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⚡️ Speed up method GDAL2Tiles.generate_openlayers by 8% #30

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⚡️ Speed up method GDAL2Tiles.generate_openlayers by 8% #30

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137 changes: 79 additions & 58 deletions opendm/tiles/gdal2tiles.py
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,8 @@
from osgeo import gdal
from osgeo import osr

_EPSG_SRS_CACHE = {}

try:
from PIL import Image
import numpy
Expand Down Expand Up @@ -209,7 +211,6 @@ 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 +224,11 @@ 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 @@ -712,12 +714,14 @@ def setup_output_srs(input_srs, options):
"""
Setup the desired SRS (based on options)
"""
output_srs = osr.SpatialReference()

if options.profile == 'mercator':
output_srs.ImportFromEPSG(3857)
elif options.profile == 'geodetic':
output_srs.ImportFromEPSG(4326)
profile = options.profile

# Use cached instances for standard profiles; else copy input_srs
if profile == 'mercator':
# Use a clone to avoid potential mutation of cached SRS
output_srs = _get_epsg_srs(3857).Clone()
elif profile == 'geodetic':
output_srs = _get_epsg_srs(4326).Clone()
else:
output_srs = input_srs

Expand Down Expand Up @@ -2456,25 +2460,29 @@ def generate_openlayers(self):
title, bingkey, north, south, east, west, minzoom, maxzoom, tilesize, tileformat, publishurl
"""

args = {}
args['title'] = self.options.title
args['bingkey'] = self.options.bingkey
args['south'], args['west'], args['north'], args['east'] = self.swne
args['minzoom'] = self.tminz
args['maxzoom'] = self.tmaxz
args['tilesize'] = self.tilesize
args['tileformat'] = self.tileext
args['publishurl'] = self.options.url
args['copyright'] = self.options.copyright
if self.options.tmscompatible:
args['tmsoffset'] = "-1"
else:
args['tmsoffset'] = ""
args = {
'title': self.options.title,
'bingkey': self.options.bingkey,
'south': self.swne[0], 'west': self.swne[1], 'north': self.swne[2], 'east': self.swne[3],
'minzoom': self.tminz,
'maxzoom': self.tmaxz,
'tilesize': self.tilesize,
'tileformat': self.tileext,
'publishurl': self.options.url,
'copyright': self.options.copyright,
}
args['tmsoffset'] = "-1" if self.options.tmscompatible else ""

# Pre-calculate raster parameters for profile == 'raster'
if self.options.profile == 'raster':
args['rasterzoomlevels'] = self.tmaxz+1
args['rasterzoomlevels'] = self.tmaxz + 1
args['rastermaxresolution'] = 2**(self.nativezoom) * self.out_gt[1]

s = r"""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
# Build HTML string blocks efficiently using a list and join
html_parts = []

# Top level styles/header
html_parts.append(r"""<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
<head>
<title>%(title)s</title>
Expand All @@ -2488,14 +2496,16 @@ def generate_openlayers(self):
#map { height: 95%%; border: 1px solid #888; }
.olImageLoadError { display: none; }
.olControlLayerSwitcher .layersDiv { border-radius: 10px 0 0 10px; }
</style>""" % args # noqa
</style>""" % args)

# JS for Google Maps API for mercator profile only (avoid condition inside append to minimize string formatting calls)
if self.options.profile == 'mercator':
s += """
html_parts.append("""
<script src='http://maps.google.com/maps/api/js?sensor=false&v=3.7'></script>
""" % args
""")

s += """
# OpenLayers JS common block
html_parts.append("""
<script src="http://www.openlayers.org/api/2.12/OpenLayers.js"></script>
<script>
var map;
Expand All @@ -2505,10 +2515,12 @@ def generate_openlayers(self):
var emptyTileURL = "http://www.maptiler.org/img/none.png";
OpenLayers.IMAGE_RELOAD_ATTEMPTS = 3;

function init(){""" % args
function init(){""" % args)

if self.options.profile == 'mercator':
s += """
# Profile-dependent blocks
profile = self.options.profile
if profile == 'mercator':
html_parts.append("""
var options = {
div: "map",
controls: [],
Expand Down Expand Up @@ -2586,10 +2598,9 @@ def generate_openlayers(self):
switcherControl.maximizeControl();

map.zoomToExtent(mapBounds.transform(map.displayProjection, map.projection));
""" % args # noqa

elif self.options.profile == 'geodetic':
s += """
""" % args)
elif profile == 'geodetic':
html_parts.append("""
var options = {
div: "map",
controls: [],
Expand Down Expand Up @@ -2624,10 +2635,9 @@ def generate_openlayers(self):
switcherControl.maximizeControl();

map.zoomToExtent(mapBounds);
""" % args # noqa

elif self.options.profile == 'raster':
s += """
""" % args)
elif profile == 'raster':
html_parts.append("""
var options = {
div: "map",
controls: [],
Expand All @@ -2648,19 +2658,21 @@ def generate_openlayers(self):

map.addLayer(layer);
map.zoomToExtent(mapBounds);
""" % args # noqa
""" % args)

s += """
# Controls always added
html_parts.append("""
map.addControls([new OpenLayers.Control.PanZoomBar(),
new OpenLayers.Control.Navigation(),
new OpenLayers.Control.MousePosition(),
new OpenLayers.Control.ArgParser(),
new OpenLayers.Control.Attribution()]);
}
""" % args
""")

if self.options.profile == 'mercator':
s += """
# Profile-dependent getURL js block
if profile == 'mercator':
html_parts.append("""
function getURL(bounds) {
bounds = this.adjustBounds(bounds);
var res = this.getServerResolution();
Expand All @@ -2681,10 +2693,9 @@ def generate_openlayers(self):
return emptyTileURL;
}
}
""" % args # noqa

elif self.options.profile == 'geodetic':
s += """
""" % args)
elif profile == 'geodetic':
html_parts.append("""
function getURL(bounds) {
bounds = this.adjustBounds(bounds);
var res = this.getServerResolution();
Expand All @@ -2702,10 +2713,9 @@ def generate_openlayers(self):
return emptyTileURL;
}
}
""" % args # noqa

elif self.options.profile == 'raster':
s += """
""" % args)
elif profile == 'raster':
html_parts.append("""
function getURL(bounds) {
bounds = this.adjustBounds(bounds);
var res = this.getServerResolution();
Expand All @@ -2723,9 +2733,10 @@ def generate_openlayers(self):
return emptyTileURL;
}
}
""" % args # noqa
""" % args)

s += """
# Window sizing/resizing JS functions
html_parts.append("""
function getWindowHeight() {
if (self.innerHeight) return self.innerHeight;
if (document.documentElement && document.documentElement.clientHeight)
Expand Down Expand Up @@ -2765,8 +2776,10 @@ def generate_openlayers(self):
<div id="map"></div>
<script type="text/javascript" >resize()</script>
</body>
</html>""" % args # noqa
</html>""" % args)

# Join all string parts efficiently
s = ''.join(html_parts)
return s


Expand Down Expand Up @@ -2942,6 +2955,14 @@ def main():
else:
multi_threaded_tiling(input_file, output_folder, options)

def _get_epsg_srs(epsg_code):
srs = _EPSG_SRS_CACHE.get(epsg_code)
if srs is None:
srs = osr.SpatialReference()
srs.ImportFromEPSG(epsg_code)
_EPSG_SRS_CACHE[epsg_code] = srs
return srs


if __name__ == '__main__':
main()
Expand Down