public List <GeoPoint> GetLineGeometryElevation(SqlGeometry lineStringGeometry, DEMDataSet dataSet, InterpolationMode interpolationMode = InterpolationMode.Bilinear)
{
if (lineStringGeometry == null || lineStringGeometry.IsNull)
{
return(null);
}
if (lineStringGeometry.STGeometryType().Value != "LineString")
{
throw new Exception("Geometry must be a linestring");
}
if (lineStringGeometry.STSrid.Value != 4326)
{
throw new Exception("Geometry SRID must be set to 4326 (WGS 84)");
}
BoundingBox bbox = lineStringGeometry.GetBoundingBox();
List <FileMetadata> tiles = this.GetCoveringFiles(bbox, dataSet);
// Init interpolator
IInterpolator interpolator = GetInterpolator(interpolationMode);
double lengthMeters = lineStringGeometry.STLength().Value;
int demResolution = dataSet.ResolutionMeters;
int totalCapacity = 2 * (int)(lengthMeters / demResolution);
List <GeoPoint> geoPoints = new List <GeoPoint>(totalCapacity);
using (GeoTiffDictionary adjacentGeoTiffs = new GeoTiffDictionary())
{
bool isFirstSegment = true; // used to return first point only for first segments, for all other segments last point will be returned
foreach (SqlGeometry segment in lineStringGeometry.Segments())
{
List <FileMetadata> segTiles = this.GetCoveringFiles(segment.GetBoundingBox(), dataSet, tiles);
// Find all intersection with segment and DEM grid
List <GeoPoint> intersections = this.FindSegmentIntersections(segment.STStartPoint().STX.Value
, segment.STStartPoint().STY.Value
, segment.STEndPoint().STX.Value
, segment.STEndPoint().STY.Value
, segTiles
, isFirstSegment
, true);
// Get elevation for each point
this.GetElevationData(ref intersections, adjacentGeoTiffs, segTiles, interpolator);
// Add to output list
geoPoints.AddRange(intersections);
isFirstSegment = false;
}
//Debug.WriteLine(adjacentGeoTiffs.Count);
} // Ensures all geotifs are properly closed
return(geoPoints);
}
/// <summary>
/// Fill altitudes for each GeoPoint provided, opening as few GeoTiffs as possible
/// </summary>
/// <param name="intersections"></param>
/// <param name="segTiles"></param>
public void GetElevationData(ref List <GeoPoint> intersections, GeoTiffDictionary adjacentGeoTiffs, List <FileMetadata> segTiles, IInterpolator interpolator)
{
// Group by tiff file for sequential and faster access
var pointsByTileQuery = from point in intersections
let pointTile = new
{
Point = point,
Tile = segTiles.FirstOrDefault(t => this.IsPointInTile(t, point)),
AdjacentTiles = segTiles.Where(t => this.IsPointInAdjacentTile(t, point)).ToList()
}
group pointTile by pointTile.Tile into pointsByTile
where pointsByTile.Key != null
select pointsByTile;
try
{
float lastElevation = 0;
// To interpolate well points close to tile edges, we need all adjacent tiles
//using (GeoTiffDictionary adjacentGeoTiffs = new GeoTiffDictionary())
//{
// For each group (key = tile, values = points within this tile)
// TIP: test use of Parallel (warning : a lot of files may be opened at the same time)
foreach (var tilePoints in pointsByTileQuery)
{
// Get the tile
FileMetadata mainTile = tilePoints.Key;
// We open geotiffs first, then we iterate
PopulateGeoTiffDictionary(adjacentGeoTiffs, mainTile, _IGeoTiffService, tilePoints.SelectMany(tp => tp.AdjacentTiles));
foreach (var pointile in tilePoints)
{
GeoPoint current = pointile.Point;
lastElevation = this.ParseGeoDataAtPoint(adjacentGeoTiffs, mainTile, current.Latitude, current.Longitude, lastElevation, interpolator);
current.Elevation = lastElevation;
}
//adjacentGeoTiffs.Clear();
}
}
//}
catch (Exception e)
{
Trace.TraceError($"Error while getting elevation data : {e.Message}{Environment.NewLine}{e.ToString()}");
}
}
private void PopulateGeoTiffDictionary(GeoTiffDictionary dictionary, FileMetadata mainTile, IGeoTiffService geoTiffService, IEnumerable <FileMetadata> fileMetadataList)
{
// Add main tile
if (!dictionary.ContainsKey(mainTile))
{
dictionary[mainTile] = geoTiffService.OpenFile(mainTile.Filename);
}
foreach (var fileMetadata in fileMetadataList)
{
if (!dictionary.ContainsKey(fileMetadata))
{
dictionary[fileMetadata] = geoTiffService.OpenFile(fileMetadata.Filename);
}
}
}
private float GetElevationAtPoint(FileMetadata mainTile, GeoTiffDictionary tiles, int x, int y, float nullValue)
{
int xRemap, yRemap;
FileMetadata goodTile = FindTile(mainTile, tiles, x, y, out xRemap, out yRemap);
if (goodTile == null)
{
return(nullValue);
}
if (tiles.ContainsKey(goodTile))
{
return(tiles[goodTile].ParseGeoDataAtPoint(goodTile, xRemap, yRemap));
}
else
{
throw new Exception("Tile not found. Should not happen.");
}
}
private FileMetadata FindTile(FileMetadata mainTile, GeoTiffDictionary tiles, int x, int y, out int newX, out int newY)
{
int xTileOffset = x < 0 ? -1 : x >= mainTile.Width ? 1 : 0;
int yTileOffset = y < 0 ? -1 : y >= mainTile.Height ? 1 : 0;
if (xTileOffset == 0 && yTileOffset == 0)
{
newX = x;
newY = y;
return(mainTile);
}
else
{
int yScale = Math.Sign(mainTile.pixelSizeY);
FileMetadata tile = tiles.Keys.FirstOrDefault(
t => t.OriginLatitude == mainTile.OriginLatitude + yScale * yTileOffset &&
t.OriginLongitude == mainTile.OriginLongitude + xTileOffset);
newX = xTileOffset > 0 ? x % mainTile.Width : (mainTile.Width + x) % mainTile.Width;
newY = yTileOffset < 0 ? (mainTile.Height + y) % mainTile.Height : y % mainTile.Height;
return(tile);
}
}
public GeoPoint GetPointElevation(double lat, double lon, DEMDataSet dataSet, InterpolationMode interpolationMode = InterpolationMode.Bilinear)
{
GeoPoint geoPoint = new GeoPoint(lat, lon);
List <FileMetadata> tiles = this.GetCoveringFiles(lat, lon, dataSet);
// Init interpolator
IInterpolator interpolator = GetInterpolator(interpolationMode);
List <GeoPoint> geoPoints = new List <GeoPoint>();
using (GeoTiffDictionary adjacentGeoTiffs = new GeoTiffDictionary())
{
PopulateGeoTiffDictionary(adjacentGeoTiffs, tiles.First(), _IGeoTiffService, tiles);
geoPoint.Elevation = ParseGeoDataAtPoint(adjacentGeoTiffs, tiles.First(), lat, lon, 0, interpolator);
//Debug.WriteLine(adjacentGeoTiffs.Count);
} // Ensures all geotifs are properly closed
return(geoPoint);
}
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.ParseGeoDataAtPoint(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);
}
