void
pcl::pcl_2d::edge::canny (ImageType &output, ImageType &input)
{
float tHigh = 50;
float tLow = 20;
const int height = input.size();
const int width = input[0].size();
/*noise reduction using gaussian blurring*/
ImageType gaussian_kernel;
conv_2d->gaussianKernel (5, 1.4, gaussian_kernel);
conv_2d->convolve (output, gaussian_kernel, input);
/*edge detection usign Sobel*/
ImageType G;
ImageType thet;
sobelMagnitudeDirection (G, thet, input);
/*edge discretization*/
float angle;
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
angle = (thet[i][j] / 3.14f) * 180;
if (((angle < 22.5) && (angle > -22.5)) || (angle > 157.5) || (angle < -157.5))
thet[i][j] = 0;
else
if (((angle > 22.5) && (angle < 67.5)) || ((angle < -112.5) && (angle > -157.5)))
thet[i][j] = 45;
else
if (((angle > 67.5) && (angle < 112.5)) || ((angle < -67.5) && (angle > -112.5)))
thet[i][j] = 90;
else
if (((angle > 112.5) && (angle < 157.5)) || ((angle < -22.5) && (angle > -67.5)))
thet[i][j] = 135;
}
}
float max;
/*tHigh and non-maximal supression*/
for (int i = 1; i < height - 1; i++)
{
for (int j = 1; j < width - 1; j++)
{
if (G[i][j] < tHigh)
continue;
max = G[i][j];
switch ((int)thet[i][j])
{
case 0:
if(G[i][j] < G[i][j-1] || G[i][j] < G[i][j+1])
G[i][j] = 0;
break;
case 45:
if(G[i][j] < G[i-1][j+1] || G[i][j] < G[i+1][j-1])
G[i][j] = 0;
break;
case 90:
if(G[i][j] < G[i-1][j] || G[i][j] < G[i+1][j])
G[i][j] = 0;
break;
case 135:
if(G[i][j] < G[i-1][j-1] || G[i][j] < G[i+1][j+1])
G[i][j] = 0;
break;
}
}
}
/*edge tracing*/
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
if (G[i][j] < tHigh)
continue;
switch ((int)thet[i][j])
{
case 0:
cannyTraceEdge (1, 0, i, j, 0, tLow, tHigh, G, thet);
cannyTraceEdge (-1, 0, i, j, 0, tLow, tHigh, G, thet);
break;
case 45:
cannyTraceEdge (1, 1, i, j, 45, tLow, tHigh, G, thet);
cannyTraceEdge (-1, -1, i, j, 45, tLow, tHigh, G, thet);
break;
case 90:
cannyTraceEdge (0, -1, i, j, 90, tLow, tHigh, G, thet);
cannyTraceEdge (0, 1, i, j, 90, tLow, tHigh, G, thet);
break;
case 135:
cannyTraceEdge (-1, 1, i, j, 135, tLow, tHigh, G, thet);
cannyTraceEdge (1, -1, i, j, 135, tLow, tHigh, G, thet);
break;
}
}
}
/*final thresholding*/
output.resize (height);
for (int i = 0; i < height; i++)
{
output[i].resize (width);
for (int j = 0; j < width; j++)
{
if (G[i][j] < tHigh)
output[i][j] = 0;
else
output[i][j] = 255;
}
}
}
template <typename PointInT, typename PointOutT> void
pcl_1_8::Edge<PointInT, PointOutT>::canny (
const pcl::PointCloud<PointInT> &input_x,
const pcl::PointCloud<PointInT> &input_y,
pcl::PointCloud<PointOutT> &output)
{
float tHigh = hysteresis_threshold_high_;
float tLow = hysteresis_threshold_low_;
const int height = input_x.height;
const int width = input_x.width;
output.resize (height * width);
output.height = height;
output.width = width;
// Noise reduction using gaussian blurring
pcl::PointCloud<pcl::PointXYZI>::Ptr gaussian_kernel (new pcl::PointCloud<pcl::PointXYZI>);
kernel_.setKernelSize (3);
kernel_.setKernelSigma (1.0);
kernel_.setKernelType (kernel<pcl::PointXYZI>::GAUSSIAN);
kernel_.fetchKernel (*gaussian_kernel);
convolution_.setKernel (*gaussian_kernel);
PointCloudIn smoothed_cloud_x;
convolution_.setInputCloud (input_x.makeShared());
convolution_.filter (smoothed_cloud_x);
PointCloudIn smoothed_cloud_y;
convolution_.setInputCloud (input_y.makeShared());
convolution_.filter (smoothed_cloud_y);
// Edge detection usign Sobel
pcl::PointCloud<PointXYZIEdge>::Ptr edges (new pcl::PointCloud<PointXYZIEdge>);
sobelMagnitudeDirection (smoothed_cloud_x, smoothed_cloud_y, *edges.get ());
// Edge discretization
discretizeAngles (*edges);
pcl::PointCloud<pcl::PointXYZI>::Ptr maxima (new pcl::PointCloud<pcl::PointXYZI>);
suppressNonMaxima (*edges, *maxima, tLow);
// Edge tracing
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
if ((*maxima)(j, i).intensity < tHigh || (*maxima)(j, i).intensity == std::numeric_limits<float>::max ())
continue;
(*maxima)(j, i).intensity = std::numeric_limits<float>::max ();
cannyTraceEdge ( 1, 0, i, j, *maxima);
cannyTraceEdge (-1, 0, i, j, *maxima);
cannyTraceEdge ( 1, 1, i, j, *maxima);
cannyTraceEdge (-1, -1, i, j, *maxima);
cannyTraceEdge ( 0, -1, i, j, *maxima);
cannyTraceEdge ( 0, 1, i, j, *maxima);
cannyTraceEdge (-1, 1, i, j, *maxima);
cannyTraceEdge ( 1, -1, i, j, *maxima);
}
}
// Final thresholding
for (int i = 0; i < height; i++)
{
for (int j = 0; j < width; j++)
{
if ((*maxima)(j, i).intensity == std::numeric_limits<float>::max ())
output (j, i).magnitude = 255;
else
output (j, i).magnitude = 0;
}
}
}