/// <summary>
/// Gets the marker identifier.
/// </summary>
/// <returns>The marker identifier.</returns>
/// <param name="markerImage">Marker image.</param>
/// <param name="nRotations">N rotations.</param>
public static int getMarkerId(Mat markerImage, MatOfInt nRotations, byte[,] markerDesign)
{
Mat grey = markerImage;
// Threshold image
Imgproc.threshold(grey, grey, 125, 255, Imgproc.THRESH_BINARY | Imgproc.THRESH_OTSU);
//Markers are divided in 7x7 regions, of which the inner 5x5 belongs to marker info
//the external border should be entirely black
int size = markerDesign.GetLength(0);
int cellSize = markerImage.rows() / (size + 2);
for (int y = 0; y < (size + 2); y++)
{
int inc = size + 1;
if (y == 0 || y == (size + 1))
{
inc = 1; //for first and last row, check the whole border
}
for (int x = 0; x < (size + 2); x += inc)
{
int cellX = x * cellSize;
int cellY = y * cellSize;
Mat cell = new Mat(grey, new OpenCVForUnity.CoreModule.Rect(cellX, cellY, cellSize, cellSize));
int nZ = Core.countNonZero(cell);
cell.Dispose();
if (nZ > (cellSize * cellSize) / 2)
{
return(-1);//can not be a marker because the border element is not black!
}
}
}
Mat bitMatrix = Mat.zeros(size, size, CvType.CV_8UC1);
//get information(for each inner square, determine if it is black or white)
for (int y = 0; y < size; y++)
{
for (int x = 0; x < size; x++)
{
int cellX = (x + 1) * cellSize;
int cellY = (y + 1) * cellSize;
Mat cell = new Mat(grey, new OpenCVForUnity.CoreModule.Rect(cellX, cellY, cellSize, cellSize));
int nZ = Core.countNonZero(cell);
if (nZ > (cellSize * cellSize) / 2)
{
bitMatrix.put(y, x, new byte[] { 1 });
}
cell.Dispose();
}
}
//check all possible rotations
Mat[] rotations = new Mat[4];
for (int i = 0; i < rotations.Length; i++)
{
rotations[i] = new Mat();
}
int[] distances = new int[4];
rotations[0] = bitMatrix;
distances[0] = hammDistMarker(rotations[0], markerDesign);
int first = distances[0];
int second = 0;
for (int i = 1; i < 4; i++)
{
//get the hamming distance to the nearest possible word
rotations[i] = rotate(rotations[i - 1]);
distances[i] = hammDistMarker(rotations[i], markerDesign);
if (distances[i] < first)
{
first = distances[i];
second = i;
}
}
nRotations.fromArray(second);
if (first == 0)
{
int id = mat2id(rotations[second]);
bitMatrix.Dispose();
for (int i = 0; i < rotations.Length; i++)
{
rotations[i].Dispose();
}
return(id);
}
return(-1);
}
/// <summary>
/// Gets the marker identifier.
/// </summary>
/// <returns>The marker identifier.</returns>
/// <param name="markerImage">Marker image.</param>
/// <param name="nRotations">N rotations.</param>
public static int getMarkerId (Mat markerImage, MatOfInt nRotations, byte[,] markerDesign)
{
Mat grey = markerImage;
// Threshold image
Imgproc.threshold (grey, grey, 125, 255, Imgproc.THRESH_BINARY | Imgproc.THRESH_OTSU);
//Markers are divided in 7x7 regions, of which the inner 5x5 belongs to marker info
//the external border should be entirely black
int size = markerDesign.GetLength(0);
int cellSize = markerImage.rows () / (size + 2);
for (int y=0; y<(size+2); y++) {
int inc = size + 1;
if (y == 0 || y == (size + 1))
inc = 1; //for first and last row, check the whole border
for (int x=0; x<(size+2); x+=inc) {
int cellX = x * cellSize;
int cellY = y * cellSize;
Mat cell = new Mat (grey, new OpenCVForUnity.Rect (cellX, cellY, cellSize, cellSize));
int nZ = Core.countNonZero (cell);
cell.Dispose ();
if (nZ > (cellSize * cellSize) / 2) {
return -1;//can not be a marker because the border element is not black!
}
}
}
Mat bitMatrix = Mat.zeros (size, size, CvType.CV_8UC1);
//get information(for each inner square, determine if it is black or white)
for (int y=0; y<size; y++) {
for (int x=0; x<size; x++) {
int cellX = (x + 1) * cellSize;
int cellY = (y + 1) * cellSize;
Mat cell = new Mat (grey, new OpenCVForUnity.Rect (cellX, cellY, cellSize, cellSize));
int nZ = Core.countNonZero (cell);
if (nZ > (cellSize * cellSize) / 2)
bitMatrix.put (y, x, new byte[]{1});
//bitMatrix.at<uchar> (y, x) = 1;
cell.Dispose ();
}
}
// Debug.Log ("bitMatrix " + bitMatrix.dump());
//check all possible rotations
Mat[] rotations = new Mat[4];
for (int i = 0; i < rotations.Length; i++) {
rotations [i] = new Mat ();
}
int[] distances = new int[4];
rotations [0] = bitMatrix;
distances [0] = hammDistMarker (rotations [0], markerDesign);
int first = distances [0];
int second = 0;
for (int i=1; i<4; i++) {
//get the hamming distance to the nearest possible word
rotations [i] = rotate (rotations [i - 1]);
distances [i] = hammDistMarker (rotations [i], markerDesign);
if (distances [i] < first) {
first = distances [i];
second = i;
}
}
// Debug.Log ("first " + first);
nRotations.fromArray (second);
if (first == 0) {
int id = mat2id (rotations [second]);
bitMatrix.Dispose ();
for (int i = 0; i < rotations.Length; i++) {
rotations [i].Dispose ();
}
return id;
}
return -1;
}