/// <summary>
/// Finds all intersections between given segment and DEM grid
/// </summary>
/// <param name="startLon">Segment start longitude</param>
/// <param name="startLat">Segment start latitude</param>
/// <param name="endLon">Segment end longitude</param>
/// <param name="endLat">Segment end latitude</param>
/// <param name="segTiles">Metadata files <see cref="GeoTiffService.GetCoveringFiles"/> to see how to get them relative to segment geometry</param>
/// <param name="returnStartPoint">If true, the segment starting point will be returned. Useful when processing a line segment by segment.</param>
/// <param name="returnEndPoind">If true, the segment end point will be returned. Useful when processing a line segment by segment.</param>
/// <returns></returns>
public List <GeoPoint> FindSegmentIntersections(double startLon, double startLat, double endLon, double endLat, List <FileMetadata> segTiles, bool returnStartPoint, bool returnEndPoind)
{
List <GeoPoint> segmentPointsWithDEMPoints;
// Find intersections with north/south lines,
// starting form segment western point to easternmost point
GeoPoint westernSegPoint = startLon < endLon ? new GeoPoint(startLat, startLon) : new GeoPoint(endLat, endLon);
GeoPoint easternSegPoint = startLon > endLon ? new GeoPoint(startLat, startLon) : new GeoPoint(endLat, endLon);
GeoSegment inputSegment = new GeoSegment(westernSegPoint, easternSegPoint);
if (segTiles.Any())
{
int estimatedCapacity = (segTiles.Select(t => t.OriginLongitude).Distinct().Count() // num horizontal tiles * width
* segTiles.First().Width)
+ (segTiles.Select(t => t.OriginLatitude).Distinct().Count() // num vertical tiles * height
* segTiles.First().Height);
segmentPointsWithDEMPoints = new List <GeoPoint>(estimatedCapacity);
bool yAxisDown = segTiles.First().pixelSizeY < 0;
if (yAxisDown == false)
{
throw new NotImplementedException("DEM with y axis upwards not supported.");
}
foreach (GeoSegment demSegment in this.GetDEMNorthSouthLines(segTiles, westernSegPoint, easternSegPoint))
{
GeoPoint intersectionPoint = null;
if (GeometryService.LineLineIntersection(out intersectionPoint, inputSegment, demSegment))
{
segmentPointsWithDEMPoints.Add(intersectionPoint);
}
}
// Find intersections with west/east lines,
// starting form segment northernmost point to southernmost point
GeoPoint northernSegPoint = startLat > endLat ? new GeoPoint(startLat, startLon) : new GeoPoint(endLat, endLon);
GeoPoint southernSegPoint = startLat < endLat ? new GeoPoint(startLat, startLon) : new GeoPoint(endLat, endLon);
inputSegment = new GeoSegment(northernSegPoint, southernSegPoint);
foreach (GeoSegment demSegment in this.GetDEMWestEastLines(segTiles, northernSegPoint, southernSegPoint))
{
GeoPoint intersectionPoint = null;
if (GeometryService.LineLineIntersection(out intersectionPoint, inputSegment, demSegment))
{
segmentPointsWithDEMPoints.Add(intersectionPoint);
}
}
}
else
{
// No DEM coverage
segmentPointsWithDEMPoints = new List <GeoPoint>(2);
}
// add start and/or end point
if (returnStartPoint)
{
segmentPointsWithDEMPoints.Add(inputSegment.Start);
}
if (returnEndPoind)
{
segmentPointsWithDEMPoints.Add(inputSegment.End);
}
// sort points in segment order
//
segmentPointsWithDEMPoints.Sort(new DistanceFromPointComparer(new GeoPoint(startLat, startLon)));
return(segmentPointsWithDEMPoints);
}
public static double GetLength(string lineWKT)
{
return(GeometryService.ParseWKTAsGeography(lineWKT).STLength().Value);
}
