示例#1
0
    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()
示例#2
0
    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()
示例#3
0
    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)
示例#4
0
    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)