一、摄像机标定基本步骤
道具的准备：有photoshop、画图之类的公工具自制棋盘，采用A3或A4打印出来，贴到电脑旁的某个位置。
1 新建一个模拟棋盘，标明横向和竖向的角点个数
我绘制的棋盘角点6*7
2 初始化参数，4个内参数，以及畸变参数
3 打开摄像头，获取一帧图像
这里采用Directshow的读取方式，便于向双目的转换。
4 寻找角点并绘出，当找出全部角点（6*7）时，认为该图片有效，存储图片
5每找出一张图片就进行一次标定，更新参数
6对3、4、5循环经过20次之后，显示并存储参数
7对最后一张图片进行校正
做了十几组的实验，存储了每次求出的结果，用#分割，放在data.txt中。
有数据可知，摄像头移动范围和图片模糊程度对精度影响较大，假如摄像头移动范围较窄或者晃动的迅速，会导致结果的偏差偏大。
正常情况下，fx，fy很接近会在490-502附近浮动。
后来尝试，每次的初始化参数使用上一次求出的最终值，即每次程序结束时存储fx，fy，cx，cy的值（input.txt），新一次标定时，首先读取input.txt，进行初始化
但是结果发现并非是收敛的，依然是在一定范围内浮动。
二、配置
将CameraDS.cp和CameraDS.h以及Directshow文件夹copy到工程文件夹下，进行opencv和directshow有关的配置
opencv相关：
1 菜单：Project->Settings，然后将Setting for选为All Configurations，然后选择右边的link标签，在Object/library modules附加上
cxcore.lib cv.lib ml.lib cvaux.lib highgui.lib cvcam.lib
directshow相关：
1. 将CameraDS.h CameraDS.cpp以及目录DirectShow复制到你的项目中
2. 菜单 Project->Settings->Settings for:(All configurations)->C/C++->Category(Preprocessor)->Additional include directories设置为 DirectShow/Include
3. 菜单 Project->Settings->Settings for:(All configurations)->Link->Category(Input)->Additional library directories设置为 DirectShow/Lib
三、运行结果 顺序 fx cx fy cy
500.273193
141.790436
501.506165
136.473099
#
500.273193
141.790436
501.506165
136.473099
#
490.377533
139.145706
491.085449
122.944351
#
501.977661
153.629349
499.712006
128.947861
//以下是源程序：
// 摄像头标定.cpp : Defines the entry point for the console application.
#include "CameraDS.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <cv.h>
#include <highgui.h>
#include <cxcore.h>
#include <cvaux.h>
void InitCorners3D(CvMat *Corners3D, CvSize ChessBoardSize, int Nimages, float SquareSize);//初始化？？
void makeChessBoard();//绘制棋盘
int myFindChessboardCorners( const void* image, CvSize pattern_size,CvPoint2D32f* corners, int* corner_count=NULL,int flags=CV_CALIB_CB_ADAPTIVE_THRESH );
inline int drawCorssMark(IplImage *dst,CvPoint pt)
/***************************************************
Function: main_loop
Description: 绘制一个十字标记
Calls:
Called By:
Input: RGB image, pt
Output:
Return:
Others: 需要检查坐标是否越界 to do list
*************************************************/
{
const int cross_len = 4;
CvPoint pt1,pt2,pt3,pt4;
pt1.x = pt.x;
pt1.y = pt.y - cross_len;
pt2.x = pt.x;
pt2.y = pt.y + cross_len;
pt3.x = pt.x - cross_len;
pt3.y = pt.y;
pt4.x = pt.x + cross_len;
pt4.y = pt.y;
cvLine(dst,pt1,pt2,CV_RGB(0,255,0),2,CV_AA, 0 );
cvLine(dst,pt3,pt4,CV_RGB(0,255,0),2,CV_AA, 0 );
return 0;
}
/*** declarations for OpenCV */
IplImage *current_frame_rgb,grid;
IplImage *current_frame_gray;
IplImage *chessBoard_Img;
int Thresholdness = 120;
int image_width = 320;
int image_height = 240;//图像长宽指定，在启动摄像头时需自己手动选择，或者在在代码中指定
bool verbose = false;
const int ChessBoardSize_w = 6;
const int ChessBoardSize_h = 7; //棋盘长宽
// Calibration stuff
bool calibration_done = false;
const CvSize ChessBoardSize = cvSize(ChessBoardSize_w,ChessBoardSize_h);
//float SquareWidth = 21.6f; //实际距离 毫米单位 在A4纸上为两厘米
float SquareWidth = 17; //投影实际距离 毫米单位 200
const int NPoints = ChessBoardSize_w*ChessBoardSize_h;
const int NImages = 20; //Number of images to collect
CvPoint2D32f corners[NPoints*NImages];
int corner_count[NImages] ={0};
