try to improve earth model a bit

git-svn-id: https://svn.spreadspace.org/mur.sat@328 7de4ea59-55d0-425e-a1af-a3118ea81d4c

1 files changed, 6 insertions, 3 deletions

diff --git a/tools/photodiodesim/pd_sim.py b/tools/photodiodesim/pd_sim.py
index 14cbd22..33572c1 100755
--- a/tools/photodiodesim/pd_sim.py
+++ b/tools/photodiodesim/pd_sim.py
@@ -39,7 +39,9 @@ moon = [1,1,1]
 #~ earth = [-1,-2,-1]
 #~ moon = [-1,2,-1]
 sun_intensity = 1.0
-earth_reflection_intensity = 0.10 * sun_intensity # 0 to turn earth off ;-)
+#raised earth_reflection_intensity to account not only for light from a single ray but for multiple rays reflected from a surface.
+#todo: this should propably be included in the earth model instead, once I find good way to do that
+earth_reflection_intensity = 0.50 * sun_intensity # 0 to turn earth off ;-)
 moon_reflection_intensity = 0.07 * sun_intensity # 0 to turn moon off ;-)
 orbit_height = 310e3 #m
 numperiods = 4
@@ -133,7 +135,8 @@ def earthdisc_light_rel_intensity(angle):
         return 0.0
     #todo: factor in angle of actually lightened surface depending on angle_sun_earth and the angle between sat orbit and the sun
     elif angle < angle_earthdisc_visible:
-        return 1.0
+        #account for varying reflection of different earth surface materials [0.75 .. 1.25]
+        return 1.0 + (np.random.ranf() - 0.5)/4.0
     else:
         return sensor_model(angle - angle_earthdisc_visible)
 
@@ -175,7 +178,7 @@ for cur_rot in angular_speed_sum_vectors:
         sun_intensity * np.array([sun_model(a) for a in angles_to_sun]) + \
         earth_reflection_intensity * np.array([earth_model(a) for a in angles_to_earth]) + \
         moon_reflection_intensity * np.array([moon_model(a) for a in angles_to_moon])
-    senstrace.append(light_intensity_per_sensor)
+    senstrace.append(np.minimum(1.0, light_intensity_per_sensor))
 
     suntrace.append(angles_to_sun)
     earthtrace.append(angles_to_earth)