public float ParseGeoDataAtPoint(GeoTiffDictionary adjacentTiles, FileMetadata metadata, double lat, double lon, float lastElevation, IInterpolator interpolator)
{
float heightValue = 0;
try
{
IGeoTiff mainTiff = adjacentTiles[metadata];
//const double epsilon = (Double.Epsilon * 100);
float noData = metadata.NoDataValueFloat;
// precise position on the grid (with commas)
double ypos = (lat - metadata.StartLat) / metadata.pixelSizeY;
double xpos = (lon - metadata.StartLon) / metadata.pixelSizeX;
// If pure integers, then it's on the grid
float xInterpolationAmount = (float)xpos % 1;
float yInterpolationAmount = (float)ypos % 1;
bool xOnGrid = xInterpolationAmount == 0;
bool yOnGrid = yInterpolationAmount == 0;
// If xOnGrid and yOnGrid, we are on a grid intersection, and that's all
if (xOnGrid && yOnGrid)
{
int x = (int)Math.Round(xpos, 0);
int y = (int)Math.Round(ypos, 0);
var tile = FindTile(metadata, adjacentTiles, x, y, out x, out y);
heightValue = mainTiff.GetElevationAtPoint(tile, x, y);
}
else
{
int xCeiling = (int)Math.Ceiling(xpos);
int xFloor = (int)Math.Floor(xpos);
int yCeiling = (int)Math.Ceiling(ypos);
int yFloor = (int)Math.Floor(ypos);
// Get 4 grid nearest points (DEM grid corners)
// If not yOnGrid and not xOnGrid we are on grid horizontal line
// We need elevations for top, bottom, left and right grid points (along x axis and y axis)
float northWest = GetElevationAtPoint(metadata, adjacentTiles, xFloor, yFloor, NO_DATA_OUT);
float northEast = GetElevationAtPoint(metadata, adjacentTiles, xCeiling, yFloor, NO_DATA_OUT);
float southWest = GetElevationAtPoint(metadata, adjacentTiles, xFloor, yCeiling, NO_DATA_OUT);
float southEast = GetElevationAtPoint(metadata, adjacentTiles, xCeiling, yCeiling, NO_DATA_OUT);
float avgHeight = GetAverageExceptForNoDataValue(noData, NO_DATA_OUT, southWest, southEast, northWest, northEast);
if (northWest == noData)
{
northWest = avgHeight;
}
if (northEast == noData)
{
northEast = avgHeight;
}
if (southWest == noData)
{
southWest = avgHeight;
}
if (southEast == noData)
{
southEast = avgHeight;
}
heightValue = interpolator.Interpolate(southWest, southEast, northWest, northEast, xInterpolationAmount, yInterpolationAmount);
}
if (heightValue == NO_DATA_OUT)
{
heightValue = lastElevation;
}
}
catch (Exception e)
{
Trace.TraceError($"Error while getting elevation data : {e.Message}{Environment.NewLine}{e.ToString()}");
}
return(heightValue);
}
public bool IsPointInTile(FileMetadata tileMetadata, GeoPoint point)
{
return(IsPointInTile(tileMetadata.OriginLatitude, tileMetadata.OriginLongitude, point));
}