(6,6);
 destinations.at<Point>(2,0)=Point(11,11);
 destinations.at<Point>(3,0)=Point(17,17);
 destinations.at<Point>(4,0)=Point(23,23);
 destinations.at<Point>(5,0)=Point(25,25);
 destinations.at<Point>(6,0)=Point(2,2);
 destinations.at<Point>(7,0)=Point(16,16);
 destinations.at<Point>(8,0)=Point(40,40);
 destinations.at<Point>(9,0)=Point(21,21);
 cv::Mat m_indices(X.rows, 1, CV_32S);
 cv::Mat m_dists(X.rows, 1, CV_32F);
 Mat dest_32f; destinations.convertTo(dest_32f,CV_32FC2);  //convert
 Mat X_32f; X.convertTo(X_32f,CV_32FC2);
 cv::flann::Index flann_index(dest_32f, cv::flann::KDTreeIndexParams(2));  // using 2 randomized kdtrees, 1 is ok ,too
 flann_index.knnSearch(X_32f, m_indices, m_dists, 1, cv::flann::SearchParams(64) );
 cout<<"indice:"<<m_indices<<endl;
 cout<<"dist  :"<<m_dists<<endl;
 for(int i=0;i<5;i++)
 {
  cout<<i<<" in X match to "<<m_indices.at<int>(i)<<" in destinations"<<endl;
  cout<<"distance is : "<<m_dists.at<float>(i)<<endl;
 }
 system("pause");
}

the output should be:

indice:[6;
  1;
  2;
  7;
  9]
dist  :[2;
  2;
  2;
  2;
  2]
0 in X match to 6 in destinations
distance is : 2
1 in X match to 1 in destinations
distance is : 2
2 in X match to 2 in destinations
distance is : 2
3 in X match to 7 in destinations
distance is : 2
4 in X match to 9 in destinations
distance is : 2
Press any key to continue . . .

simple opencv drawing opengl example

draw 2 sphere and a rotating cube in opencv by opengl using opencv setopengldrawcallback

the opencv should be cmaked and check the "WITH_OPENGL"





float gggg=55;
float gginin=3.14/6;
void on_opengl(void* param)
{
 //draw a cube
 glLoadIdentity();
 gluLookAt(20*cos(gginin), 0, 20*sin(gginin), 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
 glTranslated(0.0, 0.0, -1.0);
 glDrawArrays(GL_POINTS, 0, 1);
 glRotatef( gggg, 1, 0, 0 );
 //glRotatef( gggg, 0, 1, 0 );
 //glRotatef( gggg, 0, 0, 1 );
 static const int coords[6][4][3] = {
  { { +1, -1, -1 }, { -1, -1, -1 }, { -1, +1, -1 }, { +1, +1, -1 } },
  { { +1, +1, -1 }, { -1, +1, -1 }, { -1, +1, +1 }, { +1, +1, +1 } },
  { { +1, -1, +1 }, { +1, -1, -1 }, { +1, +1, -1 }, { +1, +1, +1 } },
  { { -1, -1, -1 }, { -1, -1, +1 }, { -1, +1, +1 }, { -1, +1, -1 } },
  { { +1, -1, +1 }, { -1, -1, +1 }, { -1, -1, -1 }, { +1, -1, -1 } },
  { { -1, -1, +1 }, { +1, -1, +1 }, { +1, +1, +1 }, { -1, +1, +1 } }
 };
 for (int i = 0; i < 6; ++i) {
  glColor3ub( i*20, 100+i*10, i*42 );
  glBegin(GL_QUADS);
  for (int j = 0; j < 4; ++j) {
   glVertex3d(0.2 * coords[i][j][0], 0.2 * coords[i][j][1], 0.2 * coords[i][j][2]);
  }
  glEnd();
 }
 //draw a sphere
 glLoadIdentity();
 gluLookAt(20*cos(gginin), 0, 20*sin(gginin), 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
 glTranslatef(1.0f,2.0f,1.0f);
 glColor3ub( 255,0,0);
 glBegin(GL_TRIANGLES);
 GLUquadricObj *quadric;
 quadric = gluNewQuadric();
 gluQuadricDrawStyle(quadric, GLU_FILL );
 gluSphere( quadric , .1 , 36 , 18 );
 glEnd();
 //draw another sphere
 glLoadIdentity();
 gluLookAt(20*cos(gginin), 0, 20*sin(gginin), 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
 glTranslatef(4.1f, 2.45f, 10.0f);
 glBegin(GL_TRIANGLES);
 GLUquadricObj *quadric2;
 quadric2 = gluNewQuadric();
 gluQuadricDrawStyle(quadric2, GLU_FILL );
 gluSphere( quadric , .6 , 36 , 18 );
 glEnd();
 glLoadIdentity();
}
int _tmain(int argc, _TCHAR* argv[])
{
 string openGLWindowName = "OpenGL Test";
 namedWindow(openGLWindowName, WINDOW_OPENGL);
 resizeWindow(openGLWindowName, 640, 480);
 glMatrixMode( GL_PROJECTION );
 glLoadIdentity();
 gluPerspective(90.0, 640/480, 1, 1000000.0);
 glMatrixMode(GL_MODELVIEW);
 setOpenGlContext(openGLWindowName);
 setOpenGlDrawCallback(openGLWindowName, on_opengl, NULL);
 while(true)
 {
  updateWindow(openGLWindowName);// when needed
  gggg++;
  gginin+=3.14/36;
  cvWaitKey(30);
  cout<<"ggininder"<<endl;
 }
return 0;
}