Question

我试图使用openCV http://code.google.com/p/android-opencv/在Android中实现光流。基本上我想构建类似http://www.youtube.com/watch?v=P_Sjn67jIJY的东西。无论如何，因为我刚开始Android开发可以任何人指导某个地方，以便建立类似视频的那个？我已经安装了opencv端口到android并使用eclipse成功构建了cvcamera示例。谢谢，Thanos

Answer 1

参见斯坦福OpenCV光流link。事情应该以基本相同的方式工作，除非由于1.x与2.x的C与C ++ API问题，调用可能略有不同。

只需编辑CVCamera示例，它应该很快。我让CVCamera工作了大约一个小时后制作了一个实时的人脸检测应用程序。

Answer 2

虽然我也在努力做同样的事情，但现在OpenCV4Android似乎对光流的支持更多了。查看org.opencv.video中的API OpenCV Java documentation 我看到calcOpticalFlowPyrLK和calcOpticalFlowFarneback。我能够使calcOpticalFlowFarneback工作（虽然结果似乎不太好，可能需要调整参数） calcOpticalFlowPyrLK被证明是棘手的。我似乎无法将FeatureDetector类（MatOfKeyPoint）返回的关键点转换为calcOpticalFlowFarneback（MatOfPoint2f）所需的点（{3}}

Answer 3

访问http://opencv.willowgarage.com/wiki/Android2.3.0，OpenCV 2.3.0 Release Candidate对Android有很好的支持。里面有光流......用它

Answer 4

此代码将帮助您获取光学矢量。它会跟踪它们

@覆盖 public Mat onCameraFrame（CvCameraViewFrame inputFrame）{

    mRgba = inputFrame.rgba();
    if (mMOP2fptsPrev.rows() == 0) {

        //Log.d("Baz", "First time opflow");
        // first time through the loop so we need prev and this mats
        // plus prev points
        // get this mat
        Imgproc.cvtColor(mRgba, matOpFlowThis, Imgproc.COLOR_RGBA2GRAY);

        // copy that to prev mat
        matOpFlowThis.copyTo(matOpFlowPrev);

        // get prev corners
        Imgproc.goodFeaturesToTrack(matOpFlowPrev, MOPcorners, iGFFTMax, 0.05, 20);
        mMOP2fptsPrev.fromArray(MOPcorners.toArray());

        // get safe copy of this corners
        mMOP2fptsPrev.copyTo(mMOP2fptsSafe);
        }
    else
        {
        //Log.d("Baz", "Opflow");
        // we've been through before so
        // this mat is valid. Copy it to prev mat
        matOpFlowThis.copyTo(matOpFlowPrev);

        // get this mat
        Imgproc.cvtColor(mRgba, matOpFlowThis, Imgproc.COLOR_RGBA2GRAY);

        // get the corners for this mat
        Imgproc.goodFeaturesToTrack(matOpFlowThis, MOPcorners, iGFFTMax, 0.05, 20);
        mMOP2fptsThis.fromArray(MOPcorners.toArray());

        // retrieve the corners from the prev mat
        // (saves calculating them again)
        mMOP2fptsSafe.copyTo(mMOP2fptsPrev);

        // and save this corners for next time through

        mMOP2fptsThis.copyTo(mMOP2fptsSafe);
        }


    /*
    Parameters:
        prevImg first 8-bit input image
        nextImg second input image
        prevPts vector of 2D points for which the flow needs to be found; point coordinates must be single-precision floating-point numbers.
        nextPts output vector of 2D points (with single-precision floating-point coordinates) containing the calculated new positions of input features in the second image; when OPTFLOW_USE_INITIAL_FLOW flag is passed, the vector must have the same size as in the input.
        status output status vector (of unsigned chars); each element of the vector is set to 1 if the flow for the corresponding features has been found, otherwise, it is set to 0.
        err output vector of errors; each element of the vector is set to an error for the corresponding feature, type of the error measure can be set in flags parameter; if the flow wasn't found then the error is not defined (use the status parameter to find such cases).
    */
    Video.calcOpticalFlowPyrLK(matOpFlowPrev, matOpFlowThis, mMOP2fptsPrev, mMOP2fptsThis, mMOBStatus, mMOFerr);

    cornersPrev = mMOP2fptsPrev.toList();
    cornersThis = mMOP2fptsThis.toList();
    byteStatus = mMOBStatus.toList();

    y = byteStatus.size() - 1;

    for (x = 0; x < y; x++) {
        if (byteStatus.get(x) == 1) {
            pt = cornersThis.get(x);
            pt2 = cornersPrev.get(x);

            Core.circle(mRgba, pt, 5, colorRed, iLineThickness - 1);

            Core.line(mRgba, pt, pt2, colorRed, iLineThickness);
            }
        }

return mRgba;

    }

Android光流与opencv

4 个答案: