1 from polar_projection import *
   2 from read_asar import *
   3 from read_icesat import *
   4 from coord_transform import *
   5 from scipy import *
   6 
   7 def fit_freeboard_ASAR(filename1,filename2):
   8     """filename1: ASAR data file, filename2: freeboard data file
   9        creates new coordinate system defined by corners of ASAR image and selects freeboard values within ASAR image box
  10        returns an array containing normalized image coordinates and corresponding freeboard values:
  11        [x_coordinate, y_coordinate, freeboardheight(cm)]"""
  12     
  13     sgn=-1  #Antarctica
  14     ASAR=array(read_asar_corners(filename1))
  15     ASAR_p=zeros(8)
  16     for k in arange(0,7,2):       #computing polarstereographic coordinates
  17         ASAR_p[k:k+2]=mapll(ASAR[k],ASAR[k+1],sgn)
  18 
  19     A=coord_transformation(ASAR_p) #computing transformation matrix A for coordinate
  20                                    #transformation into image coordinates
  21  
  22     # reading freeboard data and computing geographic into polarstereographic coordinates
  23     ICESAT_p,fbh=read_icesat(filename2,sgn)    #fbh are measured freeboard heights in cm
  24 
  25     # calculating new coordinates for freeboard data
  26     x_neu=[]
  27     y_neu=[]
  28     for x,y in zip(ICESAT_p[0],ICESAT_p[1]):
  29         x_neu.append(dot(array([A[0,0],A[0,1]]),array([x,y]))+A[0,2])
  30         y_neu.append(dot(array([A[1,0],A[1,1]]),array([x,y]))+A[1,2])
  31     x_n=array(x_neu)
  32     y_n=array(y_neu)
  33     fbh_n=array(fbh)
  34 
  35     x_n_limited=clip(x_n,0.,1.)
  36     x_indices=nonzero(x_n==x_n_limited)
  37     x_xind=x_n[x_indices]
  38     y_xind=y_n[x_indices]
  39     fbh_xind=fbh_n[x_indices]
  40     
  41     y_n_limited=clip(y_xind,0.,1.)
  42     y_indices=nonzero(y_xind==y_n_limited)
  43     x_bild=x_xind[y_indices]
  44     y_bild=y_xind[y_indices]
  45     fbh_bild=fbh_xind[y_indices]
  46     
  47     x_y_fbh=array([x_bild,y_bild,fbh_bild])
  48 
  49     return x_y_fbh

   1 from scipy import linalg as la
   2 
   3 def coord_transformation(ASAR_p):
   4     # polarstereographic coordinate system
   5     y00,x00,y01,x01,y02,x02,y03,x03=int(ASAR_p[1]),int(ASAR_p[0]),int(ASAR_p[7]),int(ASAR_p[6]),int(ASAR_p[5]),int(ASAR_p[4]),int(ASAR_p[3]),int(ASAR_p[2])
   6     # new coordinate system with normalized coordinates  
   7     y10,x10,y11,x11,y12,x12,y13,x13=0,0,1,0,1,1,0,1
   8 
   9     # calculating transformation matrix:
  10     P0=array([[x00, x01, x02, x03],[y00,y01,y02,y03],[1.0,1.0,1.0,1.0]])
  11     P1=array([[x10, x11, x12, x13],[y10,y11,y12,y13],[1.0,1.0,1.0,1.0]])
  12 
  13     Faktor1=dot(P1,la.transpose(P0))
  14     Faktor2=la.inverse(dot(P0,la.transpose(P0)))
  15     A=dot(Faktor1,Faktor2)  # Transformation matrix
  16     return A

   1 # reading freeboard data
   2 
   3 import string
   4 from geo_polar import *
   5 from scipy import io
   6 
   7 def read_icesat(filename,sgn):
   8     data=io.read_array(filename)
   9     polar=mapll(data[:,1],data[:,0],sgn)
  10     fbh=data[:,2]
  11     return polar,fbh

   1 filename1='ASA_IMP_1PNDPA20060617_043346_000000162048_00362_22460_2136.N1'
   2 filename2='LonLatFre_1706_6.xyz'
   3 ergebnis=fit_freeboard_ASAR(filename1,filename2)