tim/prune/function/srtm/gen/GenerateTileLookup.java

   1 package tim.prune.function.srtm.gen;
   2
   3 import java.io.BufferedReader;
   4 import java.io.File;
   5 import java.io.FileOutputStream;
   6 import java.io.FileReader;
   7
   8 /**
   9  * Class used to generate a lookup file to find the URLs of SRTM tiles.
  10  * The tiles are split into directories for each continent, so we need some way
  11  * of going from coordinates to directories.
  12  * This class reads the directory listings from the files tiles1.txt, tiles2.txt etc
  13  * and combines the result into a binary array
  14  */
  15 public class GenerateTileLookup
  16 {
  17
  18         /**
  19          * Main method for generating the array
  20          * @param args ignored
  21          */
  22         public static void main(String[] args)
  23         {
  24                 System.out.println("Generate tile lookup");
  25                 byte[] lookup = new byte[360 * 120]; // +/- 180 degrees longitude, +/- 60 degrees latitude
  26                 for (int f=1; f<= 6; f++)
  27                 {
  28                         try
  29                         {
  30                                 BufferedReader r = new BufferedReader(new FileReader(new File("tim/prune/function/srtm/gen/tiles" + f + ".txt")));
  31                                 String line = r.readLine();
  32                                 System.out.println("Read continent: '" + line + "'");
  33                                 while ((line = r.readLine()) != null) {
  34                                         if (line.length() == 7)
  35                                         {
  36                                                 boolean north = (line.charAt(0) == 'N');
  37                                                 int lat = Integer.parseInt(line.substring(1, 3));
  38                                                 if (!north) {lat = -lat;}
  39                                                 boolean east = (line.charAt(3) == 'E');
  40                                                 int lon = Integer.parseInt(line.substring(4));
  41                                                 if (!east) {lon = -lon;}
  42                                                 // Store in lookup
  43                                                 int arrindex = (lat+59)*360 + (lon+180);
  44                                                 lookup[arrindex] = (byte) f;
  45                                         }
  46                                 }
  47                         }
  48                         catch (Exception e) {
  49                                 e.printStackTrace();
  50                         }
  51                 }
  52                 // Now f should be populated
  53                 StringBuilder b = new StringBuilder();
  54                 for (int l=-180; l<180; l++) {
  55                         int i = 59 * 360 + (l+180);
  56                         b.append("" + lookup[i]);
  57                 }
  58                 System.out.println("equator: " + b.toString());
  59
  60                 // Write bytes to file
  61                 try {
  62                         FileOutputStream out = new FileOutputStream(new File("srtmtiles.dat"));
  63                         out.write(lookup);
  64                         out.close();
  65                 }
  66                 catch (Exception e) {
  67                         e.printStackTrace();
  68                 }
  69         }
  70 }