Question

我有一个问题，我真的不知道如何解决。情况是我有一张照片，在这张照片中我有一个ROI（一个大的矩形）。在这个矩形内，我有X个较小的ROI：s。

然后我在更大的投资回报率上使用getPerspectiveTransform()方法。我当时想要做的是将这个矩阵应用于较小的ROI：s依次扭曲它们，但使用较大ROI的矩阵。我想这样做的原因基本上是因为我想要保留经线前我已经得到的边界。如果有任何方法可以扭曲更大的投资回报率并保持其内部的界限（即保持较小的投资回报率），这将是非常有帮助的！

无论如何，这是我尝试过的，以及它产生的结果：

vector<Mat> warpSmallerRoi( vector<Rect> smallerRoi ) { 

    vector<Mat> quad;

    for( int i = 0; i < smallerRoi.size(); ++ i ) {
        Mat wholeQuad;

        wholeQuad = Mat::zeros( originalImage(smallerRoi[i]).rows, originalImage(smallerRoi[i]).cols, CV_8UC1 );
        vector<Point2f> largerRoiCorners;
        vector<Point2f> quadPoints;

        // Takes the corners from the first smaller ROI and the last smaller ROI, represents the bigger ROI
        largerRoiCorners.push_back( Point2f( smallerRoi[0].tl().x, smallerRoi[0].tl().y ) ); // Top left
        largerRoiCorners.push_back( Point2f( smallerRoi[ smallerRoi.size() - 1 ].br().x, smallerRoi[ smallerRoi.size() - 1  ].tl().y ) ); // Top right
        largerRoiCorners.push_back( Point2f( smallerRoi[ smallerRoi.size() - 1 ].br().x, smallerRoi[ smallerRoi.size() - 1  ].br().y ) ); // Bottom right
        largerRoiCorners.push_back( Point2f( smallerRoi[0].tl().x, smallerRoi[0].br().y ) ); // Bottom left

        quadPoints.push_back( Point2f(0, 0) );
        quadPoints.push_back( Point2f(wholeQuad.cols, 0) );
        quadPoints.push_back( Point2f( wholeQuad.cols, wholeQuad.rows ) );
        quadPoints.push_back( Point2f(0, wholeQuad.rows) );

        // Transform matrix for the larger ROI, this warps into a perfect result.
        Mat largerRoiTransformMatrix = getPerspectiveTransform( largerRoiCorners, quadPoints );

        //Corners of the smaller ROI
        vector<Point2f> corners;
        corners.push_back( Point2f( smallerRoi[i].tl().x, smallerRoi[i].tl().y ) ); // Top left
        corners.push_back( Point2f( smallerRoi[i].br().x, smallerRoi[i].tl().y ) ); // Top right
        corners.push_back( Point2f( smallerRoi[i].br().x, smallerRoi[i].br().y )); // Bottom right
        corners.push_back( Point2f( smallerRoi[i].tl().x, smallerRoi[i].br().y ) ); // Bottom left

        Mat transformMatrix = getPerspectiveTransform( corners, quadPoints );

        /* This part is just experimental and does not work all the time, it works well sometimes though 
           Uses the pars from the larger ROI transform matrix and applies it on the smaller ROI
           then warps it.
        */
        transformMatrix.at<double>(1,0) = largerRoiTransformMatrix.at<double>(1,0);
        transformMatrix.at<double>(1,1) = largerRoiTransformMatrix.at<double>(1,1);
        transformMatrix.at<double>(1,2) = largerRoiTransformMatrix.at<double>(1,2);

        transformMatrix.at<double>(2,0) = largerRoiTransformMatrix.at<double>(2,0);
        transformMatrix.at<double>(2,1) = largerRoiTransformMatrix.at<double>(2,1);
        transformMatrix.at<double>(2,2) = largerRoiTransformMatrix.at<double>(2,2);

        // Warps the 
        warpPerspective( plateRgb, wholeQuad, transformMatrix, wholeQuad.size() );
        quad.push_back(wholeQuad);
    }
    return quad;
}

此功能有时会起作用，特别是当较大的ROI已经非常直线时（我想这是因为我的替换与原始值没有那么大差别）。例如：

自：

Smaller ROI without warp