public void Isoplete(IRasterDigitalElevationModel dem, double elevationStep, NewIsohypseCallback callback)
{
DigitalElevationModelStatistics statistics = dem.CalculateStatistics();
double minElevation = Math.Floor(statistics.MinElevation / elevationStep) * elevationStep;
double maxElevation = Math.Floor(statistics.MaxElevation / elevationStep) * elevationStep;
//if (visualizer != null)
//{
// GeoPosition geoPosMin = dem.GetGeoPosition (0, 0, false);
// GeoPosition geoPosMax = dem.GetGeoPosition (dem.LonLength, dem.LatLength, false);
// visualizer.Initialize (geoPosMin.Longitude, geoPosMin.Latitude,
// geoPosMax.Longitude, geoPosMax.Latitude);
//}
Array2 <byte> flags = new Array2 <byte> (dem.LonLength - 1, dem.LatLength - 1);
Array2 <IsohypseMovement> movements = new Array2 <IsohypseMovement> (dem.LonLength - 1, dem.LatLength - 1);
int[,] adjacentCells = new int[, ] {
{ 0, 0 }, { 1, 0 }, { 1, 1 }, { 0, 1 }
};
// foreach elevation step
for (double isoElev = minElevation; isoElev <= maxElevation; isoElev += elevationStep)
{
activityLogger.Log(ActivityLogLevel.Normal, String.Format(System.Globalization.CultureInfo.InvariantCulture,
"Analyzing elevation {0}", isoElev));
//if (visualizer != null)
//{
// GeoPosition geoPosMin = dem.GetGeoPosition (0, 0, false);
// GeoPosition geoPosMax = dem.GetGeoPosition (dem.LongLength, dem.LatLength, false);
// visualizer.Initialize (geoPosMin.Longitude, geoPosMin.Latitude,
// geoPosMax.Longitude, geoPosMax.Latitude);
// for (int x = 0; x < dem.LongLength; x++)
// {
// for (int y = 0; y < dem.LatLength; y++)
// {
// int elevation = dem.GetElevation (x, y);
// GeoPosition geoPos = dem.GetGeoPosition (x, y);
// string color = elevation >= isoElev ? "orange" : "yellow";
// visualizer.DrawPoint (color, geoPos.Longitude, geoPos.Latitude);
// visualizer.DrawText ("pink", geoPos.Longitude, geoPos.Latitude, elevation.ToString ());
// }
// }
//}
Isohypse isohypse = new Isohypse(isoElev);
flags.Initialize(0);
movements.Initialize(0);
for (int x = 0; x < dem.LonLength - 1; x++)
{
for (int y = 0; y < dem.LatLength - 1; y++)
{
byte cellCharacteristic = 0;
for (int i = 0; i < adjacentCells.GetLength(0); i++)
{
double adjacentCellElev = dem.GetElevationForDataPoint(x + adjacentCells[i, 0], y + adjacentCells[i, 1]);
if (adjacentCellElev >= isoElev)
{
cellCharacteristic++;
flags.SetValue((byte)(flags.GetValue(x, y) | (byte)(1 << i)), x, y);
}
}
// skip cells which are definitively not along the isohypse
if (cellCharacteristic == 0 || cellCharacteristic == 4)
{
continue;
}
if (cellCharacteristic == 2)
{
int maskedFlags = flags.GetValue(x, y) & 0x9;
if (maskedFlags == 0 || maskedFlags == 0x9)
{
movements.SetValue(IsohypseMovement.North | IsohypseMovement.South, x, y);
}
else
{
maskedFlags = flags.GetValue(x, y) & 0x3;
if (maskedFlags == 0 || maskedFlags == 0x3)
{
movements.SetValue(IsohypseMovement.West | IsohypseMovement.East, x, y);
}
else
{
movements.SetValue(
IsohypseMovement.West | IsohypseMovement.East | IsohypseMovement.North | IsohypseMovement.South,
x, y);
}
}
}
else
{
int maskedFlags = flags.GetValue(x, y) & 0x3;
if (maskedFlags != 0 && maskedFlags != 0x3)
{
movements.SetValue(movements.GetValue(x, y) | IsohypseMovement.North, x, y);
}
maskedFlags = flags.GetValue(x, y) & 0x6;
if (maskedFlags != 0 && maskedFlags != 0x6)
{
movements.SetValue(movements.GetValue(x, y) | IsohypseMovement.East, x, y);
}
maskedFlags = flags.GetValue(x, y) & 0xc;
if (maskedFlags != 0 && maskedFlags != 0xc)
{
movements.SetValue(movements.GetValue(x, y) | IsohypseMovement.South, x, y);
}
maskedFlags = flags.GetValue(x, y) & 0x9;
if (maskedFlags != 0 && maskedFlags != 0x9)
{
movements.SetValue(movements.GetValue(x, y) | IsohypseMovement.West, x, y);
}
}
//if (visualizer != null)
//{
// if (cellCharacteristic > 0 && cellCharacteristic < 4)
// {
// GeoPosition geoPos = dem.GetGeoPosition (x + 0.5, y + 0.5);
// if (movements.GetValue (x, y)
// == (IsohypseMovement.West | IsohypseMovement.East | IsohypseMovement.North | IsohypseMovement.South))
// visualizer.DrawText ("blue", geoPos.Longitude, geoPos.Latitude,
