private IEnumerable <GeoSegment> GetDEMWestEastLines(List <FileMetadata> segTiles, GeoPoint northernSegPoint, GeoPoint southernSegPoint)
{
// Get the first north west tile and last south east tile.
// The lines are bounded by those tiles
foreach (var tilesByY in segTiles.GroupBy(t => t.StartLat).OrderByDescending(g => g.Key))
{
List <FileMetadata> WETilesOrdered = tilesByY.OrderBy(t => t.StartLon).ToList();
FileMetadata left = WETilesOrdered.First();
FileMetadata right = WETilesOrdered.Last();
GeoPoint curPoint = new GeoPoint(left.StartLat, left.StartLon);
// Y Index in tile coords
int curIndex = (int)Math.Ceiling((left.StartLat - curPoint.Latitude) / left.PixelScaleY);
while (IsPointInTile(left, curPoint))
{
if (curIndex >= left.Height)
{
break;
}
curPoint.Latitude = left.StartLat + (left.pixelSizeY * curIndex);
if (curPoint.Latitude < southernSegPoint.Latitude)
{
break;
}
GeoSegment line = new GeoSegment(new GeoPoint(curPoint.Latitude, left.OriginLongitude), new GeoPoint(curPoint.Latitude, right.EndLongitude));
curIndex++;
yield return(line);
}
}
}
public bool IsPointInTile(FileMetadata tileMetadata, GeoPoint point)
{
return(IsPointInTile(tileMetadata, point.Latitude, point.Longitude));
}
/// <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="IElevationService.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>
private 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))
{
if (GeometryService.LineLineIntersection(out GeoPoint 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))
{
if (GeometryService.LineLineIntersection(out GeoPoint 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);
}
private IEnumerable <GeoSegment> GetDEMNorthSouthLines(List <FileMetadata> segTiles, GeoPoint westernSegPoint, GeoPoint easternSegPoint)
{
// Get the first north west tile and last south east tile.
// The lines are bounded by those tiles
foreach (var tilesByX in segTiles.GroupBy(t => t.StartLon).OrderBy(g => g.Key))
{
List <FileMetadata> NSTilesOrdered = tilesByX.OrderByDescending(t => t.StartLat).ToList();
FileMetadata top = NSTilesOrdered.First();
FileMetadata bottom = NSTilesOrdered.Last();
// TIP: can optimize here starting with min(westernSegPoint, startlon) but careful !
GeoPoint curPoint = new GeoPoint(top.StartLat, top.StartLon);
// X Index in tile coords
int curIndex = (int)Math.Ceiling((curPoint.Longitude - top.StartLon) / top.PixelScaleX);
while (IsPointInTile(top, curPoint))
{
if (curIndex >= top.Width)
{
break;
}
curPoint.Longitude = top.StartLon + (top.pixelSizeX * curIndex);
if (curPoint.Longitude > easternSegPoint.Longitude)
{
break;
}
GeoSegment line = new GeoSegment(new GeoPoint(top.OriginLatitude, curPoint.Longitude), new GeoPoint(bottom.EndLatitude, curPoint.Longitude));
curIndex++;
yield return(line);
}
}
}
private IEnumerable <GeoSegment> GetDEMNorthSouthLines(List <FileMetadata> segTiles, GeoPoint westernSegPoint, GeoPoint easternSegPoint, double registrationOffsetPx)
{
// Get the first north west tile and last south east tile.
// The lines are bounded by those tiles
foreach (var tilesByX in segTiles.GroupBy(t => t.DataStartLon).OrderBy(g => g.Key))
{
List <FileMetadata> NSTilesOrdered = tilesByX.OrderByDescending(t => t.DataStartLat).ToList();
FileMetadata top = NSTilesOrdered.First();
FileMetadata bottom = NSTilesOrdered.Last();
// TIP: can optimize here starting with min(westernSegPoint, startlon) but careful !
GeoPoint curPoint = new GeoPoint(top.DataStartLat, top.DataStartLon);
// X Index in tile coords
int curIndex = (int)Math.Ceiling((curPoint.Longitude - top.PhysicalStartLon) / top.PixelScaleX - registrationOffsetPx);
// For cell registered datasets, DataStart is not matching the start data point. Start data point is at cell center (0.5 pixel off)
double startLon = top.FileFormat.Registration == DEMFileRegistrationMode.Cell
? top.DataStartLon + top.PixelScaleX / 2d
: top.DataStartLon;
while (IsPointInTile(top, curPoint))
{
if (curIndex >= top.Width)
{
break;
}
curPoint.Longitude = startLon + (top.pixelSizeX * curIndex);
if (curPoint.Longitude > easternSegPoint.Longitude)
{
break;
}
GeoSegment line = new GeoSegment(new GeoPoint(top.DataEndLat, curPoint.Longitude), new GeoPoint(bottom.DataStartLat, curPoint.Longitude));
curIndex++;
yield return(line);
}
}
}
private IEnumerable <GeoSegment> GetDEMWestEastLines(List <FileMetadata> segTiles, GeoPoint northernSegPoint, GeoPoint southernSegPoint, double registrationOffsetPx)
{
// Get the first north west tile and last south east tile.
