def llh2xyz(lat, lon, ellht=0, ellipsoid=grs80):
"""
Converts Geographic Latitude, Longitude and Ellipsoid Height to Cartesian
X, Y and Z Coordinates. Default Ellipsoid parameters used are GRS80.
:param lat: Geographic Latitude
:type lat: Float (Decimal Degrees), DMSAngle or DDMAngle
:param lon: Geographic Longitude
:type lon: Float (Decimal Degrees), DMSAngle or DDMAngle
:param ellht: Ellipsoid Height (metres, default is 0m)
:param ellipsoid: Ellipsoid Object
:type ellipsoid: Ellipsoid
:return: Cartesian X, Y, Z Coordinate in metres
:rtype: tuple
"""
# Convert lat & long to radians
lat = radians(angular_typecheck(lat))
lon = radians(angular_typecheck(lon))
# Calculate Ellipsoid Radius of Curvature in the Prime Vertical - nu
if lat == 0:
nu = grs80.semimaj
else:
nu = ellipsoid.semimaj / (sqrt(1 - ellipsoid.ecc1sq * (sin(lat)**2)))
# Calculate x, y, z
x = (nu + ellht) * cos(lat) * cos(lon)
y = (nu + ellht) * cos(lat) * sin(lon)
z = ((ellipsoid.semimin**2 / ellipsoid.semimaj**2) * nu + ellht) * sin(lat)
return x, y, z
def test_angular_typecheck(self):
class_exs = [deca_exs, hpa_exs, gona_exs, dms_exs, ddm_exs]
for class_ex in class_exs:
for num, ex in enumerate(class_ex):
self.assertAlmostEqual(angular_typecheck(ex), dec_exs[num], 13)
self.assertAlmostEqual(angular_typecheck(-ex), -dec_exs[num],
13)
for ex in dec_exs:
self.assertEqual(angular_typecheck(ex), ex)
self.assertEqual(angular_typecheck(-ex), -ex)
def psfandgridconv(xi1,
eta1,
lat,
lon,
cm,
conf_lat,
ellipsoid=grs80,
prj=utm):
"""
Calculates Point Scale Factor and Grid Convergence. Used in convert.geo2grid
and convert.grid2geo
:param xi1: Transverse Mercator Ratio Xi
:param eta1: Transverse Mercator Ratio Eta
:param lat: Latitude
:type lat: Decimal Degrees, DMSAngle or DDMAngle
:param lon: Longitude
:type lon: Decimal Degrees, DMSAngle or DDMAngle
:param cm: Central Meridian
:param conf_lat: Conformal Latitude
:param ellipsoid: Ellipsoid Object (default: GRS80)
:return: Point Scale Factor, Grid Convergence (Decimal Degrees)
:rtype: tuple
"""
lat = angular_typecheck(lat)
lon = angular_typecheck(lon)
A = rect_radius(ellipsoid)
a = alpha_coeff(ellipsoid)
lat = radians(lat)
long_diff = radians(lon - cm)
# Point Scale Factor
p = 1
q = 0
for r in range(1, 9):
p += 2 * r * a[r - 1] * cos(2 * r * xi1) * cosh(2 * r * eta1)
q += 2 * r * a[r - 1] * sin(2 * r * xi1) * sinh(2 * r * eta1)
q = -q
psf = (float(prj.cmscale) * (A / ellipsoid.semimaj) * sqrt(q**2 + p**2) *
((sqrt(1 + (tan(lat)**2)) * sqrt(1 - ellipsoid.ecc1sq *
(sin(lat)**2))) /
sqrt((tan(conf_lat)**2) + (cos(long_diff)**2))))
# Grid Convergence
grid_conv = degrees(
atan(abs(q / p)) +
atan(abs(tan(conf_lat) * tan(long_diff)) / sqrt(1 + tan(conf_lat)**2)))
if cm > lon and lat < 0:
grid_conv = -grid_conv
elif cm < lon and lat > 0:
grid_conv = -grid_conv
return psf, grid_conv
def polar2rect(r, theta):
"""
Converts point in polar coordinates to corresponding rectangular coordinates
Theta is degrees and is measured clockwise from the positive y axis
(i.e. north)
:param r: Radius
:param theta: Angle (decimal degrees)
:type theta: Float (decimal degrees), DMSAngle or DDMAngle
:return: Rectangular Coordinates X, Y
"""
theta = angular_typecheck(theta)
x = r * sin(radians(theta))
y = r * cos(radians(theta))
return x, y
def geo2grid(lat, lon, zone=0, ellipsoid=grs80):
"""
Takes a geographic co-ordinate (latitude, longitude) and returns its
corresponding Hemisphere, Zone and Projection Easting and Northing, Point
Scale Factor and Grid Convergence. Default Projection is Universal
Transverse Mercator Projection using
GRS80 Ellipsoid parameters.
