def simplify_layers(self, layers, layerFeatures, layerOpts):
"""
performs polygon simplification
"""
# step 1: unify
from simplify import create_point_store, simplify_distance
point_store = create_point_store()
for id in layers:
if layerOpts[id]['simplify'] is not False:
for feature in layerFeatures[id]:
feature.geom.unify(point_store,
layerOpts[id]['unify-precision'])
# print 'unified points:', point_store['removed'], (100*point_store['removed']/(point_store['removed']+point_store['kept'])),'%'
to_simplify = []
for id in layers:
if layerOpts[id]['simplify'] is not False:
to_simplify.append(id)
to_simplify.sort(key=lambda id: layerOpts[id]['simplify'])
for id in to_simplify:
if self._verbose:
print 'simplifying', id
for feature in layerFeatures[id]:
for pts in feature.geom.points():
simplify_distance(pts, layerOpts[id]['simplify'])
feature.geom.update()
def simplify_layers(self, layers, layerFeatures, layerOpts):
"""
performs polygon simplification
"""
# step 1: unify
from simplify import create_point_store, simplify_distance
point_store = create_point_store()
for id in layers:
if layerOpts[id]['simplify'] is not False:
for feature in layerFeatures[id]:
feature.geom.unify(point_store, layerOpts[id]['unify-precision'])
#print 'unified points:', point_store['removed'], (100*point_store['removed']/(point_store['removed']+point_store['kept'])),'%'
to_simplify = []
for id in layers:
if layerOpts[id]['simplify'] is not False:
to_simplify.append(id)
to_simplify.sort(key=lambda id: layerOpts[id]['simplify'])
for id in to_simplify:
print 'simplifying', id
for feature in layerFeatures[id]:
for pts in feature.geom.points():
simplify_distance(pts, layerOpts[id]['simplify'])
feature.geom.update()
def _simplify_layers(self):
"""
### Simplify geometries
"""
from simplify import create_point_store, simplify_lines
# We will use a glocal point cache for all layers. If the
# same point appears in more than one layer, it will be
# simplified only once.
point_store = create_point_store()
# Compute topology for all layers. That means that every point
# is checked for duplicates, and eventually replaced with
# an existing instance.
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
feature.compute_topology(
point_store, layer.options['unify-precision'])
# Now we break features into line segments, which makes them
# easier to simplify.
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
feature.break_into_lines()
# Finally, apply the chosen line simplification algorithm.
total = 0
kept = 0
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
lines = feature.break_into_lines()
lines = simplify_lines(
lines, layer.options['simplify']['method'],
layer.options['simplify']['tolerance'])
for line in lines:
total += len(line)
for pt in line:
if not pt.deleted:
kept += 1
# ..and restore the geometries from the simplified line segments.
feature.restore_geometry(
lines, layer.options['filter-islands'])
return (total, kept)
def _simplify_layers(self):
"""
### Simplify geometries
"""
from simplify import create_point_store, simplify_lines
# We will use a glocal point cache for all layers. If the
# same point appears in more than one layer, it will be
# simplified only once.
point_store = create_point_store()
# Compute topology for all layers. That means that every point
# is checked for duplicates, and eventually replaced with
# an existing instance.
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
feature.compute_topology(point_store, layer.options['unify-precision'])
# Now we break features into line segments, which makes them
# easier to simplify.
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
feature.break_into_lines()
# Finally, apply the chosen line simplification algorithm.
total = 0
kept = 0
for layer in self.layers:
if layer.options['simplify'] is not False:
for feature in layer.features:
if feature.is_simplifyable():
lines = feature.break_into_lines()
lines = simplify_lines(lines, layer.options['simplify']['method'], layer.options['simplify']['tolerance'])
for line in lines:
total += len(line)
for pt in line:
if not pt.deleted:
kept += 1
# ..and restore the geometries from the simplified line segments.
feature.restore_geometry(lines, layer.options['filter-islands'])
return (total, kept)