def frToTEC(self, date, corners, lookAngle, lookDirection, fc):
"""
Given a list of geodetic coordinates, a list of lookAngles and a list of lookDirections,
calculate the average value of the B-field in the radar line-of-sight. Look angles are
calculated in degrees from the nadir and look directions are calculated in degrees from
the perpendicular to the flight direction.
@param date (\a datetime.datetime) the date on which to calculate the B-field
@param corners (\a list) a list of Location.Coordinate objects specifying the corners of the radar image
@param lookAngle (\a list) a list of the look angles (in degrees) to each corner of the radar image
@param lookDirection (\a list) a list of the look directions (in degrees) to each corner of the radar image
@param fc (\a float) the radar carrier frequency in Hz
@return (\a float) the mean value of the B-field in the look direction of the radar in gauss
"""
kdotb = []
# Calculate the integrated B vector for each of the four corners of the interferogram
# Need to get the date from any of the Frame objects associated with one of the polarities
for i, coordinate in enumerate(corners):
k = self._calculateLookVector(lookAngle[i], lookDirection[i])
kdotb.append(self._integrateBVector(date, coordinate, k))
# Use this value to convert from Faraday rotation to TEC
meankdotb = MM.mean(kdotb)
self.logger.info("Creating TEC Map")
self._scaleFRToTEC(meankdotb, fc)
# Create a resource file for the TEC output file
rsc = ResourceFile(self.tecOutput + '.rsc')
rsc.write('WIDTH', self.samples)
rsc.write('FILE_LENGTH', self.lines)
rsc.write('MEAN_K_DOT_B', meankdotb)
rsc.write('LOOK_DIRECTION', lookDirection[0])
for i in range(len(corners)):
lattag = 'LAT_CORNER_' + str((i + 1))
lontag = 'LON_CORNER_' + str((i + 1))
looktag = 'LOOK_ANGLE_' + str((i + 1))
rsc.write(lattag, corners[i].getLatitude())
rsc.write(lontag, corners[i].getLongitude())
rsc.write(looktag, lookAngle[i])
rsc.close()
return meankdotb
def _integrateBVector(self, date, coordinate, k):
"""
Integrate the B-field estimates through the ionosphere at the specified date and location
@param date (\a datetime.datetime) date at which to calculate the B-field
@param coordinate (\a isceobj.Location.Coordinate) the coordinate at which to calculate the B-field.
@param k (\a list) the look vector of the radar
@return (\a float) the integrated value of the B-field at the specified date and location in gauss
"""
kdotb = []
n_altitude = int((self.top - self.bottom) / self.step) + 1
altitude = [self.bottom + i * self.step for i in range(n_altitude)]
for h in altitude:
coordinate.setHeight(h)
bvector = self._calculateBVector(date, coordinate)
kdotb.append(MM.dotProduct(k, bvector))
meankdotb = MM.mean(kdotb)
return meankdotb
def testMean(self):
ans = 2
mean = MM.mean(self.V)
self.assertAlmostEquals(mean, ans)
