def perform_sampling(self):
if not self.prepared:
self.prepare_sampling()
# performing a conforming Delaunay triangulation using Triangle
self.tw = TriangleWrapper(self.polygon)
# self.tw.toggle_verbosity()
self.tw.apply_triangle()
# creating skeleton line from triangulation
self.skel = self.create_skeleton_line()
self.convert_skeleton_to_sample_points()
def perform_sampling(self):
from triangle_wrapper import TriangleWrapper
self.tw = TriangleWrapper()
self.skel = LineString()
for src in self.src:
self.tw.set_polygon(src)
self.tw.create_poly_data()
tmp_name = self.tw.write_poly_file()
self.tw.build_triangle_cmd(tmp_name)
self.tw.execute_triangle()
self.tw.read_node_file()
self.tw.read_ele_file()
single_skel = self.tw.create_skeleton_line()
self.skel = self.skel.union(single_skel)
#print self.skel
self.tw.cleanup()
self.convert_skeleton_to_sample_points()
def perform_sampling(self):
if not self.prepared:
self.prepare_sampling()
# performing a conforming Delaunay triangulation using Triangle
self.tw = TriangleWrapper(self.polygon)
#self.tw.toggle_verbosity()
self.tw.apply_triangle()
# creating skeleton line from triangulation
self.skel = self.create_skeleton_line()
self.convert_skeleton_to_sample_points()
def perform_sampling(self):
from triangle_wrapper import TriangleWrapper
self.tw = TriangleWrapper()
self.skel = LineString()
for src in self.src:
self.tw.set_polygon(src)
self.tw.create_poly_data()
tmp_name = self.tw.write_poly_file()
self.tw.build_triangle_cmd(tmp_name)
self.tw.execute_triangle()
self.tw.read_node_file()
self.tw.read_ele_file()
single_skel = self.tw.create_skeleton_line()
self.skel = self.skel.union(single_skel)
#print self.skel
self.tw.cleanup()
self.convert_skeleton_to_sample_points()
class SkeletonLineSampler(PolygonToPointSampler):
SIMPLIFY_TOLERANCE = 20
def __init__(self,
polygon='',
simplify=True,
simplify_tolerance=SIMPLIFY_TOLERANCE):
super(self.__class__, self).__init__(polygon)
self.simplify = simplify
self.simplify_tolerance = simplify_tolerance
def perform_sampling(self):
from triangle_wrapper import TriangleWrapper
self.tw = TriangleWrapper()
self.skel = LineString()
for src in self.src:
self.tw.set_polygon(src)
self.tw.create_poly_data()
tmp_name = self.tw.write_poly_file()
self.tw.build_triangle_cmd(tmp_name)
self.tw.execute_triangle()
self.tw.read_node_file()
self.tw.read_ele_file()
single_skel = self.tw.create_skeleton_line()
self.skel = self.skel.union(single_skel)
#print self.skel
self.tw.cleanup()
self.convert_skeleton_to_sample_points()
def convert_skeleton_to_sample_points(self):
# converting straight skeleton line to its vertices
lines = list()
if hasattr(self.skel, 'geoms'):
for line in self.skel:
lines.append(line)
else:
lines.append(self.skel)
for line in lines:
for x, y in line.coords:
sp = Point((x, y))
self.samples.append(sp)
print sp
def distance(self, from_pt, to_pt):
return sqrt((from_pt[0] - to_pt[0])**2 + (from_pt[1] - to_pt[1])**2)
class SkeletonLineSampler(PolygonPointSampler):
SIMPLIFY_TOLERANCE = 20
def __init__(
self,
polygon='',
simplify=True,
simplify_tolerance=SIMPLIFY_TOLERANCE
):
super(self.__class__, self).__init__(polygon)
self.simplify = simplify
self.simplify_tolerance = simplify_tolerance
def perform_sampling(self):
if not self.prepared:
self.prepare_sampling()
# performing a conforming Delaunay triangulation using Triangle
self.tw = TriangleWrapper(self.polygon)
# self.tw.toggle_verbosity()
self.tw.apply_triangle()
# creating skeleton line from triangulation
self.skel = self.create_skeleton_line()
self.convert_skeleton_to_sample_points()
def create_skeleton_line(self, simplify=True, simplify_tolerance=''):
"""
Create a skeleton line of the polygon by using the circumcenters of the
triangles created by the Conforming Delaunay Triangulation applied by
Triangle
Optionally simplify (by default) the skeleton by using an algorithm
provided by Shapely.
"""
self.circumcenters = list()
for t in self.tw.triangles:
self.circumcenters.append(self.calculate_circumcenter(t))
# list of skeleton segments
skel_segments = list()
for key in sorted(self.tw.shared_edges.keys()):
if self.tw.shared_edges[key] != 2:
continue
# retrieve endpoints of the skeleton segment
from_pt = self.circumcenters[key[0] - 1]
to_pt = self.circumcenters[key[1] - 1]
# creating skeleton segment
skel_segment = LineString(
[(cc.x, cc.y) for cc in (from_pt, to_pt)])
skel_segments.append(skel_segment)
else:
# merging all skeleton segments to a single (possibly multiline)
# object
skel_line = linemerge(skel_segments)
# simplifying skeleton line
if simplify:
if not simplify_tolerance:
simplify_tolerance = self.SIMPLIFY_TOLERANCE
skel_line = skel_line.simplify(simplify_tolerance, False)
return skel_line
def convert_skeleton_to_sample_points(self):
"""
Convert a straight skeleton line to its vertices.