int captured_frames = 0;
CvMat *intrinsics; //内参数
CvMat *distortion_coeff;
CvMat *rotation_vectors;//旋转向量
CvMat *translation_vectors;//平移向量
CvMat *object_points;
CvMat *point_counts;//点计数
CvMat *image_points;
int find_corners_result =0 ;
FILE * pdata;
FILE *pinput;
void on_mouse( int event, int x, int y, int flags, void* param )
{
if( event == CV_EVENT_LBUTTONDOWN )
{
//calibration_done = true;
}
}
int main() //为何是_tmain()是只是unicode字符集的一个开始函数。
{
CvFont font;
cvInitFont( &font, CV_FONT_VECTOR0,5, 5, 0, 7, 8);
intrinsics = cvCreateMat(3,3,CV_32FC1);
distortion_coeff = cvCreateMat(1,4,CV_32FC1);
rotation_vectors = cvCreateMat(NImages,3,CV_32FC1);
translation_vectors = cvCreateMat(NImages,3,CV_32FC1);
point_counts = cvCreateMat(NImages,1,CV_32SC1);
object_points = cvCreateMat(NImages*NPoints,3,CV_32FC1);
image_points = cvCreateMat(NImages*NPoints,2,CV_32FC1);
// Function to fill in the real-world points of the checkerboard
InitCorners3D(object_points, ChessBoardSize, NImages, SquareWidth);
CvCapture* capture = 0;
/////////////////////////////////////////////////////////////////////////////////////
// Initialize all of the IplImage structures
current_frame_rgb = cvCreateImage(cvSize(image_width, image_height), IPL_DEPTH_8U, 3);
IplImage *current_frame_rgb2 = cvCreateImage(cvSize(image_width, image_height), IPL_DEPTH_8U, 3);
current_frame_gray = cvCreateImage(cvSize(image_width, image_height), IPL_DEPTH_8U, 1);
chessBoard_Img = cvCreateImage(cvSize(image_width, image_height), IPL_DEPTH_8U, 3);
current_frame_rgb2->origin = chessBoard_Img->origin = current_frame_gray->origin = current_frame_rgb->origin = 1;
makeChessBoard();
cvNamedWindow( "result", 0);
cvNamedWindow( "Window 0", 0);
cvNamedWindow( "grid", 0);
cvMoveWindow( "grid", 100,100);
cvSetMouseCallback( "Window 0", on_mouse, 0 );
cvCreateTrackbar("Thresholdness","Window 0",&Thresholdness, 255,0);
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
int cam_count;
//仅仅获取摄像头数目
cam_count = CCameraDS::CameraCount();
printf("There are %d cameras.\n", cam_count);
//获取所有摄像头的名称
for(int i=0; i < cam_count; i++)
{
char camera_name[1024];
int retval = CCameraDS::CameraName(i, camera_name, sizeof(camera_name) );
if(retval >0)
printf("Camera #%d's Name is '%s'.\n", i, camera_name);
else
printf("Can not get Camera #%d's name.\n", i);
}
if(cam_count==0)
return -1;
CCameraDS camera;
//打开第一个摄像头
//if(! camera.OpenCamera(0, true)) //弹出属性选择窗口
if(! camera.OpenCamera(1, false, 320,240)) //不弹出属性选择窗口，用代码制定图像宽和高
{
fprintf(stderr, "Can not open camera.\n");
return -1;
}
cvNamedWindow("camera");
while(!calibration_done)
{
while (captured_frames<NImages)
{
//获取一帧
current_frame_rgb = camera.QueryFrame();
//显示
if (!current_frame_rgb)
{
break;
}
cvShowImage("camera",current_frame_rgb);
cvCopy(current_frame_rgb,current_frame_rgb2);
cvCvtColor(current_frame_rgb, current_frame_gray, CV_BGR2GRAY);
//cvThreshold(current_frame_gray,current_frame_gray,Thresholdness,255,CV_THRESH_BINARY);
//cvThreshold(current_frame_gray,current_frame_gray,150,255,CV_THRESH_BINARY_INV);
