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glint.py
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glint.py
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import sys
import spice
rpd,dpr = spice.rpd(),spice.dpr()
if __name__=="__main__":
spice.furnsh(__file__)
### Earth equatorial and polar radii calculate flattening
re = spice.gdpool('BODY399_RADII',0,1)[1]
rp = spice.gdpool('BODY399_RADII',2,1)[1]
f = (re-rp) / re
for line in sys.stdin:
### Read one line of input at a time; only use lines that start with data:
if line[:5]!="data:": continue
linestrip = line[5:].strip()
linetoks = linestrip.split() ### Break line into tokens
toms_alt_m,toms_lon_deg,toms_lat_deg,sX,sY,sZ,surf_lon_deg,surf_lat_deg = map(float,linetoks[:-1])
utc = linetoks[-1]
uvEarth2Sun = spice.vhat((sX,sY,sZ,)) ### Ensure Sun vector is unit length
toms_alt_km = 1e-3 * toms_alt_m ### Scale altitude to km
toms_lon_rad = rpd * toms_lon_deg ### Scale degrees to radians
toms_lat_rad = rpd * toms_lat_deg ### Scale degrees to radians
surf_lon_rad = rpd * surf_lon_deg
surf_lat_rad = rpd * surf_lat_deg
####################################################################
### End of input processing, make calculations (5 steps)
####################################################################
### Convert TOMS and surface points geodetic positions to ECEF vectors
toms_vec = spice.georec(toms_lon_rad,toms_lat_rad,toms_alt_km,re,f)
surfPoint = spice.georec(surf_lon_rad,surf_lat_rad,0.,re,f)
### Get normal at surface point, ECEF unit vector
uvSurfNormal = spice.surfnm(re,re,rp,surfPoint)
### Get cosine of incidence angle (angle between Sun & surface normal vector)
mu = spice.vdot(uvEarth2Sun,uvSurfNormal)
if mu <= 0.:
print('%s => %7s' % (linestrip,'Surface point is dark',)) ### Sun is below surface horizon
continue
uvReflect = spice.vsub(spice.vscl(2.*mu,uvSurfNormal),uvEarth2Sun) ### Get specular reflection vector
glint_angle_deg = dpr*spice.vsep(uvReflect,spice.vsub(toms_vec,surfPoint))
print('%s => %7.2f %s' % (linestrip,glint_angle_deg,'=Inputs[TOMS(alt,lon,lat),(Earth2Sun),Surface(lon,lat),UTC],GlintAngle',))
"""
- Longitude and Latitude in degrees
- Altitude in metres
[Altitude,Lon,Lat;Geodet] [Earth-Sun Unit Vec, ECEF] [SurfGeodLonLat] [UTC]
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 -10.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 -2.76 -25.307 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 2.76 -25.307 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 10.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 30.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 50.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 70.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 90.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 110.01 -26.768 2001-01-01T12:12:53
data: 766000 -10.743 -27.129 -.2577401 .8836004 -.3909224 130.01 -26.768 2001-01-01T12:12:53
Meta-kernel:
\begindata
KERNELS_TO_LOAD = (
'naif0011.tls'
'pck00010.tpc'
)
\begintext
"""