Hello,
i once downloaded two huge TIF from the Nasa web server, they are called
land_shallow_topo_east.tif and land_shallow_topo_west.tif.
I'd like to use these files as background when rendering a map, so i tried in
a modified version of OSM's generate_image.py to add a layer for the east
TIF. I've also set the background in "osm.xml" to "transparent".
The TIF data are not rendered, though. I have copied the python script that
i use for this at the end of this mail.
Can anybody tell me what is going wrong here?
Has anybody else used these files as background?
Is there a better way to use these TIFs as background?
Can anybody confirm / correct the projection data that i need to use for the
TIFs from the Nasa server?
Best regards,
Torsten.
#!/usr/bin/python
# source set-mapnik-environment
#<Map bgcolor="#b5d0d0" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0
+lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgri...@null +no_defs +over">
#<Map bgcolor="transparent" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0
+lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgri...@null +no_defs +over">
from mapnik import *
import sys, os
if __name__ == "__main__":
mapfile = "osm_print.xml"
map_uri = "image.png"
tifdir = "/local/vid/earth"
west = "land_shallow_topo_west.tif"
east = "land_shallow_topo_east.tif"
# ll = (4.5, 46, 16, 56) # Deutschland
ll = (-180.0, -85.0511, 180.0, 85.0511) # Welt, maximum
# ll = (-180.0, -50.0, 180.0, 60.0) # Welt, aspect ration 4:3
z = 10
imgx = 600 * z
imgy = 300 * z
m = Map(imgx, imgy)
r_east = Raster(base = tifdir, file = east, lox = 0.0, loy = -85.0511, hix
= 180.0, hiy = 85.0511)
l_east = Layer('tif_east')
l_east.datasource = r_east
r_west = Raster(base = tifdir, file = west, lox = 0.0, loy = -85.0511, hix
= 180.0, hiy = 85.0511)
l_west = Layer('tif_west')
l_west.datasource = r_west
l_east.active = True
print l_east
m.layers.append(l_east)
load_map(m, mapfile)
for l in m.layers:
print l.name
prj = Projection("+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0
+x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgri...@null +no_defs +over")
c0 = prj.forward(Coord(ll[0], ll[1]))
c1 = prj.forward(Coord(ll[2], ll[3]))
bbox = Envelope(c0.x, c0.y, c1.x, c1.y)
m.zoom_to_box(bbox)
print "scale", m.scale(), 1.0 / m.scale()
print "denom", m.scale_denominator()
im = Image(imgx, imgy)
render(m, im)
view = im.view(0, 0, imgx, imgy)
view.save(map_uri, 'png')
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