Sanity Check and Filtering
First step of the data processing chain.
Last updated
First step of the data processing chain.
Last updated
Field boundaries are determined using either the alpha algorithm (alphashape) with the alpha parameter equal to the number of coordinates:
import alphashape
alpha = len(position)
alpha_shape = alphashape.alphashape(points, alpha)or, if the alpha shape algorithm is not successful, the ConvexHull algorithm:
from scipy.spatial import ConvexHull
hull = ConvexHull(points)
indices = hull.verticesThe dataset is discarded if the area inside the field boundaries is less than 200 square metres.
The dataset is discarded if the total number of usable data points in the data set is less than 100.
The median value in each spectrum (HH, VV, HV, and VH) is calculated.
Total power, polarized power, and unpolarized power are calculated:
The data point is discarded if the total power for an integration exceeds 400 Kelvin or is less than 50 Kelvin.
temp_tot = (0.5 * (data_hh2 + data_vv2))
temp_q = 1.0 * (0.5 * (data_hh2 - data_vv2))
temp_pol = np.sqrt(data_u * data_u + temp_q * temp_q + data_v * data_v)
temp_unpol = temp_tot - temp_pol