// "X");
// //visualizer.DrawText ("blue", geoPos.Longitude, geoPos.Latitude,
// // cellCharacteristic == 2 ? "K" : "T");
// //List<Point2> points = new List<Point2> ();
// //if ((movements[x, y] & IsohypseMovement.North) != 0)
// // points.Add (new Point2 (0.5, 0));
// //if ((movements[x, y] & IsohypseMovement.East) != 0)
// // points.Add (new Point2 (1, 0.5));
// //if ((movements[x, y] & IsohypseMovement.South) != 0)
// // points.Add (new Point2 (0.5, 1));
// //if ((movements[x, y] & IsohypseMovement.West) != 0)
// // points.Add (new Point2 (0, 0.5));
// //List<GeoPosition> geoPoints = new List<GeoPosition> ();
// //foreach (Point2 point in points)
// // geoPoints.Add (dem.GetGeoPosition (x + point.X, y + point.Y));
// //visualizer.DrawLine ("black", geoPoints[0].Longitude, geoPoints[0].Latitude,
// // geoPoints[1].Longitude, geoPoints[1].Latitude);
// //if (geoPoints.Count > 2)
// // visualizer.DrawLine ("black", geoPoints[2].Longitude, geoPoints[2].Latitude,
// // geoPoints[3].Longitude, geoPoints[3].Latitude);
// }
//}
}
}
for (int x = 0; x < dem.LonLength - 1; x++)
{
for (int y = 0; y < dem.LatLength - 1; y++)
{
if (movements.GetValue(x, y) != IsohypseMovement.None)
{
IsohypseMovements isohypseMovements = ExtractIsohypseMovements(dem, isoElev, movements, flags, x, y);
Polyline isohypseSegment = ConstructIsohypseSegment(dem, isohypseMovements);
isohypseSegment.RemoveDuplicateVertices();
isohypse.AddSegment(isohypseSegment);
activityLogger.Log(ActivityLogLevel.Verbose, String.Format(System.Globalization.CultureInfo.InvariantCulture,
"Found segment with {0} vertices", isohypseSegment.VerticesCount));
}
}
}
if (isohypse.Segments.Count > 0)
{
callback(isohypse);
}
//isoColl.AddIsohypse (isohypse);
}
}
private Polyline ConstructIsohypseSegment(IRasterDigitalElevationModel dem, IsohypseMovements isohypseMovements)
{
Polyline polyline = new Polyline();
polyline.IsClosed = isohypseMovements.IsClosed;
int x = isohypseMovements.StartingX;
int y = isohypseMovements.StartingY;
bool checkedOrientation = false;
bool shouldBeReversed = false;
foreach (IsohypseMovement movement in isohypseMovements.Movements)
{
int dx1 = 0, dx2 = 0, dy1 = 0, dy2 = 0;
switch (movement)
{
case IsohypseMovement.East:
x++;
dx1 = dx2 = x;
dy1 = y;
dy2 = y + 1;
break;
case IsohypseMovement.North:
dx1 = x;
dx2 = x + 1;
dy1 = dy2 = y;
y--;
break;
case IsohypseMovement.South:
y++;
dx1 = x + 1;
dx2 = x;
dy1 = dy2 = y;
break;
case IsohypseMovement.West:
dx1 = dx2 = x;
dy1 = y + 1;
dy2 = y;
x--;
break;
}
double elevation1 = dem.GetElevationForDataPoint(dx1, dy1);
double elevation2 = dem.GetElevationForDataPoint(dx2, dy2);
// check the orientation of the isohypse
if (false == checkedOrientation)
{
// the right-side elevation should be higher
if (elevation2 < elevation1)
{
shouldBeReversed = true;
}
}
double factor = (isohypseMovements.IsohypseElevation - elevation1) / (elevation2 - elevation1);
double ix, iy;
ix = (factor * (dx2 - dx1) + dx1);
iy = (factor * (dy2 - dy1) + dy1);
GeoPosition geoPos = dem.GetGeoPosition(ix, iy);
Point3 <double> isohypseVertex = new Point3 <double> (geoPos.Longitude, geoPos.Latitude, isohypseMovements.IsohypseElevation);
polyline.AddVertex(isohypseVertex);
}
// now reverse the polyline if needed
if (shouldBeReversed)
{
polyline.Reverse();
}
return(polyline);
}
private IsohypseMovements ExtractIsohypseMovements(
IRasterDigitalElevationModel dem,
double isohypseElevation,
Array2 <IsohypseMovement> movements,
Array2 <byte> flags,
int startingX,
int startingY)
{
IsohypseMovements isohypseMovements = new IsohypseMovements(isohypseElevation);
isohypseMovements.StartingX = startingX;
isohypseMovements.StartingY = startingY;
int x = isohypseMovements.StartingX;
int y = isohypseMovements.StartingY;
int lastX = 0, lastY = 0;
IsohypseMovement lastMovement = IsohypseMovement.None;
bool foundOneEnd = false;
while (true)
{
// if we reached the end of the grid
if (x < 0 || y < 0 || x >= dem.LonLength - 1 || y >= dem.LatLength - 1)
{
// have we already found one end of the segment?
