/
generate_tiles.py
executable file
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/
generate_tiles.py
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#!/usr/bin/python
from math import pi,cos,sin,log,exp,atan
from subprocess import call
import sys, os
from Queue import Queue
import mapnik2 as mapnik
import threading
import json
DEG_TO_RAD = pi/180
RAD_TO_DEG = 180/pi
# Default number of rendering threads to spawn, should be roughly equal to number of CPU cores available
NUM_THREADS = 4
def minmax (a,b,c):
a = max(a,b)
a = min(a,c)
return a
class GoogleProjection:
def __init__(self,levels=18):
self.Bc = []
self.Cc = []
self.zc = []
self.Ac = []
c = 256
for d in range(0,levels):
e = c/2;
self.Bc.append(c/360.0)
self.Cc.append(c/(2 * pi))
self.zc.append((e,e))
self.Ac.append(c)
c *= 2
def fromLLtoPixel(self,ll,zoom):
d = self.zc[zoom]
e = round(d[0] + ll[0] * self.Bc[zoom])
f = minmax(sin(DEG_TO_RAD * ll[1]),-0.9999,0.9999)
g = round(d[1] + 0.5*log((1+f)/(1-f))*-self.Cc[zoom])
return (e,g)
def fromPixelToLL(self,px,zoom):
e = self.zc[zoom]
f = (px[0] - e[0])/self.Bc[zoom]
g = (px[1] - e[1])/-self.Cc[zoom]
h = RAD_TO_DEG * ( 2 * atan(exp(g)) - 0.5 * pi)
return (f,h)
class RenderThread:
def __init__(self, tile_dir, mapfile, q, printLock, maxZoom):
self.tile_dir = tile_dir
self.q = q
self.m = mapnik.Map(256, 256)
self.printLock = printLock
# Load style XML
mapnik.load_map(self.m, mapfile, True)
# Obtain <Map> projection
self.prj = mapnik.Projection(self.m.srs)
# Projects between tile pixel co-ordinates and LatLong (EPSG:4326)
self.tileproj = GoogleProjection(maxZoom+1)
def render_tile(self, tile_uri, x, y, z):
# Calculate pixel positions of bottom-left & top-right
p0 = (x * 256, (y + 1) * 256)
p1 = ((x + 1) * 256, y * 256)
# Convert to LatLong (EPSG:4326)
l0 = self.tileproj.fromPixelToLL(p0, z);
l1 = self.tileproj.fromPixelToLL(p1, z);
# Convert to map projection (e.g. mercator co-ords EPSG:900913)
c0 = self.prj.forward(mapnik.Coord(l0[0],l0[1]))
c1 = self.prj.forward(mapnik.Coord(l1[0],l1[1]))
# Bounding box for the tile
if hasattr(mapnik,'mapnik_version') and mapnik.mapnik_version() >= 800:
bbox = mapnik.Box2d(c0.x,c0.y, c1.x,c1.y)
else:
bbox = mapnik.Envelope(c0.x,c0.y, c1.x,c1.y)
render_size = 256
self.m.resize(render_size, render_size)
self.m.zoom_to_box(bbox)
self.m.buffer_size = 128
# Render image with default Agg renderer
im = mapnik.Image(render_size, render_size)
mapnik.render(self.m, im)
im.save(tile_uri, 'png256')
grid_uri = tile_uri.replace('.png','.grid.json')
# new mapnik.Grid api, works like mapnik.Image
# with the exception that you can only render one
# layer to it with the mapnik.render_layer function
# create grid as same size as map/image
grid = mapnik.Grid(render_size, render_size)
# render a layer to that grid array
mapnik.render_layer(self.m,grid,layer=0,fields=['POP2005','NAME'])
# then encode the grid array as utf, resample to 1/4 the size, and dump features
grid_utf = grid.encode('utf',resolution=4,add_features=True)
# below is the old grid api - will be removed soon, don't use
#grid_utf = mapnik.render_grid(self.m,0,key='__id__',resolution=4,fields=['POP2005','NAME'])
# client code uses jsonp, so fake by wrapping in grid() callback
open(grid_uri,'wb').write('grid(' + json.dumps(grid_utf) + ')')
def loop(self):
while True:
#Fetch a tile from the queue and render it
r = self.q.get()
if (r == None):
self.q.task_done()
break
else:
(name, tile_uri, x, y, z) = r
exists= ""
if os.path.isfile(tile_uri):
exists= "exists"
else:
self.render_tile(tile_uri, x, y, z)
bytes=os.stat(tile_uri)[6]
empty= ''
if bytes == 103:
empty = " Empty Tile "
self.printLock.acquire()