// The lines are bounded by those tiles
foreach (var tilesByY in segTiles.GroupBy(t => t.DataStartLat).OrderByDescending(g => g.Key))
{
List <FileMetadata> WETilesOrdered = tilesByY.OrderBy(t => t.DataStartLon).ToList();
FileMetadata left = WETilesOrdered.First();
FileMetadata right = WETilesOrdered.Last();
GeoPoint curPoint = new GeoPoint(left.DataEndLat, left.DataStartLon);
// For cell registered datasets, DataStart is not matching the start data point. Start data point is at cell center (0.5 pixel off)
double endLat = left.FileFormat.Registration == DEMFileRegistrationMode.Cell
? left.DataEndLat + left.PixelScaleY / 2d
: left.DataEndLat;
// Y Index in tile coords
int curIndex = (int)Math.Floor((left.PhysicalEndLat - curPoint.Latitude) / left.PixelScaleY - -registrationOffsetPx);
while (IsPointInTile(left, curPoint))
{
if (curIndex >= left.Height)
{
break;
}
curPoint.Latitude = endLat + (left.pixelSizeY * curIndex);
if (curPoint.Latitude < southernSegPoint.Latitude)
{
break;
}
GeoSegment line = new GeoSegment(new GeoPoint(curPoint.Latitude, left.DataStartLon), new GeoPoint(curPoint.Latitude, right.DataEndLon));
curIndex++;
yield return(line);
}
}
}
public List <GeoPoint> GetLineGeometryElevation(IGeometry lineStringGeometry, DEMDataSet dataSet, InterpolationMode interpolationMode = InterpolationMode.Bilinear)
{
if (lineStringGeometry == null || lineStringGeometry.IsEmpty)
{
return(null);
}
if (lineStringGeometry.OgcGeometryType != OgcGeometryType.LineString)
{
throw new Exception("Geometry must be a linestring");
}
if (lineStringGeometry.SRID != 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);
var ptStart = lineStringGeometry.Coordinates[0];
var ptEnd = lineStringGeometry.Coordinates.Last();
GeoPoint start = new GeoPoint(ptStart.Y, ptStart.X);
GeoPoint end = new GeoPoint(ptEnd.Y, ptEnd.X);
double lengthMeters = start.DistanceTo(end);
int demResolution = dataSet.ResolutionMeters;
int totalCapacity = 2 * (int)(lengthMeters / demResolution);
double registrationOffset = dataSet.FileFormat.Registration == DEMFileRegistrationMode.Cell ? 0 : 0.5;
List <GeoPoint> geoPoints = new List <GeoPoint>(totalCapacity);
using (RasterFileDictionary adjacentRasters = new RasterFileDictionary())
{
bool isFirstSegment = true; // used to return first point only for first segments, for all other segments last point will be returned
foreach (GeoSegment segment in lineStringGeometry.Segments())
{
List <FileMetadata> segTiles = this.GetCoveringFiles(segment.GetBoundingBox(), dataSet, tiles);
// Find all intersection with segment and DEM grid
IEnumerable <GeoPoint> intersections = this.FindSegmentIntersections(segment.Start.Longitude
, segment.Start.Latitude
, segment.End.Longitude
, segment.End.Latitude
, segTiles
, isFirstSegment
, registrationOffset
, true);
// Get elevation for each point
intersections = this.GetElevationData(intersections, adjacentRasters, segTiles, interpolator);
// Add to output list
geoPoints.AddRange(intersections);
isFirstSegment = false;
}
//Debug.WriteLine(adjacentRasters.Count);
} // Ensures all rasters are properly closed
return(geoPoints);
}
public static IEnumerable <GeoPoint> CenterOnOrigin(this IEnumerable <GeoPoint> points, GeoPoint origin)
{
return(points.Translate(-origin.Longitude, -origin.Latitude, -origin.Elevation ?? 0));
}
public static IEnumerable <GeoPoint> Translate(this IEnumerable <GeoPoint> points, GeoPoint vector)
{
foreach (var pt in points)
{
var pout = pt.Clone();
pout.Latitude += vector.Latitude;
pout.Longitude += vector.Longitude;
pout.Elevation += vector.Elevation ?? 0;
yield return(pout);
}
}
/// <summary>
/// Return visibility report from first point to last point. We assume that all points are aligned.
/// WARNING: those calculations are not spherical (yet) and are not accurate for long distances.
