@Override
public double getEle(double lat, double lon) {
lat = (int) (lat * precision) / precision;
lon = (int) (lon * precision) / precision;
int intKey = calcIntKey(lat, lon);
HeightTile demProvider = cacheData.get(intKey);
if (demProvider == null) {
if (!cacheDir.exists()) cacheDir.mkdirs();
String fileDetails = getFileString(lat, lon);
if (fileDetails == null) return 0;
int minLat = down(lat);
int minLon = down(lon);
demProvider = new HeightTile(minLat, minLon, WIDTH, precision);
cacheData.put(intKey, demProvider);
try {
String zippedURL = baseUrl + "/" + fileDetails + "hgt.zip";
File file = new File(cacheDir, new File(zippedURL).getName());
InputStream is;
// get zip file if not already in cacheDir - unzip later and in-memory only!
if (!file.exists()) {
for (int i = 0; i < 2; i++) {
try {
downloader.downloadFile(zippedURL, file.getAbsolutePath());
break;
} catch (FileNotFoundException ex) {
// now try with point if mirror is used
zippedURL = baseUrl + "/" + fileDetails + ".hgt.zip";
continue;
}
}
}
is = new FileInputStream(file);
ZipInputStream zis = new ZipInputStream(is);
zis.getNextEntry();
BufferedInputStream buff = new BufferedInputStream(zis);
byte[] bytes = new byte[2 * WIDTH * WIDTH];
DataAccess heights = getDirectory().find("dem" + intKey);
heights.create(bytes.length);
demProvider.setHeights(heights);
int len;
while ((len = buff.read(bytes)) > 0) {
for (int bytePos = 0; bytePos < len; bytePos += 2) {
short val = BIT_UTIL.toShort(bytes, bytePos);
if (val < -1000 || val > 10000) {
// TODO fill unassigned gaps with neighbor values -> flood fill algorithm !
// -> calculate mean with an associated weight of how long the distance to the
// neighbor is
// throw new IllegalStateException("Invalid height value "
// + val
// + ", y:" + bytePos / WIDTH + ", x:" + (WIDTH -
// bytePos % WIDTH));
val = Short.MIN_VALUE;
}
heights.setShort(bytePos, val);
}
}
// demProvider.toImage(file.getName() + ".png");
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
short val = demProvider.getHeight(lat, lon);
if (val == Short.MIN_VALUE) return Double.NaN;
return val;
}
