"""
location.py: definition of CoreLocation class that is a member of the
Session object. Provides conversions between Cartesian and geographic coordinate
systems. Depends on utm contributed module, from
https://pypi.python.org/pypi/utm (version 0.3.0).
"""
from core import logger
from core.enumerations import RegisterTlvs
from core.misc import utm
class CoreLocation(object):
"""
Member of session class for handling global location data. This keeps
track of a latitude/longitude/altitude reference point and scale in
order to convert between X,Y and geo coordinates.
"""
name = "location"
config_type = RegisterTlvs.UTILITY.value
def __init__(self):
"""
Creates a MobilityManager instance.
:return: nothing
"""
# ConfigurableManager.__init__(self)
self.reset()
self.zonemap = {}
self.refxyz = (0.0, 0.0, 0.0)
self.refscale = 1.0
self.zoneshifts = {}
self.refgeo = (0.0, 0.0, 0.0)
for n, l in utm.ZONE_LETTERS:
self.zonemap[l] = n
def reset(self):
"""
Reset to initial state.
"""
# (x, y, z) coordinates of the point given by self.refgeo
self.refxyz = (0.0, 0.0, 0.0)
# decimal latitude, longitude, and altitude at the point (x, y, z)
self.setrefgeo(0.0, 0.0, 0.0)
# 100 pixels equals this many meters
self.refscale = 1.0
# cached distance to refpt in other zones
self.zoneshifts = {}
def px2m(self, val):
"""
Convert the specified value in pixels to meters using the
configured scale. The scale is given as s, where
100 pixels = s meters.
:param val: value to use in converting to meters
:return: value converted to meters
"""
return (val / 100.0) * self.refscale
def m2px(self, val):
"""
Convert the specified value in meters to pixels using the
configured scale. The scale is given as s, where
100 pixels = s meters.
:param val: value to convert to pixels
:return: value converted to pixels
"""
if self.refscale == 0.0:
return 0.0
return 100.0 * (val / self.refscale)
def setrefgeo(self, lat, lon, alt):
"""
Record the geographical reference point decimal (lat, lon, alt)
and convert and store its UTM equivalent for later use.
:param lat: latitude
:param lon: longitude
:param alt: altitude
:return: nothing
"""
self.refgeo = (lat, lon, alt)
# easting, northing, zone
e, n, zonen, zonel = utm.from_latlon(lat, lon)
self.refutm = ((zonen, zonel), e, n, alt)
def getgeo(self, x, y, z):
"""
Given (x, y, z) Cartesian coordinates, convert them to latitude,
longitude, and altitude based on the configured reference point
and scale.
:param x: x value
:param y: y value
:param z: z value
:return: lat, lon, alt values for provided coordinates
:rtype: tuple
"""
# shift (x,y,z) over to reference point (x,y,z)
x -= self.refxyz[0]
y = -(y - self.refxyz[1])
if z is None:
z = self.refxyz[2]
else:
z -= self.refxyz[2]
# use UTM coordinates since unit is meters
zone = self.refutm[0]
if zone == "":
raise ValueError("reference point not configured")
e = self.refutm[1] + self.px2m(x)
n = self.refutm[2] + self.px2m(y)
alt = self.refutm[3] + self.px2m(z)
(e, n, zone) = self.getutmzoneshift(e, n)
try:
lat, lon = utm.to_latlon(e, n, zone[0], zone[1])
except utm.OutOfRangeError:
logger.exception("UTM out of range error for n=%s zone=%s xyz=(%s,%s,%s)", n, zone, x, y, z)
lat, lon = self.refgeo[:2]
# self.info("getgeo(%s,%s,%s) e=%s n=%s zone=%s lat,lon,alt=" \
# "%.3f,%.3f,%.3f" % (x, y, z, e, n, zone, lat, lon, alt))
return lat, lon, alt
def getxyz(self, lat, lon, alt):
"""
Given latitude, longitude, and altitude location data, convert them
to (x, y, z) Cartesian coordinates based on the configured
reference point and scale. Lat/lon is converted to UTM meter
coordinates, UTM zones are accounted for, and the scale turns
meters to pixels.
