Question

我是Openstreetmap和mapnick的新手，

我正在尝试导出将被地理参考的地图图像（因此它可以在其他应用程序中使用）

我在ubuntu虚拟机中安装了osm和mapnik

我尝试过使用generate_image.py脚本，但生成的图像不等于边界框。我的python知识不足以让我修复脚本。

我也尝试过使用详细模式的nik2img.py脚本，例如：

nik2img.py osm.xml sarajevo.png --srs 900913 --bbox 18.227 43.93 18.511 43.765 --dimensions 10000 10000

并尝试使用日志边界框

Step: 11 // --> Map long/lat bbox: Envelope(18.2164733537,43.765,18.5215266463,43.93)

不幸的是，生成的图像不等于边界框:(

如何更改脚本以便我可以对生成的图像进行地理配准？或者您知道更简单的方法来完成这项任务吗？我正在使用http://www.openstreetmap.org/导出的图像很好地被地理参考，但它不够大：（

Answer 1

我已设法更改 generate_tiles.py 以生成1024x1024图像以及正确的边界框

下面提供了更改的脚本

#!/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

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 = 1024
        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(1024, 1024)
        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 * 1024, (y + 1) * 1024)
        p1 = ((x + 1) * 1024, y * 1024)

        # 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 = 1024
        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')
    print "Rendered: ", tile_uri, "; ", l0 , "; ", l1


    # Write geo coding informations 
    file = open(tile_uri[:-4] + ".tab", 'w')
    file.write("!table\n")
    file.write("!version 300\n")
    file.write("!charset WindowsLatin2\n")

    file.write("Definition Table\n")
    file.write("  File \""+tile_uri[:-4]+".jpg\"\n")
    file.write("  Type \"RASTER\"\n")
    file.write("  ("+str(l0[0])+","+str(l1[1])+") (0,0) Label \"Pt 1\",\n")
    file.write("  ("+str(l1[0])+","+str(l1[1])+") (1023,0) Label \"Pt 2\",\n")
    file.write("  ("+str(l1[0])+","+str(l0[1])+") (1023,1023) Label \"Pt 3\",\n")
    file.write("  ("+str(l0[0])+","+str(l0[1])+") (0,1023) Label \"Pt 4\"\n")
    file.write("  CoordSys Earth Projection 1, 104\n")
    file.write("  Units \"degree\"\n")

    file.close()



    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)

        # 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]/1024.0),int(px1[0]/1024.0)+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]/1024.0),int(px1[1]/1024.0)+1):
                # Validate x co-ordinate
                if (y < 0) or (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__":
    home = os.environ['HOME']
    try:
        mapfile = "/home/emir/bin/mapnik/osm.xml" #os.environ['MAPNIK_MAP_FILE']
    except KeyError:
        mapfile = "/home/emir/bin/mapnik/osm.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
    #

    #render sarajevo at 16 zoom level
    bbox = (18.256, 43.785, 18.485, 43.907)
    render_tiles(bbox, mapfile, tile_dir, 16, 16, "World")

Answer 2

尝试Maperitive's export-bitmap命令，它会生成各种地理配准边车文件（worldfile，KML，OziExplorer .MAP文件）。

OpenStreetMap生成地理配准图像

2 个答案: