本文介绍了当我尝试在Android-NDK上使用getPerspectiveTransform转换透视图图像时，声明失败的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
所以我试图在ndk上使用opencv在android上检测一个正方形对象，并将其裁剪为2D图，我检测到正方形的点，但是当我尝试使用getPerspectiveTRansform(src，dst)时，我得到了此错误消息:
So i'm trying to detect an square object on android using opencv on ndk, and crop it to a 2D figure, I detect the points of the squares, but When i Try to use getPerspectiveTRansform(src, dst) I get this error Message:
OpenCV Error: Assertion failed (src.checkVector(2, CV_32F) == 4 && dst.checkVector(2, CV_32F) == 4) in cv::Mat cv::getPerspectiveTransform(cv::InputArray, cv::InputArray), file /home/reports/ci/slave/50-SDK/opencv/modules/imgproc/src/imgwarp.cpp, line 3607
这是我在android中的活动
This is My Activity in android:
package org.opencv.samples.tutorial1;
import java.io.ByteArrayOutputStream;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.android.Utils;
import org.opencv.core.CvException;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SurfaceView;
import android.view.View;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.Toast;
public class Tutorial1Activity extends Activity implements
CvCameraViewListener2 {
private static final String TAG = "OCVSample::Activity";
private Mat mRgba;
private Mat mGrayMat;
private Mat imageTaken;
private CameraBridgeViewBase mOpenCvCameraView;
private boolean mIsJavaCamera = true;
private MenuItem mItemSwitchCamera = null;
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS: {
Log.i(TAG, "OpenCV loaded successfully");
System.loadLibrary("native_sample");
mOpenCvCameraView.enableView();
}
break;
default: {
super.onManagerConnected(status);
}
break;
}
}
};
public Tutorial1Activity() {
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);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setContentView(R.layout.tutorial1_surface_view);
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_native_surface_view);
mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
mOpenCvCameraView.setCvCameraViewListener(this);
}
@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();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
Log.i(TAG, "called onCreateOptionsMenu");
// mItemSwitchCamera = menu.add("Toggle Native/Java camera");
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
String toastMesage = new String();
Log.i(TAG, "called onOptionsItemSelected; selected item: " + item);
if (item == mItemSwitchCamera) {
mOpenCvCameraView.setVisibility(SurfaceView.GONE);
mIsJavaCamera = !mIsJavaCamera;
if (mIsJavaCamera) {
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_java_surface_view);
toastMesage = "Java Camera";
} else {
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial1_activity_native_surface_view);
toastMesage = "Native Camera";
}
mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
mOpenCvCameraView.setCvCameraViewListener(this);
mOpenCvCameraView.enableView();
mOpenCvCameraView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
takePicture();
}
});
Toast toast = Toast.makeText(this, toastMesage, Toast.LENGTH_LONG);
toast.show();
}
return true;
}
public void takePicture() {
if (imageTaken != null) {
Bitmap resultBitmap = null;
try {
// Imgproc.cvtColor(imageTaken, imageTaken,
// Imgproc.COLOR_BGR2GRAY);
// Imgproc.cvtColor(imageTaken, imageTaken,
// Imgproc.COLOR_GRAY2RGBA, 4);
/*
* Mat test =
* Imgproc.getPerspectiveTransform(ImageSrc,ImageDst);
* Imgproc.warpPerspective(ImageSrc, ImageDst, test,
* ImageDst.size());
*/
resultBitmap = Bitmap.createBitmap(imageTaken.cols(),
imageTaken.rows(), Bitmap.Config.ARGB_8888);
//
Utils.matToBitmap(imageTaken, resultBitmap);
byte[] sendData = codec(resultBitmap,
Bitmap.CompressFormat.JPEG, 50);
Intent i = new Intent(getApplicationContext(),
ShowImageActivity.class);
i.putExtra("data", sendData);
startActivity(i);
} catch (CvException e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
private byte[] codec(Bitmap src, Bitmap.CompressFormat format, int quality) {
ByteArrayOutputStream os = new ByteArrayOutputStream();
src.compress(format, quality, os);
byte[] array = os.toByteArray();
System.out.println(array.length);
// return BitmapFactory.decodeByteArray(array, 0, array.length);
return array;
}
public void onCameraViewStarted(int width, int height) {
mRgba = new Mat();