print name, ":", z, x, y, exists, empty
self.printLock.release()
self.q.task_done()
def render_tiles(bbox, mapfile, tile_dir, minZoom=1,maxZoom=18, name="unknown", num_threads=NUM_THREADS, tms_scheme=False):
print "render_tiles(",bbox, mapfile, tile_dir, minZoom,maxZoom, name,")"
# Launch rendering threads
queue = Queue(32)
printLock = threading.Lock()
renderers = {}
for i in range(num_threads):
renderer = RenderThread(tile_dir, mapfile, queue, printLock, maxZoom)
render_thread = threading.Thread(target=renderer.loop)
render_thread.start()
#print "Started render thread %s" % render_thread.getName()
renderers[i] = render_thread
if not os.path.isdir(tile_dir):
os.mkdir(tile_dir)
gprj = GoogleProjection(maxZoom+1)
ll0 = (bbox[0],bbox[3])
ll1 = (bbox[2],bbox[1])
for z in range(minZoom,maxZoom + 1):
px0 = gprj.fromLLtoPixel(ll0,z)
px1 = gprj.fromLLtoPixel(ll1,z)
# check if we have directories in place
zoom = "%s" % z
if not os.path.isdir(tile_dir + zoom):
os.mkdir(tile_dir + zoom)
for x in range(int(px0[0]/256.0),int(px1[0]/256.0)+1):
# Validate x co-ordinate
if (x < 0) or (x >= 2**z):
continue
# check if we have directories in place
str_x = "%s" % x
if not os.path.isdir(tile_dir + zoom + '/' + str_x):
os.mkdir(tile_dir + zoom + '/' + str_x)
for y in range(int(px0[1]/256.0),int(px1[1]/256.0)+1):
# Validate x co-ordinate
if (y < 0) or (y >= 2**z):
continue
# flip y to match OSGEO TMS spec
if tms_scheme:
str_y = "%s" % ((2**z-1) - y)
else:
str_y = "%s" % y
tile_uri = tile_dir + zoom + '/' + str_x + '/' + str_y + '.png'
# Submit tile to be rendered into the queue
t = (name, tile_uri, x, y, z)
try:
queue.put(t)
except KeyboardInterrupt:
raise SystemExit("Ctrl-c detected, exiting...")
# Signal render threads to exit by sending empty request to queue
for i in range(num_threads):
queue.put(None)
# wait for pending rendering jobs to complete
queue.join()
for i in range(num_threads):
renderers[i].join()
if __name__ == "__main__":
home = os.environ['HOME']
try:
mapfile = os.environ['MAPNIK_MAP_FILE']
except KeyError:
mapfile = home + "/svn.openstreetmap.org/applications/rendering/mapnik/osm-local.xml"
try:
tile_dir = os.environ['MAPNIK_TILE_DIR']
except KeyError:
tile_dir = home + "/osm/tiles/"
if not tile_dir.endswith('/'):
tile_dir = tile_dir + '/'
#-------------------------------------------------------------------------
#
# Change the following for different bounding boxes and zoom levels
#
# Start with an overview
# World
bbox = (-180.0,-90.0, 180.0,90.0)
render_tiles(bbox, mapfile, tile_dir, 0, 3, "World",tms_scheme=True)
'''
minZoom = 10
maxZoom = 16
bbox = (-2, 50.0,1.0,52.0)
render_tiles(bbox, mapfile, tile_dir, minZoom, maxZoom)
# Muenchen
bbox = (11.4,48.07, 11.7,48.22)
render_tiles(bbox, mapfile, tile_dir, 1, 12 , "Muenchen")
# Muenchen+
bbox = (11.3,48.01, 12.15,48.44)
render_tiles(bbox, mapfile, tile_dir, 7, 12 , "Muenchen+")
# Muenchen++
bbox = (10.92,47.7, 12.24,48.61)
render_tiles(bbox, mapfile, tile_dir, 7, 12 , "Muenchen++")
# Nuernberg
bbox=(10.903198,49.560441,49.633534,11.038085)
render_tiles(bbox, mapfile, tile_dir, 10, 16, "Nuernberg")
# Karlsruhe
bbox=(8.179113,48.933617,8.489252,49.081707)
render_tiles(bbox, mapfile, tile_dir, 10, 16, "Karlsruhe")
# Karlsruhe+
bbox = (8.3,48.95,8.5,49.05)
render_tiles(bbox, mapfile, tile_dir, 1, 16, "Karlsruhe+")
# Augsburg
bbox = (8.3,48.95,8.5,49.05)
render_tiles(bbox, mapfile, tile_dir, 1, 16, "Augsburg")
# Augsburg+
bbox=(10.773251,48.369594,10.883834,48.438577)
render_tiles(bbox, mapfile, tile_dir, 10, 14, "Augsburg+")
# Europe+
bbox = (1.0,10.0, 20.6,50.0)
render_tiles(bbox, mapfile, tile_dir, 1, 11 , "Europe+")
'''