/**
* Fill 16 values of HGT near required coordinates
* can use HGTreaders near the current one
*/
private bool FillArray(HGTReader rdr, int row, int col, int xLeft, int yBottom)
{
int res = rdr.GetRes();
int minX = 0;
int minY = 0;
int maxX = 3;
int maxY = 3;
bool inside = true;
// check borders
if (xLeft == 0)
{
if (col <= 0)
{
return(false);
}
minX = 1;
inside = false;
}
else if (xLeft == res - 1)
{
if (col + 1 >= readers[0].Length)
{
return(false);
}
maxX = 2;
inside = false;
}
if (yBottom == 0)
{
if (row <= 0)
{
return(false);
}
minY = 1;
inside = false;
}
else if (yBottom == res - 1)
{
if (row + 1 >= readers.Length)
{
return(false);
}
maxY = 2;
inside = false;
}
// fill data from current reader
short h;
for (int x = minX; x <= maxX; x++)
{
for (int y = minY; y <= maxY; y++)
{
h = rdr.Ele(xLeft + x - 1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][y] = h;
maxhöhe = Math.Max(maxhöhe, h);
minhöhe = Math.Min(minhöhe, h);
}
}
if (inside) // no need to check borders again
{
return(true);
}
// fill data from adjacent readers, down and up
if (xLeft > 0 && xLeft < res - 1)
{
if (yBottom == 0)
{ // bottom edge
HGTReader rdrBB = PrepReader(res, row - 1, col);
if (rdrBB == null)
{
return(false);
}
for (int x = 0; x <= 3; x++)
{
h = rdrBB.Ele(xLeft + x - 1, res - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][0] = h;
}
}
else if (yBottom == res - 1)
{ // top edge
HGTReader rdrTT = PrepReader(res, row + 1, col);
if (rdrTT == null)
{
return(false);
}
for (int x = 0; x <= 3; x++)
{
h = rdrTT.Ele(xLeft + x - 1, 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][3] = h;
}
}
}
// fill data from adjacent readers, left and right
if (yBottom > 0 && yBottom < res - 1)
{
if (xLeft == 0)
{ // left edgge
HGTReader rdrLL = PrepReader(res, row, col - 1);
if (rdrLL == null)
{
return(false);
}
for (int y = 0; y <= 3; y++)
{
h = rdrLL.Ele(res - 1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[0][y] = h;
}
}
else if (xLeft == res - 1)
{ // right edge
HGTReader rdrRR = PrepReader(res, row, col + 1);
if (rdrRR == null)
{
return(false);
}
for (int y = 0; y <= 3; y++)
{
h = rdrRR.Ele(1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[3][y] = h;
}
}
}
// fill data from adjacent readers, corners
if (xLeft == 0)
{
if (yBottom == 0)
{ // left bottom corner
HGTReader rdrLL = PrepReader(res, row, col - 1);
if (rdrLL == null)
{
return(false);
}
for (int y = 1; y <= 3; y++)
{
h = rdrLL.Ele(res - 1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[0][y] = h;
}
HGTReader rdrBB = PrepReader(res, row - 1, col);
if (rdrBB == null)
{
return(false);
}
for (int x = 1; x <= 3; x++)
{
h = rdrBB.Ele(xLeft + x - 1, res - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][0] = h;
}
HGTReader rdrLB = PrepReader(res, row - 1, col - 1);
if (rdrLB == null)
{
return(false);
}
h = rdrLB.Ele(res - 1, res - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[0][0] = h;
}
else if (yBottom == res - 1)
{ // left top corner
HGTReader rdrLL = PrepReader(res, row, col - 1);
if (rdrLL == null)
{
return(false);
}
for (int y = 0; y <= 2; y++)
{
h = rdrLL.Ele(res - 1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[0][y] = h;
}
HGTReader rdrTT = PrepReader(res, row + 1, col);
if (rdrTT == null)
{
return(false);
}
for (int x = 1; x <= 3; x++)
{
h = rdrTT.Ele(xLeft + x - 1, 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][3] = h;