:param lat: Latitude
:type lat: Float (Decimal Degrees), DMSAngle or DDMAngle
:param lon: Longitude
:type lon: Float (Decimal Degrees, DMSAngle or DDMAngle
:param zone: Optional Zone Number - Only required if calculating grid
co-ordinate outside zone boundaries
:param ellipsoid: Ellipsoid Object
:type ellipsoid: Ellipsoid
:return: hemisphere, zone, east (m), north (m), Point Scale Factor,
Grid Convergence (Decimal Degrees)
:rtype: tuple
"""
# Convert DMSAngle and DDMAngle to Decimal Angle
lat = angular_typecheck(lat)
lon = angular_typecheck(lon)
# Input Validation - UTM Extents and Values
zone = int(zone)
if zone < 0 or zone > 60:
raise ValueError('Invalid Zone - Zones from 1 to 60')
if lat < -80 or lat > 84:
raise ValueError('Invalid Latitude - Latitudes from -80 to +84')
if lon < -180 or lon > 180:
raise ValueError('Invalid Longitude - Longitudes from -180 to +180')
A = rect_radius(ellipsoid)
a = alpha_coeff(ellipsoid)
lat = radians(lat)
# Calculate Zone
if zone == 0:
zone = int((float(lon) - (proj.initialcm - (1.5 * proj.zonewidth))) /
proj.zonewidth)
cm = float(zone * proj.zonewidth) + (proj.initialcm - proj.zonewidth)
# Conformal Latitude
sigx = (ellipsoid.ecc1 * tan(lat)) / sqrt(1 + (tan(lat)**2))
sig = sinh(ellipsoid.ecc1 * (0.5 * log((1 + sigx) / (1 - sigx))))
conf_lat = tan(lat) * sqrt(1 + sig**2) - sig * sqrt(1 + (tan(lat)**2))
conf_lat = atan(conf_lat)
# Longitude Difference
long_diff = radians(lon - cm)
# Gauss-Schreiber Ratios
xi1 = atan(tan(conf_lat) / cos(long_diff))
eta1x = sin(long_diff) / (sqrt(tan(conf_lat)**2 + cos(long_diff)**2))
eta1 = log(eta1x + sqrt(1 + eta1x**2))
# Transverse Mercator Ratios
eta = eta1
xi = xi1
for r in range(1, 9):
eta += a[r - 1] * cos(2 * r * xi1) * sinh(2 * r * eta1)
xi += a[r - 1] * sin(2 * r * xi1) * cosh(2 * r * eta1)
# Transverse Mercator Co-ordinates
x = A * eta
y = A * xi
# Hemisphere-dependent UTM Projection Co-ordinates
east = proj.cmscale * x + proj.falseeast
if y < 0:
hemisphere = 'South'
north = proj.cmscale * y + proj.falsenorth
else:
hemisphere = 'North'
falsenorth = 0
north = proj.cmscale * y + falsenorth
# Point Scale Factor and Grid Convergence
psf, grid_conv = psfandgridconv(xi1, eta1, degrees(lat), lon, cm, conf_lat)
return (hemisphere, zone, round(float(east),
4), round(float(north),
4), round(psf, 8), grid_conv)
