# [OpenCV4Android] Imgproc.getRectSubPix() giving errors. [closed]

Hello, I work on a thesis and for 3 days consecutive i'm held back by an error in my code that , for the love of god, can't seem to fix it.

The ideea is simple, i have a map with 3 black corners(exactly like the QR code). I get the 3 black corners center coordinates and the last point's coordinate(Point D) I want to exctract this area to a file in a way to have the map always pointed at an agnle of 0, 90, 180, 270,360 degrees. I've searched the internet and found a solution involving RotatedRectangle. Here's some code that works :

public static RotatedRect getRotatedRect(List<Point> orderedPointList, Point D){// here i have as parameters Points(in this order) Top Right and Bottom + the final calculated point(Point D);
if(orderedPointList==null)
return null;
RotatedRect rect = new RotatedRect();
Point Top = orderedPointList.get(0);
Point Right = orderedPointList.get(1);
Point Bottom = orderedPointList.get(2);
Point[] points= new Point[]{Top,Right,D,Bottom};
rect.points(points);
Point Center = new Point();
Center.x=(Bottom.x+Right.x)/2;
Center.y=(Bottom.y+Right.y)/2;
rect.center = Center;
double diference1=Top.x-Bottom.x;
double difference2=Top.y-Bottom.y;
double angle=Math.atan(diference1-difference2) * 180/Math.PI;// this formula is used to see how much the map is rotated untill now i haven't tested it for all degrees but as i see it returns -180 0 180.
rect.angle=angle;
double mapwidth=Math.sqrt((Right.x-Top.x)*(Right.x-Top.x)+(Right.y-Top.y)*(Right.y-Top.y));
double mapheight=Math.sqrt((Bottom.x-Top.x)*(Bottom.x-Top.x)+(Bottom.y-Top.y)*(Bottom.y-Top.y));
rect.size.width=mapwidth;
rect.size.height=mapheight; // here i set the RotatedRectangle width and height.
return rect;
}


The following code, however doesn't work no matter what i do:

public static Mat getRotatedRectMat(Mat mImage,RotatedRect rect){
if(rect==null)
return null;
Mat M  = new Mat();
Mat rotated = new Mat();
Mat clone=mImage.clone();
//clone.convertTo(clone, CvType.CV_32F);
//rotated.convertTo(rotated, CvType.CV_32F);
// perform the affine transformation
Rect boundingRect = rect.boundingRect();
if(boundingRect.x >= 0 && boundingRect.y >=0
&& (boundingRect.x+boundingRect.width) < clone.cols() &&
(boundingRect.y+boundingRect.height) < clone.rows() ){
Mat cropped=new Mat();
M = Imgproc.getRotationMatrix2D(rect.center, rect.angle, 0.5);
Imgproc.warpAffine(clone, rotated, M, clone.size(), Imgproc.INTER_AREA);
Imgproc.getRectSubPix(rotated, rect.size, rect.center, cropped);//CRASHES exactly right here
reason:Noone knows
return cropped;

}


Some thing's i've tried from stackoverflow& other sites: http://www.tech.theplayhub.com/imgpro... http://stackoverflow.com/questions/11... - this is the closest result i'd want to get but i have no ideea how to do it in OpenCV4Android

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