}
HGTReader rdrLT = PrepReader(res, row + 1, col - 1);
if (rdrLT == null)
{
return(false);
}
h = rdrLT.Ele(res - 1, 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[0][3] = h;
}
}
else if (xLeft == res - 1)
{
if (yBottom == 0)
{ // right bottom corner
HGTReader rdrRR = PrepReader(res, row, col + 1);
if (rdrRR == null)
{
return(false);
}
for (int y = 1; y <= 3; y++)
{
h = rdrRR.Ele(1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[3][y] = h;
}
HGTReader rdrBB = PrepReader(res, row - 1, col);
if (rdrBB == null)
{
return(false);
}
for (int x = 0; x <= 2; x++)
{
h = rdrBB.Ele(xLeft + x - 1, res - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][0] = h;
}
HGTReader rdrRB = PrepReader(res, row - 1, col + 1);
if (rdrRB == null)
{
return(false);
}
h = rdrRB.Ele(1, res - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[3][0] = h;
}
else if (yBottom == res - 1)
{ // right top corner
HGTReader rdrRR = PrepReader(res, row, col + 1);
if (rdrRR == null)
{
return(false);
}
for (int y = 0; y <= 2; y++)
{
h = rdrRR.Ele(1, yBottom + y - 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[3][y] = h;
}
HGTReader rdrTT = PrepReader(res, row + 1, col);
if (rdrTT == null)
{
return(false);
}
for (int x = 0; x <= 2; x++)
{
h = rdrTT.Ele(xLeft + x - 1, 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[x][3] = h;
}
HGTReader rdrRT = PrepReader(res, row + 1, col + 1);
if (rdrRT == null)
{
return(false);
}
h = rdrRT.Ele(1, 1);
if (h == HGTReader.UNDEF)
{
return(false);
}
eleArray[3][3] = h;
}
}
// all 16 values present
return(true);
}
protected double GetElevation(int lat32, int lon32)
{
int row = (int)((lat32 - minLat32) * FACTOR);
int col = (int)((lon32 - minLon32) * FACTOR);
HGTReader rdr = readers[row][col];
if (rdr == null)
{
// no reader : ocean or missing file
return(outsidePolygonHeight);
}
int res = rdr.GetRes();
rdr.PrepRead();
if (res <= 0)
{
return(0); // assumed to be an area in the ocean
}
lastRow = row;
double scale = res * FACTOR;
double y1 = (lat32 - minLat32) * scale - row * res;
double x1 = (lon32 - minLon32) * scale - col * res;
int xLeft = (int)x1;
int yBottom = (int)y1;
double qx = x1 - xLeft;
double qy = y1 - yBottom;
//statPoints++;
if (useComplexInterpolation)
{
// bicubic (Catmull-Rom) interpolation with 16 points
bool filled = FillArray(rdr, row, col, xLeft, yBottom);
if (filled)
{
h = BicubicInterpolation(eleArray, qx, qy);
//statBicubic++;
}
}
if (h == HGTReader.UNDEF || !useComplexInterpolation)
{
// use bilinear interpolation if bicubic not available
int xRight = xLeft + 1;
int yTop = yBottom + 1;
int hLT = rdr.Ele(xLeft, yTop);
maxhöhe = Math.Max(maxhöhe, hLT);
minhöhe = Math.Min(minhöhe, hLT);
int hRT = rdr.Ele(xRight, yTop);
maxhöhe = Math.Max(maxhöhe, hRT);
minhöhe = Math.Min(minhöhe, hRT);
int hLB = rdr.Ele(xLeft, yBottom);
maxhöhe = Math.Max(maxhöhe, hLB);
minhöhe = Math.Min(minhöhe, hLB);
int hRB = rdr.Ele(xRight, yBottom);
maxhöhe = Math.Max(maxhöhe, hRB);
minhöhe = Math.Min(minhöhe, hRB);
h = InterpolatedHeight(qx, qy, hLT, hRT, hRB, hLB);
//statBilinear++;
//if (h == HGTReader.UNDEF) statVoid++;
}
//if (h == HGTReader.UNDEF && log.isLoggable(Level.WARNING))
//{
// double lon = lon32 * FACTOR;
// double lat = lat32 * FACTOR;
// Coord c = new Coord(lat, lon);
// log.warn("height interpolation returns void at", c.toDegreeString());
//}
return(h);
}