Delaunay Triangulation & Voronoi Diagrams

Delaunay/delaunay.cpp

@@ -0,0 +1,145 @@
+#include <opencv2/imgproc/imgproc.hpp>
+#include <opencv2/highgui/highgui.hpp>
+#include <iostream>
+#include <fstream>
+
+using namespace cv;
+using namespace std;
+
+// Draw a single point
+static void draw_point( Mat& img, Point2f fp, Scalar color )
+{
+    circle( img, fp, 2, color, CV_FILLED, CV_AA, 0 );
+}
+
+// Draw delaunay triangles
+static void draw_delaunay( Mat& img, Subdiv2D& subdiv, Scalar delaunay_color )
+{
+
+    vector<Vec6f> triangleList;
+    subdiv.getTriangleList(triangleList);
+    vector<Point> pt(3);
+    Size size = img.size();
+    Rect rect(0,0, size.width, size.height);
+
+    for( size_t i = 0; i < triangleList.size(); i++ )
+    {
+        Vec6f t = triangleList[i];
+        pt[0] = Point(cvRound(t[0]), cvRound(t[1]));
+        pt[1] = Point(cvRound(t[2]), cvRound(t[3]));
+        pt[2] = Point(cvRound(t[4]), cvRound(t[5]));
+
+        // Draw rectangles completely inside the image.
+        if ( rect.contains(pt[0]) && rect.contains(pt[1]) && rect.contains(pt[2]))
+        {
+            line(img, pt[0], pt[1], delaunay_color, 1, CV_AA, 0);
+            line(img, pt[1], pt[2], delaunay_color, 1, CV_AA, 0);
+            line(img, pt[2], pt[0], delaunay_color, 1, CV_AA, 0);
+        }
+    }
+}
+
+//Draw voronoi diagrams
+static void draw_voronoi( Mat& img, Subdiv2D& subdiv )
+{
+    vector<vector<Point2f> > facets;
+    vector<Point2f> centers;
+    subdiv.getVoronoiFacetList(vector<int>(), facets, centers);
+
+    vector<Point> ifacet;
+    vector<vector<Point> > ifacets(1);
+
+    for( size_t i = 0; i < facets.size(); i++ )
+    {
+        ifacet.resize(facets[i].size());
+        for( size_t j = 0; j < facets[i].size(); j++ )
+            ifacet[j] = facets[i][j];
+
+        Scalar color;
+        color[0] = rand() & 255;
+        color[1] = rand() & 255;
+        color[2] = rand() & 255;
+        fillConvexPoly(img, ifacet, color, 8, 0);
+
+        ifacets[0] = ifacet;
+        polylines(img, ifacets, true, Scalar(), 1, CV_AA, 0);
+        circle(img, centers[i], 3, Scalar(), CV_FILLED, CV_AA, 0);
+    }
+}
+
+
+int main( int argc, char** argv)
+{
+
+    // Define window names
+    string win_delaunay = "Delaunay Triangulation";
+    string win_voronoi = "Voronoi Diagram";
+
+    // Turn on animation while drawing triangles
+    bool animate = true;
+
+    // Define colors for drawing.
+    Scalar delaunay_color(255,255,255), points_color(0, 0, 255);
+
+    // Read in the image.
+    Mat img = imread("obama.jpg");
+
+    // Keep a copy around
+    Mat img_orig = img.clone();
+
+    // Rectangle to be used with Subdiv2D
+    Size size = img.size();
+    Rect rect(0, 0, size.width, size.height);
+
+    // Create an instance of Subdiv2D
+    Subdiv2D subdiv(rect);
+
+    // Create a vector of points.
+    vector<Point2f> points;
+
+    // Read in the points from a text file
+    ifstream ifs("obama.txt");
+    int x, y;
+    while(ifs >> x >> y)
+    {
+        points.push_back(Point2f(x,y));
+    }
+
+    // Insert points into subdiv
+    for( vector<Point2f>::iterator it = points.begin(); it != points.end(); it++)
+    {
+        subdiv.insert(*it);
+        // Show animation
+        if (animate)
+        {
+            Mat img_copy = img_orig.clone();
+            // Draw delaunay triangles
+            draw_delaunay( img_copy, subdiv, delaunay_color );
+            imshow(win_delaunay, img_copy);
+            waitKey(100);
+        }
+
+    }
+
+    // Draw delaunay triangles
+    draw_delaunay( img, subdiv, delaunay_color );
+
+    // Draw points
+    for( vector<Point2f>::iterator it = points.begin(); it != points.end(); it++)
+    {
+        draw_point(img, *it, points_color);
+    }
+
+    // Allocate space for voronoi Diagram
+    Mat img_voronoi = Mat::zeros(img.rows, img.cols, CV_8UC3);
+
+    // Draw voronoi diagram
+    draw_voronoi( img_voronoi, subdiv );
+
+    // Show results.
+    imshow( win_delaunay, img);
+    imshow( win_voronoi, img_voronoi);
+    waitKey(0);
+
+    return 0;
+}

