Skip vector <Point2f> for getAffineTransform

Question

I am trying to calculate the affine transformation between two consecutive frames from a video. So I found the functions and got consistent points in two frames.

    FastFeatureDetector detector;

    vector<Keypoints> frame1_features;
    vector<Keypoints> frame2_features;

    detector.detect(frame1 , frame1_features , Mat());
    detector.detect(frame2 , frame2_features , Mat());

    vector<Point2f> features1;  //matched points in 1st image  
    vector<Point2f> features2;  //matched points in 2nd image

    for(int i = 0;i<frame2_features.size() && i<frame1_features.size();++i )
    {

            double diff;
            diff = pow((frame1.at<uchar>(frame1_features[i].pt) - frame2.at<uchar>(frame2_features[i].pt)) , 2);

            if(diff<SSD)    //SSD is sum of squared differences between two image regions
            {
                feature1.push_back(frame1_features[i].pt);
                feature2.push_back(frame2_features[i].pt);
            }
    }

    Mat affine = getAffineTransform(features1 , features2);

The last line displays the following error:

    OpenCV Error: Assertion failed (src.checkVector(2, CV_32F) == 3 && dst.checkVector(2, CV_32F) == 3) in getAffineTransform

Can someone tell me how to calculate an affine transformation with a set of matching points between two frames?

Answer 1

, 3 . , ( ).
findHomography() - (http://docs.opencv.org/modules/calib3d/doc/camera_calibration_and_3d_reconstruction.html#findhomography).
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, - , .
, (, , ), . , findHomography(features1 , features2, CV_RANSAC) getAffineTransform(features1 , features2).
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Answer 2

, - .

int checkVector(int elemChannels,int depth) //

N, 1- (N x ptdim) ptdim- (1 x N) (N x 1); .

; http://docs.opencv.org/modules/imgproc/doc/geometric_transformations.html#getaffinetransform: .

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