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add tests for longlat/merc transformations

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Dane Springmeyer 2013-01-27 17:26:54 -08:00
parent 19526eb7f7
commit 57c99a69a2
1 changed files with 51 additions and 0 deletions
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51
tests/python_tests/projection_test.py
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@ -3,6 +3,8 @@
from nose.tools import *
import mapnik
import random
import math
# Tests that exercise map projections.
@ -46,5 +48,54 @@ def test_wgs84_inverse_forward():
assert_almost_equal(e.forward(p).center().y, e.center().y)
assert_almost_equal(e.forward(p).center().x, e.center().x)
def wgs2merc(lon,lat):
x = lon * 20037508.34 / 180;
y = math.log(math.tan((90 + lat) * math.pi / 360)) / (math.pi / 180);
y = y * 20037508.34 / 180;
return [x,y];
def merc2wgs(x,y):
x = (x / 20037508.34) * 180;
y = (y / 20037508.34) * 180;
y = 180 / math.pi * (2 * math.atan(math.exp(y * math.pi/180)) - math.pi/2);
if x > 180: x = 180;
if x < -180: x = -180;
if y > 85.0511: y = 85.0511;
if y < -85.0511: y = -85.0511;
return [x,y]
#echo -109 37 | cs2cs -f "%.10f" +init=epsg:4326 +to +init=epsg:3857
#-12133824.4964668211 4439106.7872505859 0.0000000000
## todo
# benchmarks
# better well known detection
# better srs matching with strip/trim
# python copy to avoid crash
def test_proj_transform_between_init_and_literal():
one = mapnik.Projection('+init=epsg:4326')
two = mapnik.Projection('+init=epsg:3857')
tr1 = mapnik.ProjTransform(one,two)
wgs84 = '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs'
merc = '+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over'
src = mapnik.Projection(wgs84)
dest = mapnik.Projection(merc)
tr2 = mapnik.ProjTransform(src,dest)
for x in xrange(-180,180,10):
for y in xrange(-60,60,10):
coord = mapnik.Coord(x,y)
merc_coord1 = tr1.forward(coord)
merc_coord2 = tr2.forward(coord)
assert_almost_equal(merc_coord1.x,merc_coord2.x)
assert_almost_equal(merc_coord1.y,merc_coord2.y)
lon_lat_coord1 = tr1.backward(merc_coord1)
lon_lat_coord2 = tr2.backward(merc_coord2)
assert_almost_equal(coord.x,lon_lat_coord1.x)
assert_almost_equal(coord.y,lon_lat_coord1.y)
assert_almost_equal(coord.x,lon_lat_coord2.x)
assert_almost_equal(coord.y,lon_lat_coord2.y)
if __name__ == "__main__":
[eval(run)() for run in dir() if 'test_' in run]