"""
# converting straight skeleton line to its vertices
lines = list()
if hasattr(self.skel, 'geoms'):
for line in self.skel:
lines.append(line)
else:
lines.append(self.skel)
for line in lines:
for x, y in line.coords:
sp = Point((x, y))
self.samples.append(sp)
def calculate_circumcenter(self, triangle):
u"""
Calculate circumcenter of given triangle in cartesian coordinates
according to formula given by: http://is.gd/ctPx80
"""
a, b, c = [Point(triangle.exterior.coords[i]) for i in [0, 1, 2]]
d = 2 * (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))
cx = (
(a.y**2 + a.x**2) * (b.y - c.y) +
(b.y**2 + b.x**2) * (c.y - a.y) +
(c.y**2 + c.x**2) * (a.y - b.y)) / d
cy = (
(a.y**2 + a.x**2) * (c.x - b.x) +
(b.y**2 + b.x**2) * (a.x - c.x) +
(c.y**2 + c.x**2) * (b.x - a.x)) / d
return Point((cx, cy))
class SkeletonLineSampler(PolygonPointSampler):
SIMPLIFY_TOLERANCE = 20
def __init__(self, polygon = '', simplify = True, simplify_tolerance = SIMPLIFY_TOLERANCE):
super(self.__class__, self).__init__(polygon)
self.simplify = simplify
self.simplify_tolerance = simplify_tolerance
def perform_sampling(self):
if not self.prepared:
self.prepare_sampling()
# performing a conforming Delaunay triangulation using Triangle
self.tw = TriangleWrapper(self.polygon)
#self.tw.toggle_verbosity()
self.tw.apply_triangle()
# creating skeleton line from triangulation
self.skel = self.create_skeleton_line()
self.convert_skeleton_to_sample_points()
def create_skeleton_line(self, simplify = True, simplify_tolerance = ''):
u"""
Create a skeleton line of the polygon by using the circumcenters of the
triangles created by the Conforming Delaunay Triangulation applied by
Triangle
Optionally simplify (by default) the skeleton by using an algorithm
provided by Shapely.
"""
self.circumcenters = list()
for t in self.tw.triangles:
self.circumcenters.append(self.calculate_circumcenter(t))
# list of skeleton segments
skel_segments = list()
for key in sorted(self.tw.shared_edges.iterkeys()):
if self.tw.shared_edges[key] != 2:
continue
# retrieve endpoints of the skeleton segment
from_pt = self.circumcenters[key[0] - 1]
to_pt = self.circumcenters[key[1] - 1]
# creating skeleton segment
skel_segment = LineString([(cc.x, cc.y) for cc in (from_pt, to_pt)])
skel_segments.append(skel_segment)
else:
# merging all skeleton segments to a single (possibly multiline)
# object
skel_line = linemerge(skel_segments)
# simplifying skeleton line
if simplify:
if not simplify_tolerance:
simplify_tolerance = self.SIMPLIFY_TOLERANCE
skel_line = skel_line.simplify(simplify_tolerance, False)
return skel_line
def convert_skeleton_to_sample_points(self):
u"""
Convert a straight skeleton line to its vertices.
"""
# converting straight skeleton line to its vertices
lines = list()
if hasattr(self.skel, 'geoms'):
for line in self.skel:
lines.append(line)
else:
lines.append(self.skel)
for line in lines:
for x, y in line.coords:
sp = Point((x, y))
self.samples.append(sp)
def calculate_circumcenter(self, triangle):
u"""
Calculate circumcenter of given triangle in cartesian coordinates
according to formula given by: http://is.gd/ctPx80
"""
a, b, c = [Point(triangle.exterior.coords[i]) for i in [0, 1, 2]]
d = 2 * (a.x * (b.y - c.y) + b.x * (c.y - a.y) + c.x * (a.y - b.y))
cx = ((a.y**2 + a.x**2) * (b.y - c.y) + (b.y**2 + b.x**2) * (c.y - a.y) + (c.y**2 + c.x**2) * (a.y - b.y)) / d
cy = ((a.y**2 + a.x**2) * (c.x - b.x) + (b.y**2 + b.x**2) * (a.x - c.x) + (c.y**2 + c.x**2) * (b.x - a.x)) / d
return Point((cx, cy))
class SkeletonLineSampler(PolygonToPointSampler):
SIMPLIFY_TOLERANCE = 20
def __init__(self, polygon = '', simplify = True, simplify_tolerance = SIMPLIFY_TOLERANCE):
super(self.__class__, self).__init__(polygon)
self.simplify = simplify
self.simplify_tolerance = simplify_tolerance
def perform_sampling(self):
from triangle_wrapper import TriangleWrapper
self.tw = TriangleWrapper()
self.skel = LineString()
for src in self.src:
self.tw.set_polygon(src)
self.tw.create_poly_data()
tmp_name = self.tw.write_poly_file()
self.tw.build_triangle_cmd(tmp_name)
self.tw.execute_triangle()
self.tw.read_node_file()
self.tw.read_ele_file()
single_skel = self.tw.create_skeleton_line()
self.skel = self.skel.union(single_skel)
#print self.skel
self.tw.cleanup()
self.convert_skeleton_to_sample_points()
def convert_skeleton_to_sample_points(self):
# converting straight skeleton line to its vertices
lines = list()
if hasattr(self.skel, 'geoms'):
for line in self.skel:
lines.append(line)
else:
lines.append(self.skel)
for line in lines:
for x, y in line.coords:
sp = Point((x, y))
self.samples.append(sp)
print sp
def distance(self, from_pt, to_pt):
return sqrt((from_pt[0] - to_pt[0]) ** 2 + (from_pt[1] - to_pt[1]) ** 2)
