#
# CORE
# Copyright (c)2010-2013 the Boeing Company.
# See the LICENSE file included in this distribution.
#
# author: Jeff Ahrenholz <jeffrey.m.ahrenholz@boeing.com>
#
'''
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.conf import ConfigurableManager
from core.api import coreapi
from core.misc import utm
class CoreLocation(ConfigurableManager):
''' 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.
TODO: this could be updated to use more generic
Configurable/ConfigurableManager code like other Session objects
'''
_name = "location"
_type = coreapi.CORE_TLV_REG_UTILITY
def __init__(self, session):
ConfigurableManager.__init__(self, session)
self.reset()
self.zonemap = {}
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 configure_values(self, msg, values):
''' Receive configuration message for setting the reference point
and scale.
'''
if values is None:
self.session.info("location data missing")
return None
values = values.split('|')
# Cartesian coordinate reference point
refx,refy = map(lambda x: float(x), values[0:2])
refz = 0.0
self.refxyz = (refx, refy, refz)
# Geographic reference point
lat,long,alt = map(lambda x: float(x), values[2:5])
self.setrefgeo(lat, long, alt)
self.refscale = float(values[5])
self.session.info("location configured: (%.2f,%.2f,%.2f) = "
"(%.5f,%.5f,%.5f) scale=%.2f" %
(self.refxyz[0], self.refxyz[1], self.refxyz[2], self.refgeo[0],
self.refgeo[1], self.refgeo[2], self.refscale))
self.session.info("location configured: UTM(%.5f,%.5f,%.5f)" %
(self.refutm[1], self.refutm[2], self.refutm[3]))
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.
'''
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.
'''
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.
'''
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.
'''
# shift (x,y,z) over to reference point (x,y,z)
x = x - self.refxyz[0]
y = -(y - self.refxyz[1])
if z is None:
z = self.refxyz[2]
else:
z = 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:
self.info("UTM out of range error for e=%s n=%s zone=%s" \
"xyz=(%s,%s,%s)" % (e, 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.
'''
# 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.
'''
rzonen = int(self.refutm[0][0])
if zonen == rzonen:
return None # same zone number, no x shift required
z = (zonen, zonel)
if z in self.zoneshifts and self.zoneshifts[z][0] is not None:
return self.zoneshifts[z][0] # x shift already calculated, cached
(rlat, rlon, ralt) = self.refgeo
lon2 = rlon + 6*(zonen - rzonen) # ea. zone is 6deg band
(e2, n2, zonen2, zonel2) = utm.from_latlon(rlat, lon2) # ignore northing
# 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.
'''
rzonel = self.refutm[0][1]
if zonel == rzonel:
return None # same zone letter, no y shift required
z = (zonen, zonel)
if z in self.zoneshifts and self.zoneshifts[z][1] is not None:
return self.zoneshifts[z][1] # y shift already calculated, cached
(rlat, rlon, ralt) = self.refgeo
# zonemap is used to calculate degrees difference between zone letters
latshift = self.zonemap[zonel] - self.zonemap[rzonel]
lat2 = rlat + latshift # ea. latitude band is 8deg high
(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.
'''
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)