Unable to use both cameras of Evo 4G using OpenCV4Android

Question

I'm planning to calculate disparity map by taking two pictures from the two back cameras of Evo 3D. However, I'm able to use only one camera. I tried different index.

index

• 0 gives me left camera (one of the back cameras)
• 1 gives me front camera
• -1 gives me left camera (one of the back cameras).

I once got other camera using -1 index, but it's not working anymore. I'm using CameraBridgeViewBase .

I have seen on Google group of android-opencv that people have successfully used both cameras of Evo 3D phone. I want to know how to do it? Is there some other index? or is there some other way using which I can use this.

PS Native Camera doesn't work. (Android 4.0.3).

Answer 1

The stereoscopic camera ID in Android changed from 2 to 100 with the ICS upgrade. This is the constant used by the Android Camera.open call. I don't think there was ever any official way to get one camera or the other. You can only get one image or both images.

Answer 2

As the above answer suggests, I used 100 as the Camera Index, but it didn't work with OpenCV, so I tried using Android's Camera SDK, but got some errors. But as this is a part of HTC Open Sense SDK, I downloaded it on my Eclipse and used http://www.htcdev.com/devcenter/opensense-sdk/stereoscopic-3d/s3d-sample-code/ . I used the base file of S3D Camera Demo and added few more functions so that I could access the Camera image data and convert it to OpenCV Mat.

So I made few changes in onTouchEvent function in that code, and more code there.

@Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
    //  toggle();
        //Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE); 
        //startActivityForResult(cameraIntent, 1337);
        int bufferSize = width * height * 3;
        byte[] mPreviewBuffer = null;

        // New preview buffer.
        mPreviewBuffer = new byte[bufferSize + 4096];

        // with buffer requires addbuffer.
        camera.addCallbackBuffer(mPreviewBuffer);
        camera.setPreviewCallbackWithBuffer(mCameraCallback);
        break;
    default:
        break;
    }
    return true;
}



private final Camera.PreviewCallback mCameraCallback = new Camera.PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera c) {
    Log.d(TAG, "ON Preview frame");
    img = new Mat(height, width, CvType.CV_8UC1);
    gray = new Mat(height, width, CvType.CV_8UC1);
    img.put(0, 0, data);        



    Imgproc.cvtColor(img, gray, Imgproc.COLOR_YUV420sp2GRAY);
    String pixvalue = String.valueOf(gray.get(300, 400)[0]);
    String pixval1 = String.valueOf(gray.get(300, 400+width/2)[0]);
    Log.d(TAG, pixvalue);
    Log.d(TAG, pixval1);
        // to do the camera image split processing using "data"
}
};

The Image that you get from the camera is in YUV420s mode and I was initially having problems accessing the data as I had created a 4 channel Mat. Actually, it needs only 1 channel Mat.