mGrayMat = new Mat();
imageTaken = new Mat();
}
public void onCameraViewStopped() {
mRgba.release();
mGrayMat.release();
imageTaken.release();
}
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
/*long start = System.currentTimeMillis();
Size originalSize = inputFrame.rgba().size();
Imgproc.resize(inputFrame.rgba(), mRgba, new Size(800, 480));
*/
// FindSquares(inputFrame.rgba().getNativeObjAddr(), 1);
// imageTaken = inputFrame.clone();
// System.out.println(inputFrame.rgba().type());
findSquare(inputFrame.rgba().getNativeObjAddr(), imageTaken.getNativeObjAddr(), 1);
// if (mDraw == 1) {
/*Imgproc.resize(mRgba, inputFrame.rgba(), originalSize);
// }
long end = System.currentTimeMillis();
Log.d("Frame time", "" + (end - start) + " ms");
*/
return inputFrame.rgba();
}
public native void FindFeatures(long matAddrGr, long matAddrRgba);
public native int FindSquares(long matAddrRgba, int draw);
public native void findSquare(long matAddrRgba, long matAddrDescriptor, int draw);
}
这是我的jni代码:
JNIEXPORT jint JNICALL Java_com_gconsent_opencv_MainActivity_findSquare(JNIEnv*,
jobject, jlong addrRgba, jlong addrDescriptor, jlong addrSrc, jlong addrDst, jint draw){
Mat& image = *(Mat*) addrRgba;
Mat& imageCropped = *(Mat*) addrDescriptor;
Mat& imageSrc = *(Mat*) addrSrc;
Mat& imageDst = *(Mat*) addrDst;
Mat newSrc = image.clone();
imageCropped = image.clone();
Mat testImage = image.clone();
// blur will enhance edge detection
Mat blurred(testImage);
medianBlur(testImage, blurred, 9);
Mat gray0(blurred.size(), CV_8U), gray;
vector < vector<Point> > contours;
// find squares in every color plane of the image
for (int c = 0; c < 3; c++) {
int ch[] = { c, 0 };
mixChannels(&blurred, 1, &gray0, 1, ch, 1);
// try several threshold levels
const int threshold_level = 2;
for (int l = 0; l < threshold_level; l++) {
// Use Canny instead of zero threshold level!
// Canny helps to catch squares with gradient shading
if (l == 0) {
Canny(gray0, gray, 10, 20, 3); //
// Dilate helps to remove potential holes between edge segments
dilate(gray, gray, Mat(), Point(-1, -1));
} else {
gray = gray0 >= (l + 1) * 255 / threshold_level;
}
// Find contours and store them in a list
findContours(gray, contours, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
// Test contours
vector < Point > approx;
for (size_t i = 0; i < contours.size(); i++) {
// approximate contour with accuracy proportional
// to the contour perimeter
approxPolyDP(Mat(contours[i]), approx,
arcLength(Mat(contours[i]), true) * 0.02, true);
// Note: absolute value of an area is used because
// area may be positive or negative - in accordance with the
// contour orientation
if (approx.size() == 4 && fabs(contourArea(Mat(approx))) > 1000
&& isContourConvex(Mat(approx))) {
double maxCosine = 0;
for (int j = 2; j < 5; j++) {
double cosine = fabs(
angle(approx[j % 4], approx[j - 2],
approx[j - 1]));
maxCosine = MAX(maxCosine, cosine);
}
if (maxCosine < 0.3) {
line(image, approx[0], approx[1],
Scalar(0, 255, 0, 255), 2, 4, 0);
line(image, approx[1], approx[2],
Scalar(0, 255, 0, 255), 2, 4, 0);
line(image, approx[2], approx[3],
Scalar(0, 255, 0, 255), 2, 4, 0);
line(image, approx[3], approx[0],
Scalar(0, 255, 0, 255), 2, 4, 0);
vector<Point2f> src(4);
// src.push_back(approx[0]);
// src.push_back(approx[1]);
// src.push_back(approx[2]);
// src.push_back(approx[3]);
src[0] = approx[0];
src[1] = approx[1];
src[2] = approx[2];
src[3] = approx[3];
cv::Mat quad = cv::Mat::zeros(300, 220, CV_8U);
// transformed quadrangle
vector < Point2f > quad_pts(4);
// Point2f quad_pts[4];
quad_pts.push_back(Point(0, 0));
quad_pts.push_back(Point(quad.cols, 0));
quad_pts.push_back(Point(quad.cols, quad.rows));
quad_pts.push_back(Point(0, quad.rows));
// quad_pts[0] = Point(0, 0);
// quad_pts[1] = Point(quad.cols, 0);
// quad_pts[2] = Point(quad.cols, quad.rows);
// quad_pts[3] = Point(0, quad.rows);
imageSrc = Mat(src);
imageDst = Mat(quad_pts);
Mat transmtx = getPerspectiveTransform(src, quad_pts);
warpPerspective(src, quad, transmtx, quad.size());
imageCropped = quad.clone();
}
}
}
}
}
// imageCropped = getPolygon(newSrc);
return 1;
}
推荐答案
将输入cv::Mat类型更改为CV_32FC2.还可以查看此.
Change the input cv::Mat type to CV_32FC2.Also take a look at this.
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