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Change scale argument to OSM zoom level.

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Use OSM zoom level as specification of the map scale.
This commit is contained in:
Sergey Vartanov 2020-09-19 03:33:25 +03:00
parent 9e14093854
commit 54b88f05d2
3 changed files with 37 additions and 47 deletions
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17
roentgen/flinger.py
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@ -21,20 +21,31 @@ def pseudo_mercator(coordinates: np.array) -> np.array:
np.tan(np.pi / 4 + coordinates[0] * (np.pi / 180) / 2))))
def osm_zoom_level_to_pixels_per_meter(zoom_level: float):
"""
Convert OSM zoom level (see https://wiki.openstreetmap.org/wiki/Zoom_levels)
to pixels per meter on Equator.
"""
return 2 ** zoom_level / 156415
class Flinger:
"""
Convert geo coordinates into SVG position points.
"""
def __init__(self, geo_boundaries: MinMax, ratio: float = 1000):
def __init__(self, geo_boundaries: MinMax, scale: float = 1000):
"""
:param geo_boundaries: minimum and maximum latitude and longitude
:param scale: OSM zoom level
"""
self.geo_boundaries: MinMax = geo_boundaries
self.ratio: float = ratio
self.ratio: float = (
osm_zoom_level_to_pixels_per_meter(scale) *
EQUATOR_LENGTH / 360)
self.size: np.array = self.ratio * (
pseudo_mercator(self.geo_boundaries.max_) -
pseudo_mercator(self.geo_boundaries.min_))
self.pixels_per_meter = 360 / EQUATOR_LENGTH * self.ratio
self.pixels_per_meter = osm_zoom_level_to_pixels_per_meter(scale)
self.size: np.array = self.size.astype(int).astype(float)