/// <summary>
/// Generates an index file by listing all available SRTM cells on the FTP site.
/// </summary>
public void Generate()
{
activityLogger.Log(ActivityLogLevel.Verbose, "Downloading data for SRTM index generation");
for (SrtmContinentalRegion continentalRegion = (SrtmContinentalRegion)(SrtmContinentalRegion.None + 1);
continentalRegion < SrtmContinentalRegion.End;
continentalRegion++)
{
string region = continentalRegion.ToString();
string url = srtmSource + region + "/";
WebRequest request = WebRequest.Create(new System.Uri(url));
WebResponse response = request.GetResponse();
// Get the stream containing content returned by the server.
Stream dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd();
MatchCollection matches = Regex.Matches(responseFromServer, fileNamePattern, RegexOptions.IgnoreCase);
// Process each match.
foreach (Match match in matches)
{
GroupCollection groups = match.Groups;
string filename = groups[1].Value.Trim();
if (filename.Length == 0)
{
continue;
}
Srtm3Cell srtm3Cell = Srtm3Cell.CreateSrtm3Cell(filename, false);
SetValueForCell(srtm3Cell.CellLon, srtm3Cell.CellLat, (int)continentalRegion);
}
// Cleanup the streams and the response.
reader.Close();
dataStream.Close();
response.Close();
}
}
public IDigitalElevationModel LoadDemForArea(Bounds2 bounds)
{
// make sure the cache directory exists
if (false == Directory.Exists(srtm3CachePath))
{
Directory.CreateDirectory(srtm3CachePath);
}
// first create a list of geographicals cells which constitute the specified area
IDictionary <int, Srtm3Cell> cellsToUse = new Dictionary <int, Srtm3Cell> ();
for (int lat = CalculateCellDegrees(bounds.MinY); lat <= CalculateCellDegrees(bounds.MaxY); lat++)
{
for (int lng = CalculateCellDegrees(bounds.MinX); lng <= CalculateCellDegrees(bounds.MaxX); lng++)
{
Srtm3Cell cell = new Srtm3Cell((Int16)lng, (Int16)lat);
cellsToUse.Add(Srtm3Cell.CalculateCellKey(cell), cell);
}
}
// then fetch a list of already downloaded cells
IDictionary <int, Srtm3Cell> cachedCells = FetchCachedCellsList();
try
{
foreach (Srtm3Cell cell in cellsToUse.Values)
{
// if it is not cached...
if (false == cachedCells.ContainsKey(Srtm3Cell.CalculateCellKey(cell)))
{
// find the right subdirectory
SrtmContinentalRegion continentalRegion = (SrtmContinentalRegion)index.GetValueForCell(cell.CellLon, cell.CellLat);
if (continentalRegion == SrtmContinentalRegion.None)
{
// the cell does not exist in the index, it is probably an ocean cell
// add an empty cell to the cache and go to the next cell
cachedCells.Add(Srtm3Cell.CalculateCellKey(cell), cell);
continue;
}
string filename = string.Format(System.Globalization.CultureInfo.InvariantCulture, "{0}.zip", cell.CellFileName);
string url = srtmSource + continentalRegion.ToString() + "/" + filename;
string localFilename = Path.Combine(srtm3CachePath, filename);
this.activityLogger.Log(ActivityLogLevel.Verbose, "Downloading SRTM cell " + cell.CellFileName);
WebRequest request = WebRequest.Create(new System.Uri(url));
WebResponse response = request.GetResponse();
// Get the stream containing content returned by the server.
Stream dataStream = response.GetResponseStream();
FileStream fileStream = new FileStream(localFilename, FileMode.OpenOrCreate);
//Download in chuncks
byte[] buffer = new byte[1024];
int bytesRead;
while ((bytesRead = dataStream.Read(buffer, 0, buffer.Length)) > 0)
{
fileStream.Write(buffer, 0, bytesRead);
}
long receivedLength = fileStream.Length;
fileStream.Close();
dataStream.Close();
response.Close();
// Check if the download is complete.
if (response.ContentLength != -1 && response.ContentLength > receivedLength)
{
File.Delete(localFilename);
throw new WebException("Download incomplete (content length mismatch).", null, WebExceptionStatus.ReceiveFailure, response);
}
// unzip it and delete the zip file
FastZip zip = new FastZip();
zip.ExtractZip(localFilename, srtm3CachePath, null);
File.Delete(localFilename);
}
// now load it
cell.LoadFromCache(srtm3CachePath);
}
}
finally
{
}
// create elevation data
int west, south, east, north;
west = Srtm3Storage.CalculateCellPosition(bounds.MinX);
south = Srtm3Storage.CalculateCellPosition(bounds.MinY);
east = Srtm3Storage.CalculateCellPosition(bounds.MaxX);
north = Srtm3Storage.CalculateCellPosition(bounds.MaxY);
int width = east - west + 1;
int height = north - south + 1;
long requiredBytes = width * height * 2L;
int loadCounter = 1;
RasterDigitalElevationModelFactory factory = new RasterDigitalElevationModelFactory(1200, 1200, west, south, width, height);
factory.ActivityLogger = activityLogger;
RasterDigitalElevationModelBase dem = factory.CreateSupportedModel();
if (dem == null)
{
throw new PlatformNotSupportedException("No suitable location for the DEM found.");
}
// and fill the DEM with each cell points
foreach (Srtm3Cell cell in cellsToUse.Values)
{
this.activityLogger.LogFormat(ActivityLogLevel.Normal,
"Loading cell {0} of {1} into DEM", loadCounter++, cellsToUse.Values.Count);
dem.CopyElevationPointsFrom(cell);
}
return(dem);
}
