static public Image GenerateShadedReliefImage(
IRasterDigitalElevationModel dem,
IShadingMethod shadingMethod,
ShadingParameters shadingParameters)
{
Bitmap bitmap = new Bitmap(dem.LonLength, dem.LatLength);
double[][] window = new double[3][] { new double[3], new double[3], new double[3] };
double earthRadius = 6360000;
double earthCircumference = earthRadius * 2 * Math.PI;
double latSpacing = earthCircumference / (360 * dem.LatResolution);
shadingMethod.Initialize(shadingParameters);
for (int y = 1; y < dem.LatLength - 1; y++)
{
GeoPosition geoPos = dem.GetGeoPosition(0, y);
double lonSpacing = earthCircumference / (360 * dem.LonResolution) * Math.Cos(geoPos.Latitude * Math.PI / 180.0);
for (int x = 1; x < dem.LonLength - 1; x++)
{
GetMovingWindow(dem, window, x, y);
double dzdx = ((window[0][0] + 2 * window[0][1] + window[0][2])
- (window[2][0] + 2 * window[2][1] + window[2][2]))
/ (8 * lonSpacing);
if (double.IsNaN(dzdx))
{
continue;
}
double dzdy = ((window[0][0] + 2 * window[1][0] + window[2][0])
- (window[0][2] + 2 * window[1][2] + window[2][2]))
/ (8 * latSpacing);
if (double.IsNaN(dzdy))
{
continue;
}
double riseRun = Math.Sqrt(dzdx * dzdx + dzdy * dzdy);
double slope = Math.PI / 2 - Math.Atan(riseRun);
double aspect = Math.Atan2(dzdy, dzdx);
//double aspect = Math.Atan2 (window[1][0] - window[1][2],
// window[0][1] - window[2][1]);
if (dzdx != 0 || dzdy != 0)
{
if (aspect == 0)
{
aspect = Math.PI * 2;
}
}
else
{
aspect = 0;
}
Color color = shadingMethod.CalculateColor(aspect, slope);
bitmap.SetPixel(x, bitmap.Height - y, color);
}
}
return(bitmap);
}
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);
}
static public IList <PointOfInterest> FindPeaks(IRasterDigitalElevationModel dem, int howMany)
{
IList <PointOfInterest> peaks = new List <PointOfInterest> ();
Point2 <int>[] neighbourPoints = { new Point2 <int> (-1, 0), new Point2 <int> (1, 0), new Point2 <int> (0, -1),
new Point2 <int> (0, 1) };
for (int x = 1; x < dem.LonLength - 1; x++)
{
for (int y = 1; y < dem.LatLength - 1; y++)
{
double elevation = dem.GetElevationForDataPoint(x, y);
// first check if it is a peak
bool isPeak = true;
for (int i = 0; i < neighbourPoints.Length; i++)
{
if (elevation <= dem.GetElevationForDataPoint((int)(x + neighbourPoints[i].X), (int)(y + neighbourPoints[i].Y)))
{
isPeak = false;
break;
}
}
if (isPeak)
{
for (int i = 0; i < peaks.Count + 1; i++)
{
bool addPeak = false;
if (i == peaks.Count)
{
addPeak = true;
}
else
{
PointOfInterest peak = peaks[i] as PointOfInterest;
if (elevation > peak.Position.Elevation)
{
addPeak = true;
}
}
if (addPeak)
{
PointOfInterest newPeak = new PointOfInterest(dem.GetGeoPosition(x, y),
String.Format(System.Globalization.CultureInfo.InvariantCulture, "Peak {0}", elevation));
peaks.Insert(i, newPeak);
if (peaks.Count > howMany)
{
peaks.RemoveAt(peaks.Count - 1);
}
break;
}
}
}
}
}
return(peaks);
}
