Android应用程序跟踪点：Video.calcOpticalFlow（...）方法不能正常工作？ [英] Android App Tracking Points: Video.calcOpticalFlow(...) method not working properly?
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问题描述
我目前正在建立一个Android应用程序使用的OpenCV，允许用户跟踪使用智能手机的摄像头移动的物体点。类似code C ++中这不正是我要寻找可以在下面的链接中找到：的光流法C ++示例code
我一直在谷歌搜索和计算器四处寻找，但我仍然无法弄清楚，为什么我的code不工作。我能我每次美元一定当场p $ PSS时间放在屏幕上点，但似乎分，甚至一动不动，我在镜头前移动对象。用于计算opitcal流的方法，如下：
无效org.opencv.video.Video.calcOpticalFlowPyrLK（太prevImg，垫nextImg，MatOfPoint2f prevPts，MatOfPoint2f nextPts，MatOfByte状态，MatOfFloat ERR）
我相信我通过计算连续图像的光流所需的确切参数，但由于某种原因，它不工作。下面是我的code：
包org.opencv.UActivity;// include文件
...公共类U2Activity扩展活动实现OnTouchListener，CvCameraViewListener2 { 私有静态最后弦乐TAG =OCVSample ::活动; 私人垫nextGray，Rscale;
私人垫prevGray;
私人MatOfPoint2f prev2D，next2D;
私人MatOfByte状态;
私人MatOfFloat犯错;
私人标色; 私人CameraBridgeViewBase mOpenCvCameraView;
私人BaseLoaderCallback mLoaderCallback =新BaseLoaderCallback（本）{
@覆盖
公共无效onManagerConnected（INT状态）{
开关（状态）{
案例LoaderCallbackInterface.SUCCESS：
{
Log.i（TAG的OpenCV加载成功）;
mOpenCvCameraView.enableView（）;
mOpenCvCameraView.setOnTouchListener（U2Activity.this）;
}打破;
默认：
{
super.onManagerConnected（状态）;
}打破;
}
}
}; 公共U2Activity（）{
Log.i（TAG，实例化新的+ this.getClass（））;
} / **当第一次创建活动调用。 * /
@覆盖
公共无效的onCreate（捆绑savedInstanceState）{
Log.i（TAG叫的onCreate）;
super.onCreate（savedInstanceState）;
requestWindowFeature（Window.FEATURE_NO_TITLE）;
。getWindow（）addFlags（WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON）; 的setContentView（R.layout.u2_surface_view）; mOpenCvCameraView =（CameraBridgeViewBase）findViewById（R.id.u2_activity_surface_view）;
mOpenCvCameraView.setCvCameraViewListener（本）; 颜色=新标量（0，255，0）; } @覆盖
公共无效的onPause（）
{
super.onPause（）;
如果（mOpenCvCameraView！= NULL）
mOpenCvCameraView.disableView（）;
} @覆盖
公共无效onResume（）
{
super.onResume（）;
OpenCVLoader.initAsync（OpenCVLoader.OPENCV_VERSION_2_4_3，对此，mLoaderCallback）;
} 公共无效的onDestroy（）{
super.onDestroy（）;
如果（mOpenCvCameraView！= NULL）
mOpenCvCameraView.disableView（）;
} 公共无效onCameraViewStarted（INT宽度，高度INT）{
nextGray =新垫（高度，宽度，CvType.CV_8UC1）; // unsigned char型
Rscale =新垫（高度，宽度，CvType.CV_8UC1）;
prevGray =新垫（高度，宽度，CvType.CV_8UC1）; prev2D =新MatOfPoint2f（新点（））;
next2D =新MatOfPoint2f（新点（））;
状态=新MatOfByte（）;
ERR =新MatOfFloat（）;
} 公共无效onCameraViewStopped（）{
nextGray.release（）;
Rscale.release（）;
} 公共布尔onTouch（视图V，MotionEvent事件）{ INT COLS = nextGray.cols（）;
INT行= nextGray.rows（）; INT xOffset =（mOpenCvCameraView.getWidth（） - COLS）/ 2;
INT yOffset =（mOpenCvCameraView.getHeight（） - 行）/ 2; INT X =（INT）event.getX（） - xOffset;
INT Y =（int）的event.getY（） - yOffset; 如果（（X小于0）||（Y℃下）||（X＆GT; COLS）||（Y＆GT;行））返回false; prev2D.push_back（新MatOfPoint2f（新点（（双）X，（双）Y）））;
next2D.push_back（新MatOfPoint2f（新点（）））; 返回false; //不需要后续触摸事件
} 公共垫onCameraFrame（CvCameraViewFrame inputFrame）{
nextGray = inputFrame.gray（）; //获取当前图像
Rscale = nextGray; //使当前图像的副本
如果（prevGray.empty（））prevGray = nextGray; //在启动时没有prevGray。复制当前。
Video.calcOpticalFlowPyrLK（prevGray，nextGray，prev2D，next2D，状态，ERR）; // Calc的光流
prevGray = nextGray; //覆盖原有图像（prevGray）
prev2D = next2D; //覆盖原有点坐标
的for（int i = 0; I＆LT; next2D.toArray（）长;我++）{//绘制点在图像中
Core.circle（Rscale，next2D.toArray（）[I]，3，颜色）;
}
返回Rscale;
}
}
解决方案
解决
我改了：
prevGray = nextGray;
prev2D = next2D;
到
nextGray.copyTo（prevGray）;
next2D.copyTo（prev2D）;
我希望它能帮助任何人都遇到类似的问题。
I am currently trying to create an Android App using OpenCV that allows the user to track points of moving objects using the smartphone camera. An analogous code in C++ that does exactly what I am looking for can be found in the following link: OpticalFlow C++ Sample Code
