mapnik generate_tiles.py 返回内存错误
我正在尝试使用 generate_tiles.py 创建地图瓦片，但每次运行这个脚本时，都会出现以下错误：
线程 Thread-2 出现异常： 回溯（最近的调用在最前面）： 文件 "/usr/lib/python2.7/threading.py"，第 552 行，在 __bootstrap_inner self.run() 文件 "/usr/lib/python2.7/threading.py"，第 505 行，在 run self.__target(*self.__args, **self.__kwargs) 文件 "render_tiles.py"，第 114 行，在 loop self.render_tile(tile_uri, x, y, z) 文件 "render_tiles.py"，第 96 行，在 render_tile mapnik.render(self.m, im) 内存错误
这是我的脚本。
#!/usr/bin/python
from math import pi,cos,sin,log,exp,atan
from subprocess import call
import sys, os
from Queue import Queue
import mapnik
import threading
import random
import argparse
custom_fonts_dir = '/usr/share/fonts/'
mapnik.register_fonts(custom_fonts_dir)
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[int(zoom)]
e = round(d[0] + float(ll[0]) * self.Bc[zoom])
f = minmax(sin(DEG_TO_RAD * float(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)
# Obtain 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')
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):
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)
print "fromlattolon"
# 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 = 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 = 2**z):
continue
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)
queue.put(t)
# 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__":
MIN_LON = '29.5732';
MAX_LON = '35.0360';
MIN_LAT = '-1.4840';
MAX_LAT = '4.2144';
bbox = ( MIN_LON, MIN_LAT,MAX_LON, MAX_LAT)
style_file="/home/mossplix/projects/Dev/mapit/map/static/tilemill/uganda_districts.xml"
tile_dir="/home/mossplix/projects/UnicefDev/mapit/map/static/tiles/"
min_zoom=7
max_zoom=14
render_tiles(bbox, style_file, tile_dir, min_zoom, max_zoom)
这是 mapnik 的配置文件，mapnik config，还有这个 shapefile。我从源代码编译了 mapnik，所以应该没问题。那可能是什么原因呢？
2 个回答
0
默认的渲染线程数量应该和你电脑的CPU核心数差不多，NUM_THREADS = 4
我遇到的错误和NUM_THREADS=4完全一样。把NUM_THREADS的默认值改成1。我用的是i5处理器（有4个核心，每个核心1个线程），NUM_THREADS=4的时候很不稳定。改成NUM_THREADS=1就没问题了。如果你用NUM_THREADS=1也能正常工作，可以试试NUM_THREADS=2和NUM_THREADS=3，看有没有崩溃。
3
我可以看出这个文件最初是 generate_tiles.py，只是稍微修改了一下。
出现 MemoryError 错误说明你要渲染的图片可能太大了，或者你碰到了 Mapnik 的一个 bug。
因为前者更常见，我觉得你在修改 generate_tiles.py 的时候可能犯了个错误。所以我拿了你的脚本，覆盖了 svn 中的最新版本，并对比了不同之处：https://gist.github.com/1197587。
在第 #106 行和第 #115 行，你可能想用 == 而不是 =，因为如果用错了，你会得到非常大的 x 和 y 值，这些值是无效的，可能导致请求的图片过大（对于某个特定的瓦片来说是错误的）。