:param lat: latitude
:param lon: longitude
:param alt: altitude
:return: converted x, y, z coordinates
:rtype: tuple
"""
# convert lat/lon to UTM coordinates in meters
e, n, zonen, zonel = utm.from_latlon(lat, lon)
rlat, rlon, ralt = self.refgeo
xshift = self.geteastingshift(zonen, zonel)
if xshift is None:
xm = e - self.refutm[1]
else:
xm = e + xshift
yshift = self.getnorthingshift(zonen, zonel)
if yshift is None:
ym = n - self.refutm[2]
else:
ym = n + yshift
zm = alt - ralt
# shift (x,y,z) over to reference point (x,y,z)
x = self.m2px(xm) + self.refxyz[0]
y = -(self.m2px(ym) + self.refxyz[1])
z = self.m2px(zm) + self.refxyz[2]
return x, y, z
def geteastingshift(self, zonen, zonel):
"""
If the lat, lon coordinates being converted are located in a
different UTM zone than the canvas reference point, the UTM meters
may need to be shifted.
This picks a reference point in the same longitudinal band
(UTM zone number) as the provided zone, to calculate the shift in
meters for the x coordinate.
:param zonen: zonen
:param zonel: zone1
:return: the x shift value
"""
rzonen = int(self.refutm[0][0])
# same zone number, no x shift required
if zonen == rzonen:
return None
z = (zonen, zonel)
# x shift already calculated, cached
if z in self.zoneshifts and self.zoneshifts[z][0] is not None:
return self.zoneshifts[z][0]
rlat, rlon, ralt = self.refgeo
# ea. zone is 6deg band
lon2 = rlon + 6 * (zonen - rzonen)
# ignore northing
e2, n2, zonen2, zonel2 = utm.from_latlon(rlat, lon2)
# NOTE: great circle distance used here, not reference ellipsoid!
xshift = utm.haversine(rlon, rlat, lon2, rlat) - e2
# cache the return value
yshift = None
if z in self.zoneshifts:
yshift = self.zoneshifts[z][1]
self.zoneshifts[z] = (xshift, yshift)
return xshift
def getnorthingshift(self, zonen, zonel):
"""
If the lat, lon coordinates being converted are located in a
different UTM zone than the canvas reference point, the UTM meters
may need to be shifted.
This picks a reference point in the same latitude band (UTM zone letter)
as the provided zone, to calculate the shift in meters for the
y coordinate.
:param zonen: zonen
:param zonel: zone1
:return: calculated y shift
"""
rzonel = self.refutm[0][1]
# same zone letter, no y shift required
if zonel == rzonel:
return None
z = (zonen, zonel)
# y shift already calculated, cached
if z in self.zoneshifts and self.zoneshifts[z][1] is not None:
return self.zoneshifts[z][1]
rlat, rlon, ralt = self.refgeo
# zonemap is used to calculate degrees difference between zone letters
latshift = self.zonemap[zonel] - self.zonemap[rzonel]
# ea. latitude band is 8deg high
lat2 = rlat + latshift
e2, n2, zonen2, zonel2 = utm.from_latlon(lat2, rlon)
# NOTE: great circle distance used here, not reference ellipsoid
yshift = -(utm.haversine(rlon, rlat, rlon, lat2) + n2)
# cache the return value
xshift = None
if z in self.zoneshifts:
xshift = self.zoneshifts[z][0]
self.zoneshifts[z] = (xshift, yshift)
return yshift
def getutmzoneshift(self, e, n):
"""
Given UTM easting and northing values, check if they fall outside
the reference point's zone boundary. Return the UTM coordinates in a
different zone and the new zone if they do. Zone lettering is only
changed when the reference point is in the opposite hemisphere.
:param e: easting value
:param n: northing value
:return: modified easting, northing, and zone values
:rtype: tuple
"""
zone = self.refutm[0]
rlat, rlon, ralt = self.refgeo
if e > 834000 or e < 166000:
num_zones = (int(e) - 166000) / (utm.R / 10)
# estimate number of zones to shift, E (positive) or W (negative)
rlon2 = self.refgeo[1] + (num_zones * 6)
e2, n2, zonen2, zonel2 = utm.from_latlon(rlat, rlon2)
xshift = utm.haversine(rlon, rlat, rlon2, rlat)
# after >3 zones away from refpt, the above estimate won't work
# (the above estimate could be improved)
if not 100000 <= (e - xshift) < 1000000:
# move one more zone away
num_zones = (abs(num_zones) + 1) * (abs(num_zones) / num_zones)
rlon2 = self.refgeo[1] + (num_zones * 6)
e2, n2, zonen2, zonel2 = utm.from_latlon(rlat, rlon2)
xshift = utm.haversine(rlon, rlat, rlon2, rlat)
e = e - xshift
zone = (zonen2, zonel2)
if n < 0:
# refpt in northern hemisphere and we crossed south of equator
n += 10000000
zone = (zone[0], 'M')
elif n > 10000000:
# refpt in southern hemisphere and we crossed north of equator
n -= 10000000
zone = (zone[0], 'N')
return e, n, zone