import math
import geojson
class GeoJSON():
def __init__(self, v):
self.data = v.data
self.refX, self.refY = self.getMapReference()
self.startX, self.startY = self.getStartReference()
self.refLat, self.refLng = self.getRefLat()
self.geojson = self.createGeoJSON()
def getMapReference(self):
""" Retrieve reference map coordinates from Vissim parameters
Input: None
Output: x, y coordinates
"""
x = float(self.data.xpath('./netPara/refPointMap')[0].attrib['x'])
y = float(self.data.xpath('./netPara/refPointMap')[0].attrib['y'])
return x, y
def getStartReference(self):
""" Retrieve reference start coordinates from Vissim parameters
Input: None
Output: x, y coordinates
"""
x = float(self.data.xpath('./netPara/refPointNet')[0].attrib['x'])
y = float(self.data.xpath('./netPara/refPointNet')[0].attrib['y'])
return x, y
def metersToLatLng(self, x, y):
""" Convert xy points to latlng.
Input: x, y
Output: WGS84 lat/lng
"""
extent = 20015085 # height/width in meters of the VISSIM map
lng = x * 180 / float(extent)
y = y * 180 / float(extent)
lat = math.atan(math.exp(y*(math.pi/180.0))) * (360 / math.pi) - 90
return lat, lng
def getRefLat(self):
refLat, refLng = self.metersToLatLng(self.refX, self.refY)
return refLat, refLng
def scaledMetersToNode(self, xy):
""" Remove Mercator scaling factor and reference point.
Input: scaled xy
Output: latlng node
"""
scaleX, scaleY = xy
scaleX, scaleY = float(scaleX), float(scaleY)
scale = 1 / math.cos(math.radians(self.refLat))
x = (scaleX * scale) + self.refX - self.startX
y = (scaleY * scale) + self.refY - self.startY
lat, lng = self.metersToLatLng(x, y)
return lat, lng
def createGeoJSON(self):
""" Get list of link geometries and properties to be converted.
Input: Vissim object
Output: list of links
"""
features = []
for link in self.data.xpath('./links/link'):
geos = []
linkNum = link.attrib['no']
for geo in link.xpath('./geometry/points3D/point3D'):
x, y = geo.attrib['x'], geo.attrib['y']
latLng = self.scaledMetersToNode((x, y))
geos.append(latLng)
linkNum = link.attrib['no']
laneNum = str(len(link.xpath('./lanes/lane')))
multiLine = geojson.MultiLineString(coordinates=geos)
features.append(geojson.Feature(id=linkNum, geometry=multiLine,
properties={'lane': laneNum,
'id': linkNum}))
return geojson.FeatureCollection(features)
def export(self, filename):
""" Export GeoJSON object to file
Input: filename
Output: written file
"""
f = open(filename, 'w')
f.writelines(geojson.dumps(self.geojson))
f.close()
