Error in the implementation of tile coordinates of babel('bing')

[ysig]

Hi,

thank you for this really nice wrapper library.

I have a problem that seems to be related with an implementation error for bing tiles. Given:

from babelgrid import Babel
babel = Babel('bing')
lat, lon = 14.223633, 40.948055

the predicted tile box boundaries:

tile = babel.geo_to_tile(lat, lon, resolution=res)
print(tile.geometry.geojson['coordinates'][0])

are:

((0.0, 40.979898069620155), (0.0, 66.51326044311185), (45.00000000000001, 66.51326044311185), (45.00000000000001, 40.979898069620155))

which clearly doesn't contain the lat, lon point (the mismatch is in the second dimension 40.938055 < 40.979898069620155)

So either I'm not using the correct way for extracting the boundaries or there is a problem in the implementation.

Thanks,

[JoaoCarabetta]

Which resolution are you using?

[JoaoCarabetta]

I ran some tests and everything seems to be looking good.

This map show that the point is inside the polygon for res = 1

from babelgrid import Babel
import folium

res = 1
babel = Babel('bing')
lat, lon = 14.223633, 40.948055

tile = babel.geo_to_tile(lat, lon, resolution=1)

m = folium.Map()
folium.GeoJson(tile.geometry.geojson).add_to(m)
folium.Circle([lat, lon]).add_to(m)
m

And I get that the tile contains the point for all resolutions from 1 to 15

from shapely.geometry import Point

def tile_contains_point(res):
    tile = babel.geo_to_tile(lat, lon, resolution=1).geometry.shapely
    return tile.contains(Point([lat, lon]))

all([tile_contains_point(res) for i in range(1, 15)]) == True

[ysig]

Your code has an error:

def tile_contains_point(res):
    tile = babel.geo_to_tile(lat, lon, resolution=1).geometry.shapely

->

def tile_contains_point(res):
    tile = babel.geo_to_tile(lat, lon, resolution=res).geometry.shapely

The correct code and with two different ways of comparison gives the flaw:

from shapely.geometry import Point
from babelgrid import Babel

babel = Babel('bing')
lat, lon = 14.223633, 40.948055

def tile_contains_point(res):
    tile = babel.geo_to_tile(lat, lon, resolution=res).geometry.shapely
    gs = babel.geo_to_tile(lat, lon, resolution=res).geometry.geojson['coordinates'][0]

    return tile.contains(Point([lat, lon])), in_boundaries(lat, lon, gs)

def in_boundaries(lat, lon, bd):
    min_lat, min_lon = min(a for a,_ in bd), min(b for _,b in bd)
    max_lat, max_lon = max(a for a,_ in bd), max(b for _,b in bd)
    return min_lat <= lat <= max_lat and min_lon <= lon <= max_lon

for res in range(1, 15):
    print('res:', res, ' - ', tile_contains_point(res))
assert all([all(tile_contains_point(res)) for res in range(1, 15)])

Output:

res: 1  -  (True, True)
res: 2  -  (True, True)
res: 3  -  (True, True)
res: 4  -  (False, False)
res: 5  -  (False, False)
res: 6  -  (False, False)
res: 7  -  (False, False)
res: 8  -  (False, False)
res: 9  -  (False, False)
res: 10  -  (False, False)
res: 11  -  (False, False)
res: 12  -  (False, False)
res: 13  -  (False, False)
res: 14  -  (False, False)