/// <see cref="IntervisibilityMetrics"/>
/// </summary>
/// <param name="points">Input list of points, visibility is calculated for first and last points (ie: are they visible or is there a relief standing in between)</param>
/// <returns><see cref="IntervisibilityMetrics"/> object</returns>
internal static IntervisibilityMetrics ComputeVisibilityMetrics(IList <GeoPoint> points, bool visibilityCheck = true, double sourceVerticalOffset = 0d, double targetVerticalOffset = 0, double?noDataValue = null)
{
IntervisibilityMetrics metrics = new IntervisibilityMetrics();
if (points.Count == 0)
{
return(metrics);
}
GeoPoint A = points.First(), B = points.Last();
double hA = A.Elevation ?? 0d, hB = B.Elevation ?? 0d;
hA += sourceVerticalOffset;
hB += targetVerticalOffset;
double AB = A.DistanceTo(B);
visibilityCheck = visibilityCheck && (AB > double.Epsilon);
if (hA < hB)
{
MathHelper.Swap(ref A, ref B);
MathHelper.Swap(ref hA, ref hB);
}
double total = 0, minElevation = double.MaxValue, maxElevation = double.MinValue, totalClimb = 0, totalDescent = 0;
GeoPoint firstPoint = points[0];
firstPoint.DistanceFromOriginMeters = 0; // force at 0. If null, ignored in json responses
double lastElevation = firstPoint.Elevation ?? 0;
IntervisibilityObstacle obstacle = null;
double lastPeakElevation = 0;
int numNoDataPoints = 0;
for (int i = 1; i < points.Count; i++)
{
#region metrics
GeoPoint curPoint = points[i];
double v_dist = DistanceTo(curPoint, points[i - 1]);
total += v_dist;
curPoint.DistanceFromOriginMeters = total;
minElevation = Math.Min(minElevation, curPoint.Elevation ?? double.MaxValue);
maxElevation = Math.Max(maxElevation, curPoint.Elevation ?? double.MinValue);
numNoDataPoints += curPoint.Elevation == noDataValue ? 1 : 0;
double currentElevation = curPoint.Elevation ?? lastElevation;
double diff = currentElevation - lastElevation;
if (diff > 0)
{
totalClimb += diff;
}
else
{
totalDescent += diff;
}
#endregion
#region visibility checks
// Visibility check
// If obstacle hit, add it and
if (visibilityCheck)
{
double distToLowestPoint = curPoint.DistanceTo(B);
double visibilityElevationThreshold = (distToLowestPoint * (hA - hB)) / AB + hB;
if (currentElevation >= visibilityElevationThreshold)
{
if (obstacle == null)
{
obstacle = new IntervisibilityObstacle(curPoint, visibilityElevationThreshold);
lastPeakElevation = currentElevation;
obstacle.PeakPoint = curPoint;
}
else
{
// still inside obstacle, find peak
if (currentElevation > lastPeakElevation)
{
lastPeakElevation = currentElevation;
obstacle.PeakPoint = curPoint;
}
}
}
else
{
if (obstacle != null) // out of obstacle, register it
{
obstacle.ExitPoint = curPoint;
metrics.AddObstacle(obstacle);
obstacle = null;
}
}
}
if (i == points.Count - 1 && obstacle != null)
{
// Edge case: last point is exit point. We still have an active obstacle instance
// If obstacle entry is curPoint, this is the same point and this is not an obstacle
if (!obstacle.EntryPoint.Equals(curPoint))
{
obstacle.ExitPoint = curPoint;
metrics.AddObstacle(obstacle);
obstacle = null;
}
}
#endregion
lastElevation = currentElevation;
}
metrics.Climb = totalClimb;
metrics.Descent = totalDescent;
metrics.NumPoints = points.Count;
metrics.Distance = total;
metrics.MinElevation = minElevation;
metrics.MaxElevation = maxElevation;
metrics.HasVoids = numNoDataPoints > 0;
metrics.NumVoidPoints = numNoDataPoints;
return(metrics);
}
public static Vector3 AsVector3(this GeoPoint geoPoint)
{
return(new Vector3((float)geoPoint.Longitude, (float)geoPoint.Latitude, (float)(geoPoint.Elevation ?? 0D)));
}
public static Vector3 ToVector3GlTFSpace(this GeoPoint geoPoint)
{
return(ToGlTFSpace(new Vector3((float)geoPoint.Longitude, (float)geoPoint.Latitude, (float)(geoPoint.Elevation ?? 0D))));
}
public IntervisibilityObstacle(GeoPoint entryPoint, double visibilityElevationThreshold)
{
this.EntryPoint = entryPoint;
this.VisibilityElevationThreshold = visibilityElevationThreshold;
}
public static Vector3 ToVector3(this GeoPoint geoPoint)
{
return(new Vector3((float)geoPoint.Longitude, (float)geoPoint.Elevation, -(float)geoPoint.Latitude));
}
public GeoPoint GetPointElevation(GeoPoint location, DEMDataSet dataSet, InterpolationMode interpolationMode = InterpolationMode.Bilinear)
{
return(GetPointElevation(location.Latitude, location.Longitude, dataSet, interpolationMode));
}
public static BoundingBox AroundPoint(GeoPoint point, double size)
{
return(BoundingBox.AroundPoint(point.Latitude, point.Longitude, size));
}
public GeoSegment(GeoPoint start, GeoPoint end)
{
Start = start;
End = end;
}