我无法将 calcOpticalFlowPyrLK 与 MatOfPoint2f 一起使用。我声明我的类型如下:
private Mat mPreviousGray; // previous gray-level image
private List<MatOfPoint2f> points; // tracked features
private MatOfPoint initial; // initial position of tracked points
并使用以下内容来查找和跟踪功能
(我的代码基于 Robert Laganiere 编写的 C++ 示例光流应用程序。)
// Called whenever a new frame m is captured
private void OpticalFlow(Mat m, int maxDetectionCount, double qualityLevel,
double minDistance) {
if (points.get(0).total() < maxDetectionCount/2) // Check if new points need to be added
{
// maxDetectionCount = 500
// qualityLevel = 0.01
// minDistance = 10
Imgproc.goodFeaturesToTrack(m, initial, maxDetectionCount, qualityLevel, minDistance);
// add the detected features to the currently tracked features
points.get(0).push_back(initial);
// Have checked length of points.get(0), is not zero.
}
// for first image of the sequence
if(mPreviousGray.empty())
m.copyTo(mPreviousGray);
if( points.get(0).total() > 0 ) // EMG - 09/22/11 - fix optical flow crashing bug
{
// 2. track features
Video.calcOpticalFlowPyrLK(mPreviousGray, m, // 2 consecutive images
points.get(0), // input point position in first image
points.get(1), // output point postion in the second image
status, // tracking success
error); // tracking error
}
...
m.copyTo(mPreviousGray);
...
}
之前,变量points
是类型List<List<Point>>
我将通过实例化 MatOfPoint2f 来在类型之间进行转换fromList
并将其传递给 calcOpticalFlowPyrLK。
但是,我不想再这样做,因为这种从列表到列表的转换丢失了点之间的对应关系initial
and points
。我想保留这种对应关系,因此我可以通过同时迭代两个矩阵中的项目来绘制光流线。
不幸的是,现在我遇到以下断言失败:
09-24 10:04:30.400: E/cv::error()(8216): OpenCV Error: Assertion failed ((npoints = prevPtsMat.checkVector(2, CV_32F, true)) >= 0) in void cv::calcOpticalFlowPyrLK(const cv::_InputArray&, const cv::_InputArray&, const cv::_InputArray&, const cv::_OutputArray&, const cv::_OutputArray&, const cv::_OutputArray&, cv::Size, int, cv::TermCriteria, int, double), file X:\Dev\git\opencv-2.4\modules\video\src\lkpyramid.cpp, line 593
09-24 10:04:30.400: E/AndroidRuntime(8216): FATAL EXCEPTION: Thread-321
09-24 10:04:30.400: E/AndroidRuntime(8216): CvException [org.opencv.core.CvException: X:\Dev\git\opencv-2.4\modules\video\src\lkpyramid.cpp:593: error: (-215) (npoints = prevPtsMat.checkVector(2, CV_32F, true)) >= 0 in function void cv::calcOpticalFlowPyrLK(const cv::_InputArray&, const cv::_InputArray&, const cv::_InputArray&, const cv::_OutputArray&, const cv::_OutputArray&, const cv::_OutputArray&, cv::Size, int, cv::TermCriteria, int, double)
09-24 10:04:30.400: E/AndroidRuntime(8216): ]
09-24 10:04:30.400: E/AndroidRuntime(8216): at org.opencv.video.Video.calcOpticalFlowPyrLK_2(Native Method)
09-24 10:04:30.400: E/AndroidRuntime(8216): at org.opencv.video.Video.calcOpticalFlowPyrLK(Video.java:445)
奇怪的是,如果我在调用 calcOpticalFlowPyrLK 之前自己添加此断言,它不会失败。
我希望有人可以帮助我找出真正的问题所在,以及如何保留帧之间跟踪点之间的这种关系。
Edit:我已经发现需要采取哪些措施来避免此断言错误,然后应用程序就会正常运行,但是:
- 我不知道why.
- 我现在对于 Calib3d.solvePnP 有类似的问题,但是将 ConvertTo 应用于 imagePoints 和 objectPoints 并不能解决这里的问题,也不能解决
CvType.CV_32FC2
, nor CvType.CV_32F
or CvType.CV_64F
纠正断言失败的情况calcOpticalFlowPyrLK
,我变了points.get(0).push_back(initial);
至以下内容:
Imgproc.goodFeaturesToTrack(m, initial, maxDetectionCount, qualityLevel, minDistance);
MatOfPoint2f initial2f = new MatOfPoint2f();
initial.convertTo(initial2f, CvType.CV_32FC2);
// add the detected features to the currently tracked features
trackedpoints.get(0).push_back(initial2f);
所以我的问题变成了:有人可以为我解释一下一般情况,以便我知道如何使用 Calib3d.solvePnP 解决我的问题吗?