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skyplot: split satellite tracks at horizon crossings to avoid linking disjoint passes

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Added logic to segment satellite trajectories whenever elevation drops below 5 degrees, preventing lines from connecting points across horizon gaps. Each segment is plotted independently with its own arrow and label
This commit is contained in:
Carles Fernandez
2025-08-14 09:39:52 +02:00
parent 1031637c8f
commit 42b52f2d66
1 changed files with 38 additions and 41 deletions
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79
utils/skyplot/skyplot.py
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@@ -405,19 +405,16 @@ def plot_satellite_tracks(satellites, obs_lat, obs_lon, obs_alt,
for prn, ephemeris_list in satellites.items(): for prn, ephemeris_list in satellites.items():
color = system_colors.get(prn[0], 'purple') # Default to purple for unknown systems color = system_colors.get(prn[0], 'purple') # Default to purple for unknown systems
# Get the most recent ephemeris
if not ephemeris_list: if not ephemeris_list:
continue continue
mid_time = start_time + (end_time - start_time) / 2 mid_time = start_time + (end_time - start_time) / 2
prev_eph = [e for e in ephemeris_list if e['epoch'] <= mid_time] # Previous ephemeris prev_eph = [e for e in ephemeris_list if e['epoch'] <= mid_time]
if prev_eph:
if prev_eph: # Pick the most recent ephemeris before or at the midpoint
ephemeris = max(prev_eph, key=lambda e: e['epoch']) ephemeris = max(prev_eph, key=lambda e: e['epoch'])
else: # Pick the ephemeris whose epoch is closest in time to the midpoint else:
ephemeris = min(ephemeris_list, key=lambda e: abs((e['epoch'] - mid_time).total_seconds())) ephemeris = min(ephemeris_list, key=lambda e: abs((e['epoch'] - mid_time).total_seconds()))
# Calculate trajectory
if start_time is None or end_time is None: if start_time is None or end_time is None:
all_epochs = sorted({e['epoch'] for prn_data in satellites.values() for e in prn_data}) all_epochs = sorted({e['epoch'] for prn_data in satellites.values() for e in prn_data})
start_time = min(all_epochs) start_time = min(all_epochs)
@@ -425,50 +422,54 @@ def plot_satellite_tracks(satellites, obs_lat, obs_lon, obs_alt,
positions = calculate_satellite_positions(ephemeris, start_time, end_time) positions = calculate_satellite_positions(ephemeris, start_time, end_time)
az = [] # Split into visible segments
el = [] segments = []
current_seg_az = []
current_seg_el = []
for _, x, y, z in positions: for _, x, y, z in positions:
azimuth, elevation = ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt) azimuth, elevation = ecef_to_az_el(x, y, z, obs_lat, obs_lon, obs_alt)
if elevation > 5: # Above horizon if elevation > 5:
az.append(azimuth) current_seg_az.append(azimuth)
el.append(elevation) current_seg_el.append(elevation)
else:
if len(current_seg_az) > 1:
segments.append((current_seg_az, current_seg_el))
current_seg_az, current_seg_el = [], []
if len(current_seg_az) > 1:
segments.append((current_seg_az, current_seg_el))
if len(az) > 1: # Plot each segment separately
# Convert to polar coordinates for az_seg, el_seg in segments:
theta = np.radians(az) theta = np.radians(az_seg)
r = 90 - np.array(el) r = 90 - np.array(el_seg)
# Plot trajectory
ax.plot(theta, r, '-', color=color, alpha=0.7, linewidth=2.5) ax.plot(theta, r, '-', color=color, alpha=0.7, linewidth=2.5)
# Add arrow at last point # Arrow at end
if len(theta) >= 2: # Need at least 2 points for direction if len(theta) >= 2:
dx = theta[-1] - theta[-2] dx = theta[-1] - theta[-2]
dy = r[-1] - r[-2] dy = r[-1] - r[-2]
# Extend endpoint
arrow_length_factor = 1.3 arrow_length_factor = 1.3
extended_theta = theta[-2] + dx * arrow_length_factor extended_theta = theta[-2] + dx * arrow_length_factor
extended_r = r[-2] + dy * arrow_length_factor extended_r = r[-2] + dy * arrow_length_factor
ax.annotate('', ax.annotate('',
xytext=(theta[-1], r[-1]), xytext=(theta[-1], r[-1]),
xy=(extended_theta, extended_r), xy=(extended_theta, extended_r),
arrowprops={ arrowprops={
'arrowstyle': '->', 'arrowstyle': '->',
'color': color, 'color': color,
'alpha': 0.9, 'alpha': 0.9,
'linewidth': 1.5, 'linewidth': 1.5,
'shrinkA': 0, 'shrinkA': 0,
'shrinkB': 0 'shrinkB': 0
}) })
# Label at midpoint # Label at midpoint of the segment
mid_idx = len(theta)//2 mid_idx = len(theta)//2
ax.text(theta[mid_idx], r[mid_idx], prn, ax.text(theta[mid_idx], r[mid_idx], prn,
fontsize=12, ha='center', va='center', fontsize=12, ha='center', va='center',
bbox={"facecolor": "white", "alpha": 0.8, "pad": 2}) bbox={"facecolor": "white", "alpha": 0.8, "pad": 2})
# Create legend elements only for present systems # Legend for present systems
legend_elements = [ legend_elements = [
plt.Line2D([0], [0], marker='o', color='w', plt.Line2D([0], [0], marker='o', color='w',
label=f'{system_names[sys]} ({sys})', label=f'{system_names[sys]} ({sys})',
@@ -476,15 +477,11 @@ def plot_satellite_tracks(satellites, obs_lat, obs_lon, obs_alt,
markersize=10) markersize=10)
for sys in present_systems for sys in present_systems
] ]
# Add legend if we have any systems to show
if legend_elements: if legend_elements:
ax.legend( ax.legend(handles=legend_elements,
handles=legend_elements, loc='upper right',
loc='upper right', bbox_to_anchor=(1.3, 1.1),
bbox_to_anchor=(1.3, 1.1), fontsize=14)
fontsize=14
)
lat_deg = np.degrees(obs_lat) lat_deg = np.degrees(obs_lat)
lon_deg = np.degrees(obs_lon) lon_deg = np.degrees(obs_lon)