I have been Googling and looking around in StackOverflow, but I still can't figure out why my code is not working. I am able to place points on the screen every time I press on a certain spot, but the points seem motionless even as I move objects in front of the camera. The method used to calculate the opitcal flow is the following:
void org.opencv.video.Video.calcOpticalFlowPyrLK(Mat prevImg, Mat nextImg, MatOfPoint2f prevPts, MatOfPoint2f nextPts, MatOfByte status, MatOfFloat err)
I believe I am passing the exact parameters needed to calculate the optical flow of consecutive images, but for some reason it's not working. Below is my code:
package org.opencv.UActivity;
//INCLUDE FILES
...
public class U2Activity extends Activity implements OnTouchListener,CvCameraViewListener2{
private static final String TAG = "OCVSample::Activity";
private Mat nextGray,Rscale;
private Mat prevGray;
private MatOfPoint2f prev2D,next2D;
private MatOfByte status;
private MatOfFloat err;
private Scalar color;
private CameraBridgeViewBase mOpenCvCameraView;
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
{
Log.i(TAG, "OpenCV loaded successfully");
mOpenCvCameraView.enableView();
mOpenCvCameraView.setOnTouchListener(U2Activity.this);
} break;
default:
{
super.onManagerConnected(status);
} break;
}
}
};
public U2Activity() {
Log.i(TAG, "Instantiated new " + this.getClass());
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
Log.i(TAG, "called onCreate");
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setContentView(R.layout.u2_surface_view);
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.u2_activity_surface_view);
mOpenCvCameraView.setCvCameraViewListener(this);
color = new Scalar(0, 255, 0);
}
@Override
public void onPause()
{
super.onPause();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
@Override
public void onResume()
{
super.onResume();
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_3, this, mLoaderCallback);
}
public void onDestroy() {
super.onDestroy();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
public void onCameraViewStarted(int width, int height) {
nextGray = new Mat(height, width, CvType.CV_8UC1); //unsigned char
Rscale = new Mat(height, width, CvType.CV_8UC1);
prevGray = new Mat(height, width, CvType.CV_8UC1);
prev2D = new MatOfPoint2f(new Point());
next2D = new MatOfPoint2f(new Point());
status = new MatOfByte();
err = new MatOfFloat();
}
public void onCameraViewStopped() {
nextGray.release();
Rscale.release();
}
public boolean onTouch(View v, MotionEvent event) {
int cols = nextGray.cols();
int rows = nextGray.rows();
int xOffset = (mOpenCvCameraView.getWidth() - cols) / 2;
int yOffset = (mOpenCvCameraView.getHeight() - rows) / 2;
int x = (int)event.getX() - xOffset;
int y = (int)event.getY() - yOffset;
if ((x < 0) || (y < 0) || (x > cols) || (y > rows)) return false;
prev2D.push_back(new MatOfPoint2f(new Point((double)x,(double)y)));
next2D.push_back(new MatOfPoint2f(new Point()));
return false; // don't need subsequent touch events
}
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
nextGray = inputFrame.gray(); //get current image
Rscale = nextGray; //make a copy of current image
if(prevGray.empty()) prevGray = nextGray; //on start there is no prevGray. Copy current.
Video.calcOpticalFlowPyrLK(prevGray,nextGray,prev2D,next2D,status,err); //Calc the Optical Flow
prevGray = nextGray; //Overwrite old Image (prevGray)
prev2D = next2D; //Overwrite old point coordinates
for(int i=0;i<next2D.toArray().length;i++){ //Draw the points in the image
Core.circle(Rscale, next2D.toArray()[i], 3, color);
}
return Rscale;
}
}
解决方案
SOLVED:
I changed:
prevGray = nextGray;
prev2D = next2D;
to:
nextGray.copyTo(prevGray);
next2D.copyTo(prev2D);
I hope it helps anyone encountering similar problems.
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