find_corners_result = cvFindChessboardCorners(current_frame_gray,ChessBoardSize,&corners[captured_frames*NPoints],&corner_count[captured_frames],0);
cvDrawChessboardCorners(current_frame_rgb2, ChessBoardSize, &corners[captured_frames*NPoints], NPoints, find_corners_result);
cvShowImage("Window 0",current_frame_rgb2);
cvShowImage("grid",chessBoard_Img);
if(find_corners_result==1)
{
cvWaitKey(2000);
cvSaveImage("c:\\hardyinCV.jpg",current_frame_rgb2);
captured_frames++;
}
//cvShowImage("result",current_frame_gray);
//intrinsics->data.fl[0] = 256.8093262; //fx
//intrinsics->data.fl[2] = 160.2826538; //cx
//intrinsics->data.fl[4] = 254.7511139; //fy
//intrinsics->data.fl[5] = 127.6264572; //cy
float temp1,temp2,temp3,temp4;
pinput = fopen("input.txt","r");
fscanf(pinput,"%f\n",&temp1);
fscanf(pinput,"%f\n",&temp2);
fscanf(pinput,"%f\n",&temp3);
fscanf(pinput,"%f\n",&temp4);
intrinsics->data.fl[0] = temp1; //fx
intrinsics->data.fl[2] = temp2; //cx
intrinsics->data.fl[4] = temp3; //fy
intrinsics->data.fl[5] = temp4; //cy
fclose(pinput);
intrinsics->data.fl[1] = 0;
intrinsics->data.fl[3] = 0;
intrinsics->data.fl[6] = 0;
intrinsics->data.fl[7] = 0;
intrinsics->data.fl[8] = 1;
distortion_coeff->data.fl[0] = -0.193740; //k1
distortion_coeff->data.fl[1] = -0.378588; //k2
distortion_coeff->data.fl[2] = 0.028980; //p1
distortion_coeff->data.fl[3] = 0.008136; //p2
cvWaitKey(40);
find_corners_result = 0;
}
// if (find_corners_result !=0)
{
printf(" ");
cvSetData( image_points, corners, sizeof(CvPoint2D32f));
cvSetData( point_counts, &corner_count, sizeof(int));
cvCalibrateCamera2( object_points,image_points,point_counts,cvSize(image_width,image_height),intrinsics,distortion_coeff,rotation_vectors,translation_vectors,0);
// [fx 0 cx; 0 fy cy; 0 0 1].
// cvUndistort2(current_frame_rgb,current_frame_rgb,intrinsics,distortion_coeff);
// cvShowImage("result",current_frame_rgb);
cvUndistort2(current_frame_rgb,current_frame_rgb2,intrinsics,distortion_coeff);
cvShowImage("result",current_frame_rgb2);
float intr[3][3] = {0.0};
float dist[4] = {0.0};
float tranv[3] = {0.0};
float rotv[3] = {0.0};
for ( int i = 0; i < 3; i++)
{
for ( int j = 0; j < 3; j++)
{
intr[i][j] = ((float*)(intrinsics->data.ptr + intrinsics->step*i))[j];
}
dist[i] = ((float*)(distortion_coeff->data.ptr))[i];
tranv[i] = ((float*)(translation_vectors->data.ptr))[i];
rotv[i] = ((float*)(rotation_vectors->data.ptr))[i];
}
dist[3] = ((float*)(distortion_coeff->data.ptr))[3];
printf("----------------------------------------- ");
printf("INTRINSIC MATRIX: ");
printf("[ %6.4f %6.4f %6.4f ] ", intr[0][0], intr[0][1], intr[0][2]);
printf("[ %6.4f %6.4f %6.4f ] ", intr[1][0], intr[1][1], intr[1][2]);
printf("[ %6.4f %6.4f %6.4f ] ", intr[2][0], intr[2][1], intr[2][2]);
printf("----------------------------------------- ");
printf("DISTORTION VECTOR: ");
printf("[ %6.4f %6.4f %6.4f %6.4f ] ", dist[0], dist[1], dist[2], dist[3]);
printf("----------------------------------------- ");
printf("ROTATION VECTOR: ");
printf("[ %6.4f %6.4f %6.4f ] ", rotv[0], rotv[1], rotv[2]);
printf("TRANSLATION VECTOR: ");
printf("[ %6.4f %6.4f %6.4f ] ", tranv[0], tranv[1], tranv[2]);
