public static srtm.altresponce getAltitude(double lat, double lng, double zoom = 16)
{
if (index.Count == 0)
{
return(srtm.altresponce.Invalid);
}
var answer = new srtm.altresponce();
foreach (var DTEDdata in index)
{
if (DTEDdata.Area.Contains(lat, lng))
{
// add to cache
if (!cache.ContainsKey(DTEDdata.FileName))
{
short[,] altdata = new short[DTEDdata.width, DTEDdata.height];
using (var stream = File.OpenRead(DTEDdata.FileName))
{
stream.Seek(3428, SeekOrigin.Begin);
for (int b = 0; b < (DTEDdata.height); b++)
{
var buffer = new byte[DTEDdata.height * 2 + 12]; // header + checksum + data(shorts)
stream.Read(buffer, 0, buffer.Length);
if (buffer[0] == 0xaa)
{
int blockno = ((int)buffer[1] << 16) + ((int)buffer[2] << 8) + buffer[3];
int longcount = ((int)buffer[4] << 8) + buffer[5];
int latcount = ((int)buffer[6] << 8) + buffer[7];
for (int a = 0; a < DTEDdata.width; a++)
{
altdata[longcount, latcount + a] =
(short)(((int)buffer[8 + a * 2] << 8) + buffer[8 + a * 2 + 1]);
}
}
}
}
cache[DTEDdata.FileName] = altdata;
}
// get answer
var xf = map(lng, DTEDdata.Area.Left, DTEDdata.Area.Right - DTEDdata.xscale, 0, DTEDdata.width - 1);
var yf = map(lat, DTEDdata.Area.Bottom, DTEDdata.Area.Top - DTEDdata.yscale, 0, DTEDdata.height - 1);
int x_int = (int)xf;
double x_frac = xf - x_int;
int y_int = (int)yf;
double y_frac = yf - y_int;
double alt00 = GetAlt(DTEDdata.FileName, x_int, y_int);
double alt10 = GetAlt(DTEDdata.FileName, x_int + 1, y_int);
double alt01 = GetAlt(DTEDdata.FileName, x_int, y_int + 1);
double alt11 = GetAlt(DTEDdata.FileName, x_int + 1, y_int + 1);
double v1 = avg(alt00, alt10, x_frac);
double v2 = avg(alt01, alt11, x_frac);
double v = avg(v1, v2, y_frac);
if (v > -1000)
{
answer.currenttype = srtm.tiletype.valid;
}
answer.alt = v;
answer.altsource = "DTED";
return(answer);
}
}
return(srtm.altresponce.Invalid);
}
public static srtm.altresponce getAltitude(double lat, double lng, double zoom = 16)
{
if (index.Count == 0)
{
return(srtm.altresponce.Invalid);
}
var answer = new srtm.altresponce();
foreach (var geotiffdata in index)
{
if (geotiffdata.Area.Contains(lat, lng))
{
// add to cache
if (!cache.ContainsKey(geotiffdata.FileName) && geotiffdata.cacheable)
{
float[,] altdata = new float[geotiffdata.height, geotiffdata.width];
using (Tiff tiff = Tiff.Open(geotiffdata.FileName, "r"))
{
byte[] scanline = new byte[tiff.ScanlineSize()];
for (int row = 0; row < geotiffdata.height; row++)
{
tiff.ReadScanline(scanline, row);
for (int col = 0; col < geotiffdata.width; col++)
{
if (geotiffdata.bits == 16)
{
altdata[row, col] = (short)((scanline[col * 2 + 1] << 8) + scanline[col * 2]);
}
else if (geotiffdata.bits == 32)
{
altdata[row, col] = (float)BitConverter.ToSingle(scanline, col * 4);
}
}
}
}
cache[geotiffdata.FileName] = altdata;
}
// get answer
var xf = map(lat, geotiffdata.Area.Top, geotiffdata.Area.Bottom, 0, geotiffdata.height - 1);
var yf = map(lng, geotiffdata.Area.Left, geotiffdata.Area.Right, 0, geotiffdata.width - 1);
int x_int = (int)xf;
double x_frac = xf - x_int;
int y_int = (int)yf;
double y_frac = yf - y_int;
// y_int = (geotiffdata.height - 2) - y_int;
double alt00 = GetAlt(geotiffdata, x_int, y_int);
double alt10 = GetAlt(geotiffdata, x_int + 1, y_int);
double alt01 = GetAlt(geotiffdata, x_int, y_int + 1);
double alt11 = GetAlt(geotiffdata, x_int + 1, y_int + 1);
double v1 = avg(alt00, alt10, x_frac);
double v2 = avg(alt01, alt11, x_frac);
double v = avg(v1, v2, y_frac);
if (v > -1000)
{
answer.currenttype = srtm.tiletype.valid;
}
answer.alt = v;
answer.altsource = "GeoTiff";
return(answer);
}
}
return(srtm.altresponce.Invalid);
}