[2286] | 1 | """ |
---|
| 2 | Author: John Jakeman |
---|
| 3 | Created: 12/12/2005 |
---|
| 4 | Program used to convert a commer seperated .xya file consiting of |
---|
| 5 | X and Y corrdinates in degrees and an elevation in meters into an .xya file |
---|
| 6 | in which all quantities are measured in meters |
---|
| 7 | """ |
---|
| 8 | |
---|
| 9 | def convert_latlon_to_xycoords(lat,longt,origin): |
---|
| 10 | |
---|
| 11 | from math import cos, pi |
---|
| 12 | r_earth = 6.378135E+06 |
---|
| 13 | |
---|
| 14 | lat_origin,long_origin = origin |
---|
| 15 | # Evalulates distance in X-direction from origin for points in |
---|
| 16 | # Western Hemispehere |
---|
| 17 | if lat < 0: |
---|
| 18 | X = (360.0+lat-lat_origin)/360.0*abs(cos(longt*pi/180.0))*r_earth*2.0*pi |
---|
| 19 | |
---|
| 20 | elif lat < lat_origin: # Only needed when lat_origin > 0 |
---|
| 21 | X = (360.0-lat-lat_origin)/360.0*abs(cos(longt*pi/180.0))*r_earth*2.0*pi |
---|
| 22 | |
---|
| 23 | # Evaluates distance from origin in X-direction for points in |
---|
| 24 | # Eastern Hemisphere |
---|
| 25 | else: |
---|
| 26 | X = (lat-lat_origin)/360.0*abs(cos(longt*pi/180.0))*r_earth*2.0*pi |
---|
| 27 | # Calulates distance in Y-direction from a point to origin |
---|
| 28 | Y = abs((longt-long_origin)/360.0*2*pi*r_earth) |
---|
| 29 | if Y < 0 : |
---|
| 30 | Y = 2*pi*r_earth + Y |
---|
| 31 | |
---|
| 32 | return [X,Y] |
---|
| 33 | |
---|
| 34 | """ |
---|
| 35 | from Numeric import array, zeros, Float, asarray |
---|
| 36 | |
---|
| 37 | # Open .xya file to be converted |
---|
| 38 | filename = 'cairns_degrees.xya' |
---|
| 39 | fid = open(filename) |
---|
| 40 | |
---|
| 41 | # Skip first line |
---|
| 42 | line = fid.readline() |
---|
| 43 | |
---|
| 44 | # Read remaining lines |
---|
| 45 | lines = fid.readlines() |
---|
| 46 | fid.close() |
---|
| 47 | |
---|
| 48 | # Origin of cartesian system is the point (lat_origin, long_origin) |
---|
| 49 | lat_origin = 145.0 |
---|
| 50 | long_origin = -24.0 |
---|
| 51 | |
---|
| 52 | origin = lat_origin, long_origin |
---|
| 53 | |
---|
| 54 | # fields[0]: latitude |
---|
| 55 | # fields[1]: longitude |
---|
| 56 | # fields[2]: elevation |
---|
| 57 | |
---|
| 58 | # Open .xya file to be used to store new coordinates in meters |
---|
| 59 | filename = 'cairns_test.xya' |
---|
| 60 | fid = open(filename, "w") |
---|
| 61 | fid.write('elevation\n') |
---|
| 62 | |
---|
| 63 | |
---|
| 64 | for i, line in enumerate(lines): |
---|
| 65 | fields = line.split(',') |
---|
| 66 | |
---|
| 67 | X,Y = convert_latlon_to_xycoords(float(fields[0]),float(fields[1]),origin) |
---|
| 68 | |
---|
| 69 | # Write X and Y corrdinates and corresponding elevation to .xya file |
---|
| 70 | fid.write(repr(X) + ', ') |
---|
| 71 | fid.write(repr(Y) + ', ') |
---|
| 72 | fid.write(fields[2]) |
---|
| 73 | |
---|
| 74 | fid.close() |
---|
| 75 | """ |
---|