Fast Corner Detection

在机器视觉里面，角点检测有好几种；其中，属Fast Corner Detection 比较好用。下面，介绍Fast Corner Detection源码。

读者可以下载自己所需要的版本。下面以Opencv 版本为例。
由于Opencv版本的问题，会遇到如错误。

fatal error C1083: 无法打开包括文件:“cxtypes.h”: No such file or directory

解决:

代码块

将#include <cxtypes.h>

改成

#include “cv.h”

#include “cxcore.h”

#include “highgui.h”

下面，附加上main.cpp

代码块

include <cvaux.h>
#include <highgui.h>

#include "cvfast.h"

int main(int argc, char* argv[])
{
    ////////////////////////////////////////////////////////////////////////////////
    //
    // Process command line arguments
    //

    int numArgs = argc;

    //char* OutFileName = argv[numArgs-1];
    //char* InFileName = argv[numArgs-2];
    const char* OutFileName="1model_out.jpg";
    const char* InFileName="1model.jpg";

    int inFASTThreshhold = 20;
    int inNpixels = 9;
    int inModeCrossesVsList = 1;
    int inNonMaxSuppression  = 0;


    int numRemainingArgs = numArgs - 3;

    /*if( numArgs <=2 ) {
        printf( "Need at least 2 arguments: input_file output_file\n" );
        printf( "Re-run with /? to see usage\n" );
    }

    if( numArgs < 3 ) {
        printf( "Perform  FAST feature detection on an image.\n"
                "\n"
                "Usage:\n"
                "input_image \t Input filename\n"
                "output_file \t Output filename\n"
                "/l \t\t Output a list of corners (instead of an image)\n"
                "/t X \t\t Set threshold to X. Default is 20\n"
                "/n X \t\t Use X point fast (allowed range is 9--12, default is 9)\n"
                "/s \t\t Perform nonmaximal suppression\n");
        return 0;
    }

    for( int j=1; j <= numRemainingArgs; j++ )
    {
        if( !strcmp( argv[j], "/l" ) ) {
            inModeCrossesVsList = 2;
        }
        else if( !strcmp( argv[j], "/s" ) ) {
            inNonMaxSuppression = 1;
        }
        else if( !strcmp( argv[j], "/t" ) ) {
            j++;
            inFASTThreshhold = atoi( argv[j] );
        }
        else if( !strcmp( argv[j], "/n" ) ) {
            j++;
            inNpixels = atoi( argv[j] );
            if( inNpixels > 12 || inNpixels < 9 ) {
                printf( "X point fast requires 8 < X  < 13, not %d\n", inNpixels );
                return( 0 );
            }
        }
        else {
            printf( "Unrecognized arguments (%s), re-run with /?\n", argv[j] );
            return( 0 );
        }
    }
    */
    ////////////////////////////////////////////////////////////////////////////////
    //
    //Load an image in to 8 bit grey cvd image using IPL
    //

    IplImage* I_in = cvLoadImage( InFileName, -1 );
    IplImage* IGray = cvCreateImage( cvGetSize( I_in ), IPL_DEPTH_8U, 1);
    cvCvtColor( I_in, IGray, CV_RGB2GRAY );

    CvPoint* corners;
    int numCorners;

    cvCornerFast(IGray, inFASTThreshhold, inNpixels, inNonMaxSuppression, &numCorners, & corners);


    if ( inModeCrossesVsList == 1 ) 
    {
        // Put they grey image in to a colour buffer and draw on it
        cvCvtColor( IGray, I_in, CV_GRAY2RGB ); // Instead of iplColorToGray( Icanvas, IcanvasGray );
        for(int i=0; i < numCorners; i++ ) 
        {
            cvLine( I_in, 
                    cvPoint( corners[i].x-1, corners[i].y ), 
                    cvPoint( corners[i].x+1, corners[i].y ), 
                    CV_RGB(255,0,0) );
            cvLine( I_in, 
                    cvPoint( corners[i].x, corners[i].y-1 ), 
                    cvPoint( corners[i].x, corners[i].y+1 ), 
                    CV_RGB(255,0,0) );
        }
        cvSaveImage( OutFileName, I_in );
    }
    else if (inModeCrossesVsList == 2 ) 
    {
        // Print to txt file.
        printf( "Saving list of corners to file %s...", OutFileName );
        FILE* fp = fopen( OutFileName, "w" );
        for(int i=0; i < numCorners; i++ ) {
            fprintf( fp, "%i %i\n", corners[i].x, corners[i].y );
        }
        printf( "done.\n" );
        fclose( fp );
    }


}