def test_half_power_radius(self):
hpr = util.half_power_radius(np.arange(0, 100000, 10000), 1.0)
res = np.array([
0., 87.266, 174.533, 261.799, 349.066, 436.332, 523.599, 610.865,
698.132, 785.398
])
self.assertTrue(np.allclose(hpr, res))
def test_half_power_radius(self):
hpr = util.half_power_radius(np.arange(0, 100000, 10000), 1.0)
res = np.array([0., 87.266, 174.533, 261.799, 349.066, 436.332,
523.599, 610.865, 698.132, 785.398])
self.assertTrue(np.allclose(hpr, res))
def plot_scan_strategy(
ranges,
elevs,
sitecoords,
beamwidth=1.0,
vert_res=500.0,
maxalt=10000.0,
range_res=None,
maxrange=None,
units="m",
terrain=None,
az=0.0,
cg=False,
ax=111,
cmap="tab10",
):
"""Plot the vertical scanning strategy.
Parameters
----------
ranges : sequence of floats
array of ranges
elevs : sequence of floats
elevation angles
sitecoords : sequence of floats
radar site coordinates (longitude, latitude, altitude)
beamwidth : float
3dB width of the radar beam, defaults to 1.0 deg.
vert_res : float
Vertical resolution in [m].
maxalt : float
Maximum altitude in [m].
range_res : float
Horizontal resolution in [m].
maxrange : float
Maximum range in [m].
units : str
Units to plot in, can be 'm' or 'km'. Defaults to 'm'.
terrain : bool | :class:`numpy:numpy.ndarray`
If True, downloads srtm data and add orography for given `az`.
az : float
Used to specify azimuth for terrain plots.
cg : bool
If True, plot in curvelinear grid, defaults to False (cartesian grid).
ax : :class:`matplotlib:matplotlib.axes.Axes` | matplotlib grid definition
If matplotlib Axes object is given, the scan strategy will be plotted into this
axes object.
If matplotlib grid definition is given (nrows/ncols/plotnumber),
axis are created in the specified place.
Defaults to '111', only one subplot/axis.
cmap : str
matplotlib colormap string.
Returns
-------
ax : :class:`matplotlib:matplotlib.axes.Axes` | matplotlib toolkit axisartist Axes object
matplotlib Axes or curvelinear Axes (r-theta-grid) depending on keyword argument `cg`.
"""
if units == "m":
scale = 1.0
elif units == "km":
scale = 1000.0
else:
raise ValueError(
f"wradlib: unknown value for keyword argument units={units}")
az = np.array([az])
if maxrange is None:
maxrange = ranges.max()
xyz, rad = georef.spherical_to_xyz(ranges,
az,
elevs,
sitecoords,
squeeze=True)
add_title = ""
if terrain is True:
add_title += f" - Azimuth {az[0]}°"
ll = georef.reproject(xyz, projection_source=rad)
# (down-)load srtm data
ds = io.get_srtm(
[
ll[..., 0].min(), ll[..., 0].max(), ll[..., 1].min(),
ll[..., 1].max()
],
download={},
)
rastervalues, rastercoords, proj = georef.extract_raster_dataset(
ds, nodata=-32768.0)
# map rastervalues to polar grid points
terrain = ipol.cart_to_irregular_spline(rastercoords,
rastervalues,
ll[-1, ..., :2],
order=3,
prefilter=False)
if ax == 111:
fig = pl.figure(figsize=(16, 8))
else:
fig = pl.gcf()
legend2 = {}
if cg is True:
ax, caax, paax = create_cg(fig=fig, subplot=ax, rot=0, scale=1)
# for nice plotting we assume earth_radius = 6370000 m
er = 6370000
# calculate beam_height and arc_distance for ke=1
# means line of sight
ade = georef.bin_distance(ranges, 0, sitecoords[2], re=er, ke=1.0)
nn0 = np.zeros_like(ranges)
ecp = nn0 + er
# theta (arc_distance sector angle)
thetap = -np.degrees(ade / er) + 90.0
# zero degree elevation with standard refraction
(bes, ) = paax.plot(thetap,
ecp,
"-k",
linewidth=3,
label="_MSL",
zorder=3)
legend2["MSL"] = bes
if terrain is not None:
paax.fill_between(thetap,
ecp.min() - 2500,
ecp + terrain,
color="0.75",
zorder=2)
# axes layout
ax.set_xlim(0, np.max(ade))
ax.set_ylim([ecp.min() - maxalt / 5, ecp.max() + maxalt])
caax.grid(True, axis="x")
ax.grid(True, axis="y")
ax.axis["top"].toggle(all=False)
gh = ax.get_grid_helper()
yrange = maxalt + maxalt / 5
nbins = ((yrange // vert_res) * 2 + 1) // np.sqrt(2)
gh.grid_finder.grid_locator2._nbins = nbins
else:
ax = fig.add_subplot(ax)
paax = ax
caax = ax
if terrain is not None:
paax.fill_between(ranges, 0, terrain, color="0.75", zorder=2)
ax.set_xlim(0.0, maxrange)
ax.set_ylim(0.0, maxalt)
ax.grid()
# axes ticks and formatting
if range_res is not None:
xloc = range_res
caax.xaxis.set_major_locator(MultipleLocator(xloc))
else:
caax.xaxis.set_major_locator(MaxNLocator())
yloc = vert_res
caax.yaxis.set_major_locator(MultipleLocator(yloc))
import functools
hform = functools.partial(_height_formatter, cg=cg, scale=scale)
rform = functools.partial(_range_formatter, scale=scale)
caax.yaxis.set_major_formatter(FuncFormatter(hform))
caax.xaxis.set_major_formatter(FuncFormatter(rform))
# color management
from cycler import cycler
NUM_COLORS = len(elevs)
cmap = pl.get_cmap(cmap)
if cmap.N >= 256:
colors = [cmap(1.0 * i / NUM_COLORS) for i in range(NUM_COLORS)]
else:
colors = cmap.colors
cycle = cycler(color=colors)
paax.set_prop_cycle(cycle)
# plot beams
for i, el in enumerate(elevs):
alt = xyz[i, ..., 2]
groundrange = np.sqrt(xyz[i, ..., 0]**2 + xyz[i, ..., 1]**2)
if cg:
plrange = thetap
plalt = ecp + alt
beamradius = util.half_power_radius(ranges, beamwidth)
else:
plrange = np.insert(groundrange, 0, 0)
plalt = np.insert(alt, 0, sitecoords[2])
beamradius = util.half_power_radius(plrange, beamwidth)
_, center, edge = _plot_beam(plrange,
plalt,
beamradius,
label=f"{el:4.1f}°",
ax=paax)
# legend 1
handles, labels = ax.get_legend_handles_labels()
leg1 = ax.legend(
handles,
labels,
prop={"family": "monospace"},
loc="upper left",
bbox_to_anchor=(1.04, 1),
borderaxespad=0,
)
# legend 2
legend2["Center"] = center[0]
legend2["3 dB"] = edge[0]
ax.legend(
legend2.values(),
legend2.keys(),
prop={"family": "monospace"},
loc="lower left",
bbox_to_anchor=(1.04, 0),
borderaxespad=0,
)
# add legend 1
ax.add_artist(leg1)
# set axes labels
ax.set_title(f"Radar Scan Strategy - {sitecoords}" + add_title)
caax.set_xlabel(f"Range ({units})")
caax.set_ylabel(f"Altitude ({units})")
return ax