farneback optical flow in opencv for java

edit

yes, look here

Thank you very much!

Finally i installed openCV successfully. However it is so hard to define the variables and to use the function..Is there any manual which can help very beginners for java?

hey, nice to hear, that you got it running now ;)

unfortunately, there are no real beginner-tutorials for java. there are some for android, but apart from the same language, pretty much different situation.

I used to use openCv in c++ and it was awesome. Know i can really to something! Let's say i am trying to to the following:

import org.opencv.core.Core;

import org.opencv.core.CvType; import org.opencv.core.Mat;

public class openCvHello { public static void main( String[] args ) { // System.loadLibrary( Core.NATIVE_LIBRARY_NAME );

   System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
    Mat mat = Mat.eye( 3, 3, CvType.CV_8UC1 );

   Mat prev=Mat.ones( 3, 3, CvType.CV_8UC1 );
   Mat next=Mat.ones( 3, 3, CvType.CV_8UC1 );
   Mat flow=Mat.ones( 3, 3, CvType.CV_8UC1 );
   calcOpticalFlowFarneback(prev,next,flow,0.5,1, 1, 1, 7,
           1.5,1);
  System.out.println( "mat = " + mat.dump() );

} }

However, i am getting this error:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: The method calcOpticalFlowFarneback(Mat, Mat, Mat, double, int, int, int, int, double, int) is undefined for the type openCvHello

at openCvHello.main(openCvHello.java:17). 
   Can you help me please!! 
   You will be my hero!

hey ;)

• it should be Video.calcOpticalFlowFarneback(...) // there's no 'free' functions in java, the replacement for this are static members of a (static, again) module class, Highgui.imread(...); Imgproc.cvtColor(...); and such, you'll get the picture..

• from the doc page, again: flow - computed flow image that has the same size as prev and type CV_32FC2.

  so the type for your flow mat is wrong here, too. should be CvType.CV_32FC2 instead. that 'flow' matrix will hold the x and y movement for each pixel

also, chuckle a bit about things being peculiar in java here