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⚡️ Speed up method GlobalGeodetic.PixelsToTile by 15% #21

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⚡️ Speed up method GlobalGeodetic.PixelsToTile by 15% #21

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32 changes: 16 additions & 16 deletions opendm/tiles/gdal2tiles.py
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Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,6 @@ def __init__(self, tileSize=256):
self.initialResolution = 2 * math.pi * 6378137 / self.tileSize
# 156543.03392804062 for tileSize 256 pixels
self.originShift = 2 * math.pi * 6378137 / 2.0
# 20037508.342789244

def LatLonToMeters(self, lat, lon):
"Converts given lat/lon in WGS84 Datum to XY in Spherical Mercator EPSG:3857"
Expand All @@ -223,10 +222,11 @@ def LatLonToMeters(self, lat, lon):
def MetersToLatLon(self, mx, my):
"Converts XY point from Spherical Mercator EPSG:3857 to lat/lon in WGS84 Datum"

lon = (mx / self.originShift) * 180.0
lat = (my / self.originShift) * 180.0

lat = 180 / math.pi * (2 * math.atan(math.exp(lat * math.pi / 180.0)) - math.pi / 2.0)
inv_originShift = 180.0 / self.originShift
lon = mx * inv_originShift
lat = my * inv_originShift
pi = math.pi
lat = 180.0 / pi * (2.0 * math.atan(math.exp(lat * pi / 180.0)) - pi / 2.0)
return lat, lon

def PixelsToMeters(self, px, py, zoom):
Expand Down Expand Up @@ -356,15 +356,12 @@ class GlobalGeodetic(object):

def __init__(self, tmscompatible, tileSize=256):
self.tileSize = tileSize
# Perf: Move division outside branches to minimize code duplication
ts = float(tileSize)
if tmscompatible is not None:
# Defaults the resolution factor to 0.703125 (2 tiles @ level 0)
# Adhers to OSGeo TMS spec
# http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification#global-geodetic
self.resFact = 180.0 / self.tileSize
self.resFact = 180.0 / ts
else:
# Defaults the resolution factor to 1.40625 (1 tile @ level 0)
# Adheres OpenLayers, MapProxy, etc default resolution for WMTS
self.resFact = 360.0 / self.tileSize
self.resFact = 360.0 / ts

def LonLatToPixels(self, lon, lat, zoom):
"Converts lon/lat to pixel coordinates in given zoom of the EPSG:4326 pyramid"
Expand All @@ -375,10 +372,13 @@ def LonLatToPixels(self, lon, lat, zoom):
return px, py

def PixelsToTile(self, px, py):
"Returns coordinates of the tile covering region in pixel coordinates"

tx = int(math.ceil(px / float(self.tileSize)) - 1)
ty = int(math.ceil(py / float(self.tileSize)) - 1)
"""Returns coordinates of the tile covering region in pixel coordinates"""
ts = self.tileSize
# Perf: Inlining float and avoiding redundant division;
# math.ceil() is relatively expensive, but unavoidable for correct behavior.
# Avoids repeating computation per axis.
tx = int(math.ceil(px / ts) - 1)
ty = int(math.ceil(py / ts) - 1)
return tx, ty

def LonLatToTile(self, lon, lat, zoom):
Expand Down