if (false == foundOneEnd)
{
// we haven't...
foundOneEnd = true;
// ... so reverse the segment and start moving from the other end
int oldStartingX = isohypseMovements.StartingX;
int oldStartingY = isohypseMovements.StartingY;
isohypseMovements.ReverseIsohypseMovements(x, y);
x = oldStartingX;
y = oldStartingY;
}
else
{
// we have, so we can exit
break;
}
}
if (x == isohypseMovements.StartingX &&
y == isohypseMovements.StartingY &&
isohypseMovements.Movements.Count > 0)
{
// we found the starting point, this is a closed polygon
isohypseMovements.IsClosed = true;
break;
}
IsohypseMovement currentCellMovement = movements.GetValue(x, y);
bool movementFound = false;
for (int i = 0; i < 4; i++)
{
IsohypseMovement movementConsidered = (IsohypseMovement)(1 << i);
if (0 != (currentCellMovement & movementConsidered))
{
int nextX = x, nextY = y;
switch (movementConsidered)
{
case IsohypseMovement.East:
nextX++;
break;
case IsohypseMovement.North:
nextY--;
break;
case IsohypseMovement.South:
nextY++;
break;
case IsohypseMovement.West:
nextX--;
break;
default:
throw new NotImplementedException();
}
// find the opposite movement of the last movement
IsohypseMovement oppositeMovement = IsohypseMovements.GetOppositeMovement(lastMovement);
if (lastMovement != IsohypseMovement.None)
{
// check that we haven't moved back
if (nextX == lastX && nextY == lastY)
{
continue;
}
// special case when all movements are possible
if ((((int)currentCellMovement) & 0xf) == 0xf)
{
IsohypseMovement movementCombination = movementConsidered | oppositeMovement;
// check that we haven't moved in such a way as to make the polygon cross itself
if ((movementCombination & (IsohypseMovement.North | IsohypseMovement.South))
== (IsohypseMovement.North | IsohypseMovement.South))
{
continue;
}
// check that we haven't moved in such a way as to make the polygon cross itself
if ((movementCombination & (IsohypseMovement.West | IsohypseMovement.East))
== (IsohypseMovement.West | IsohypseMovement.East))
{
continue;
}
// check that the movement is the right one in regards to cells elevations
if (flags.GetValue(x, y) == 5)
{
if (movementCombination == (IsohypseMovement.South | IsohypseMovement.East) ||
movementCombination == (IsohypseMovement.North | IsohypseMovement.West))
{
continue;
}
}
else if (flags.GetValue(x, y) == 10)
{
if (movementCombination == (IsohypseMovement.South | IsohypseMovement.West) ||
movementCombination == (IsohypseMovement.North | IsohypseMovement.East))
{
continue;
}
}
else
{
throw new NotImplementedException();
}
}
}
isohypseMovements.Movements.Add(movementConsidered);
// remove the used movement from the array
movements.SetValue(movements.GetValue(x, y) & ~movementConsidered, x, y);
// remove this opposite movement from the array
movements.SetValue(movements.GetValue(x, y) & ~oppositeMovement, x, y);
lastX = x;
lastY = y;
lastMovement = movementConsidered;
x = nextX;
y = nextY;
movementFound = true;
break;
}
}
if (movementFound == false)
{
throw new NotImplementedException();
}
}
return(isohypseMovements);
}