Delaunay/delaunay.py

@@ -0,0 +1,131 @@
+#!/usr/bin/python
+
+import cv2
+import numpy as np
+import random
+
+# Check if a point is inside a rectangle
+def rect_contains(rect, point) :
+    if point[0] < rect[0] :
+        return False
+    elif point[1] < rect[1] :
+        return False
+    elif point[0] > rect[2] :
+        return False
+    elif point[1] > rect[3] :
+        return False
+    return True
+
+# Draw a point
+def draw_point(img, p, color ) :
+    cv2.circle( img, p, 2, color, cv2.cv.CV_FILLED, cv2.CV_AA, 0 )
+
+
+# Draw delaunay triangles
+def draw_delaunay(img, subdiv, delaunay_color ) :
+
+    triangleList = subdiv.getTriangleList();
+    size = img.shape
+    r = (0, 0, size[1], size[0])
+
+    for t in triangleList :
+
+        pt1 = (t[0], t[1])
+        pt2 = (t[2], t[3])
+        pt3 = (t[4], t[5])
+
+        if rect_contains(r, pt1) and rect_contains(r, pt2) and rect_contains(r, pt3) :
+
+            cv2.line(img, pt1, pt2, delaunay_color, 1, cv2.CV_AA, 0)
+            cv2.line(img, pt2, pt3, delaunay_color, 1, cv2.CV_AA, 0)
+            cv2.line(img, pt3, pt1, delaunay_color, 1, cv2.CV_AA, 0)
+
+
+# Draw voronoi diagram
+def draw_voronoi(img, subdiv) :
+
+    ( facets, centers) = subdiv.getVoronoiFacetList([])
+
+    for i in xrange(0,len(facets)) :
+        ifacet_arr = []
+        for f in facets[i] :
+            ifacet_arr.append(f)
+
+        ifacet = np.array(ifacet_arr, np.int)
+        color = (random.randint(0, 255), random.randint(0, 255), random.randint(0, 255))
+
+        cv2.fillConvexPoly(img, ifacet, color, cv2.CV_AA, 0);
+        ifacets = np.array([ifacet])
+        cv2.polylines(img, ifacets, True, (0, 0, 0), 1, cv2.CV_AA, 0)
+        cv2.circle(img, (centers[i][0], centers[i][1]), 3, (0, 0, 0), cv2.cv.CV_FILLED, cv2.CV_AA, 0)
+
+
+if __name__ == '__main__':
+
+    # Define window names
+    win_delaunay = "Delaunay Triangulation"
+    win_voronoi = "Voronoi Diagram"
+
+    # Turn on animation while drawing triangles
+    animate = True
+
+    # Define colors for drawing.
+    delaunay_color = (255,255,255)
+    points_color = (0, 0, 255)
+
+    # Read in the image.
+    img = cv2.imread("obama.jpg");
+
+    # Keep a copy around
+    img_orig = img.copy();
+
+    # Rectangle to be used with Subdiv2D
+    size = img.shape
+    rect = (0, 0, size[1], size[0])
+
+    # Create an instance of Subdiv2D
+    subdiv = cv2.Subdiv2D(rect);
+
+    # Create an array of points.
+    points = [];
+
+    # Read in the points from a text file
+    with open("obama.txt") as file :
+        for line in file :
+            x, y = line.split()
+            points.append((int(x), int(y)))
+
+    # Insert points into subdiv
+    for p in points :
+        subdiv.insert(p)
+
+        # Show animation
+        if animate :
+            img_copy = img_orig.copy()
+            # Draw delaunay triangles
+            draw_delaunay( img_copy, subdiv, (255, 255, 255) );
+            cv2.imshow(win_delaunay, img_copy)
+            cv2.waitKey(100)
+
+    # Draw delaunay triangles
+    draw_delaunay( img, subdiv, (255, 255, 255) );
+
+    # Draw points
+    for p in points :
+        draw_point(img, p, (0,0,255))
+
+    # Allocate space for voronoi Diagram
+    img_voronoi = np.zeros(img.shape, dtype = img.dtype)
+
+    # Draw voronoi diagram
+    draw_voronoi(img_voronoi,subdiv)
+
+    # Show results
+    cv2.imshow(win_delaunay,img)
+    cv2.imshow(win_voronoi,img_voronoi)
+    cv2.waitKey(0)
+
+
+
+
+

Delaunay/obama.txt

@@ -0,0 +1,68 @@
+207 242
+210 269
+214 297
+220 322
+229 349
+243 373
+261 394
+282 412
+308 416
+334 408
+356 388
+374 367
+388 344
+397 319
+403 291
+405 263
+408 235
+221 241
+232 225
+250 219
+270 219
+289 223
+320 222
+339 216
+358 215
+375 220
+387 233
+304 240
+304 259
+304 277
+304 296
+281 311
+292 312
+303 314
+315 310
+326 307
+243 247
+254 240
+266 239
+276 245
+266 247
+254 249
+332 243
+343 236
+356 236
+367 242
+356 245
+344 245
+263 346
+278 341
+293 336
+303 340
+315 335
+331 338
+348 342
+332 353
+318 360
+305 362
+294 361
+279 356
+270 347
+293 347
+304 348
+316 345
+342 343
+316 345
+304 348
+294 347