Fix Douglas-Peucker algorithm

scanaerial.py

@@ -228,10 +228,9 @@
         popped = False
 
         if not config.getint('SCAN', 'deactivate_simplifying'):
+            lin.append(lin[0])
             lin = douglas_peucker(lin, DOUGLAS_PEUCKER_EPSILON)
-            if len(lin) >= 2:
-                if lin[len(lin) - 1] == lin[len(lin) - 2]:
-                    lin.pop()
+            lin.pop()
             debug("line found; simplified to %s" % len(lin))
         else:
             debug("skipped simplifing")
@@ -242,10 +241,9 @@
 
 if lin:
     if not config.getint('SCAN', 'deactivate_simplifying'):
+        lin.append(lin[0])
         lin = douglas_peucker(lin, DOUGLAS_PEUCKER_EPSILON)
-        if len(lin) >= 2:
-            if lin[len(lin) - 1] == lin[len(lin) - 2]:
-                lin.pop()
+        lin.pop()
         debug("line post-found; simplified to %s" % len(lin))
     else:
         debug("skipped simplifing")

scanaerial_functions.py

@@ -40,8 +40,8 @@ def point_line_distance(point, startline, endline):
     """
 
     if (startline == endline):
-        return ((startline[0] - endline[0]) ** 2 + \
-                 (startline[1] - endline[1]) ** 2) ** 0.5
+        return ((startline[0] - point[0]) ** 2 + \
+                 (startline[1] - point[1]) ** 2) ** 0.5
     else:
         return abs((endline[0] - startline[0]) * (startline[1] - point[1]) - \
                      (startline[0] - point[0]) * (endline[1] - startline[1])) / \
@@ -67,7 +67,7 @@ def douglas_peucker(nodes, epsilon):
 
     if farthest_dist > epsilon:
         seg_a = douglas_peucker(nodes[0:farthest_node + 1], epsilon)
-        seg_b = douglas_peucker(nodes[farthest_node:-1], epsilon)
+        seg_b = douglas_peucker(nodes[farthest_node:], epsilon)
         nodes = seg_a[:-1] + seg_b
     else:
         return [nodes[0], nodes[-1]]