printf("----------------------------------------- ");
pdata = fopen("data.txt","a");
fprintf(pdata,"%f\n",intr[0][0]);
fprintf(pdata,"%f\n",intr[0][2]);
fprintf(pdata,"%f\n",intr[1][1]);
fprintf(pdata,"%f\n",intr[1][2]);
fprintf(pdata,"%f\n",dist[0]);
fprintf(pdata,"%f\n",dist[1]);
fprintf(pdata,"%f\n",dist[2]);
fprintf(pdata,"%f\n",dist[3]);
fprintf(pdata,"%f\n",rotv[0]);
fprintf(pdata,"%f\n",rotv[1]);
fprintf(pdata,"%f\n",rotv[2]);
fprintf(pdata,"%f\n",tranv[0]);
fprintf(pdata,"%f\n",tranv[1]);
fprintf(pdata,"%f\n",tranv[2]);
fprintf(pdata,"%f\n",tranv[3]);
fprintf(pdata,"%s\n","#");
fclose(pdata);
pinput = fopen("input.txt","w");
fprintf(pinput,"%f\n",intr[0][0]);
fprintf(pinput,"%f\n",intr[0][2]);
fprintf(pinput,"%f\n",intr[1][1]);
fprintf(pinput,"%f\n",intr[1][2]);
fclose(pinput);
cvWaitKey(0);
calibration_done = true;
}
}
camera.CloseCamera(); //可不调用此函数，CCameraDS析构时会自动关闭摄像头
cvDestroyWindow("camera");
exit(0);
cvDestroyAllWindows();
return 0;
}
void InitCorners3D(CvMat *Corners3D, CvSize ChessBoardSize, int NImages, float SquareSize)
{
int CurrentImage = 0;
int CurrentRow = 0;
int CurrentColumn = 0;
int NPoints = ChessBoardSize.height*ChessBoardSize.width;
float * temppoints = new float[NImages*NPoints*3];
// for now, assuming we're row-scanning
for (CurrentImage = 0 ; CurrentImage < NImages ; CurrentImage++)
{
for (CurrentRow = 0; CurrentRow < ChessBoardSize.height; CurrentRow++)
{
for (CurrentColumn = 0; CurrentColumn < ChessBoardSize.width; CurrentColumn++)
{
temppoints[(CurrentImage*NPoints*3)+(CurrentRow*ChessBoardSize.width + CurrentColumn)*3]=(float)CurrentRow*SquareSize;
temppoints[(CurrentImage*NPoints*3)+(CurrentRow*ChessBoardSize.width + CurrentColumn)*3+1]=(float)CurrentColumn*SquareSize;
temppoints[(CurrentImage*NPoints*3)+(CurrentRow*ChessBoardSize.width + CurrentColumn)*3+2]=0.f;
}
}
}
(*Corners3D) = cvMat(NImages*NPoints,3,CV_32FC1, temppoints);
}
int myFindChessboardCorners( const void* image, CvSize pattern_size,CvPoint2D32f* corners, int* corner_count,int flags )
{
IplImage* eig = cvCreateImage( cvGetSize(image), 32, 1 );
IplImage* temp = cvCreateImage( cvGetSize(image), 32, 1 );
double quality = 0.01;
double min_distance = 5;
int win_size =10;
int count = pattern_size.width * pattern_size.height;
cvGoodFeaturesToTrack( image, eig, temp, corners, &count,quality, min_distance, 0, 3, 0, 0.04 );
cvFindCornerSubPix( image, corners, count,
cvSize(win_size,win_size), cvSize(-1,-1),
cvTermCriteria(CV_TERMCRIT_ITER|CV_TERMCRIT_EPS,20,0.03));
cvReleaseImage( &eig );
cvReleaseImage( &temp );
return 1;
}
void makeChessBoard()
{
CvScalar e;
e.val[0] =255;
e.val[1] =255;
e.val[2] =255;
cvSet(chessBoard_Img,e,0);
for(int i = 0;i<ChessBoardSize.width+1;i++)
{
for(int j = 0;j<ChessBoardSize.height+1;j++)
{
int w =(image_width)/2/(ChessBoardSize.width);
int h = w; //(image_height)/2/(ChessBoardSize.height);
int ii = i+1;
int iii = ii+1;
int jj =j+1;
int jjj =jj+1;
int s_x = image_width/6;
if((i+j)%2==1)
{
cvRectangle( chessBoard_Img, cvPoint(w*i+s_x,h*j+s_x),cvPoint(w*ii-1+s_x,h*jj-1+s_x), CV_RGB(0,0,0),CV_FILLED, 8, 0 );
}
}
}
}