Hi all,
I'm trying to render maps in a conic projection. The problem is, that i get
a blank image as result.
If I generate in mercator or latlon there is no problem. I get what I want.
But I can't generate anything in a conical projection.
I modified a script I found, to test different projections. Does anybody
know why it's not working? What's my mistake? Are there parameters that have
to be set?
Thankyou in advance
#!/usr/bin/python
import mapnik
mapfile = "style9_nodem.xml"
projections = {
"latlon": "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs", #EPSG:4326
"google": "+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137
+b=6378137 +units=m +no_defs", # SR-ORG:95
"mercator_world": "+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +ellps=WGS84
+datum=WGS84 +units=m +no_defs", # SR-ORG:16
"lambert": "+proj=lcc +lat_1=49.83333333333334 +lat_2=51.16666666666666
+lat_0=90 +lon_0=0 +x_0=150000 +y_0=5400000 +ellps=intl +pm=brussels
+units=m +no_defs",
"albert": "+proj=aea +lat_1=29.83333333333334 +lat_2=45.83333333333334
+lat_0=37.5 +lon_0=-96 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m
+no_defs",
"pytest": "+proj=lcc +lat_1=45.89893890000052 +lat_2=47.69601440000037
+lat_0=46.8 +lon_0=2.33722917 +x_0=600000 +y_0=200000 +a=6378249.145
+b=6356514.96582849 +pm=2.337229167 +units=m +no_defs",
}
ll = (8.487, 49.9857, 8.6237, 50.0622)
imgx = 1000
imgy = 1000
# Render an image for every projection
for projName, projDef in sorted(projections.items()):
print "Projection: " + projName
# Load the map data
m = mapnik.Map(imgx, imgy)
mapnik.load_map(m, mapfile)
# Override projection defined in osm.xml
m.srs = projDef
# Calculate projected boundaries
prj = mapnik.Projection(projDef)
c0 = prj.forward(mapnik.Coord(ll[0], ll[1]))
c1 = prj.forward(mapnik.Coord(ll[2], ll[3]))
# Apply bounding box
bbox = mapnik.Envelope(c0.x, c0.y, c1.x, c1.y)
m.zoom_to_box(bbox)
# Render image
im = mapnik.Image(imgx, imgy)
mapnik.render(m, im)
view = im.view(0, 0, imgx, imgy)
view.save("img/" + projName + ".png", "png256")
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