/// <summary>
/// Returns the Cross Product of two vectors lhs and rhs
/// </summary>
/// <param name="lhs">Vector, the first input vector</param>
/// <param name="rhs">Vector, the second input vector</param>
/// <returns>A FloatVector3 containing the cross product of lhs and V</returns>
public static FloatVector3 operator ^(FloatVector3 lhs, FloatVector3 rhs)
{
FloatVector3 Result = new FloatVector3();
Result.X = (lhs.Y * rhs.Z - lhs.Z * rhs.Y);
Result.Y = (lhs.Z * rhs.X - lhs.X * rhs.Z);
Result.Z = (lhs.X * rhs.Y - lhs.Y * rhs.X);
return Result;
}
/// <summary>
/// Divides the components of vector lhs by the respective components
/// ov vector V and returns the resulting vector.
/// </summary>
/// <param name="lhs">FloatVector3 Dividend (Numbers to be divided)</param>
/// <param name="rhs">FloatVector3 Divisor (Numbers to divide by)</param>
/// <returns>A FloatVector3 quotient of lhs and V</returns>
/// <remarks>To prevent divide by 0, if a 0 is in V, it will return 0 in the result</remarks>
public static FloatVector3 operator /(FloatVector3 lhs, FloatVector3 rhs)
{
FloatVector3 result = new FloatVector3();
if (rhs.X > 0) result.X = lhs.X / rhs.X;
if (rhs.Y > 0) result.Y = lhs.Y / rhs.Y;
if (rhs.Z > 0) result.Z = lhs.Z / rhs.Z;
return result;
}
/// <summary>
/// Multiplies all the scalar members of the the two vectors
/// </summary>
/// <param name="lhs">Left hand side</param>
/// <param name="rhs">Right hand side</param>
/// <returns></returns>
public static float Dot(FloatVector3 lhs, FloatVector3 rhs)
{
return lhs.X * rhs.X + lhs.Y * rhs.Y + lhs.Z * rhs.Z;
}
/// <summary>
/// Multiplies the source vector by a scalar.
/// </summary>
/// <param name="source"></param>
/// <param name="scalar"></param>
/// <returns></returns>
public static FloatVector3 Multiply(FloatVector3 source, float scalar)
{
return new FloatVector3(source.X * scalar, source.Y * scalar, source.Z * scalar);
}
/// <summary>
/// Subtracts the specified value
/// </summary>
/// <param name="vector">A FloatVector3</param>
public void Subtract(FloatVector3 vector)
{
X -= vector.X;
Y -= vector.Y;
Z -= vector.Z;
}
/// <summary>
/// Returns the Cross Product of two vectors lhs and V
/// </summary>
/// <param name="lhs">Vector, the first input vector</param>
/// <param name="rhs">Vector, the second input vector</param>
/// <returns>A FloatVector3 containing the cross product of lhs and V</returns>
public static FloatVector3 CrossProduct(FloatVector3 lhs, FloatVector3 rhs)
{
FloatVector3 result = new FloatVector3();
result.X = (lhs.Y * rhs.Z - lhs.Z * rhs.Y);
result.Y = (lhs.Z * rhs.X - lhs.X * rhs.Z);
result.Z = (lhs.X * rhs.Y - lhs.Y * rhs.X);
return result;
}
/// <summary>
/// Subtracts all the scalar members of the the two vectors
/// </summary>
/// <param name="lhs">Left hand side</param>
/// <param name="rhs">Right hand side</param>
/// <returns></returns>
public static FloatVector3 Subtract(FloatVector3 lhs, FloatVector3 rhs)
{
return new FloatVector3(lhs.X - rhs.X, lhs.Y - rhs.Y, lhs.Z - rhs.Z);
}
/// <summary>
/// Adds the specified v
/// </summary>
/// <param name="vector">A FloatVector3 to add to this vector</param>
public void Add(FloatVector3 vector)
{
X += vector.X;
Y += vector.Y;
Z += vector.Z;
}
/// <summary>
/// Adds all the scalar members of the the two vectors
/// </summary>
/// <param name="lhs">Left hand side</param>
/// <param name="rhs">Right hand side</param>
/// <returns></returns>
public static FloatVector3 Add(FloatVector3 lhs, FloatVector3 rhs)
{
return new FloatVector3(lhs.X + rhs.X, lhs.Y + rhs.Y, lhs.Z + rhs.Z);
}
/// <summary>
/// Create Hillshade of values ranging from 0 to 1, or -1 for no-data regions.
/// This should be a little faster since we are accessing the Data field directly instead of working
/// through a value parameter.
/// </summary>
/// <param name="raster">The raster to create the hillshade from.</param>
/// <param name="shadedRelief">An implementation of IShadedRelief describing how the hillshade should be created.</param>
/// <param name="progressHandler">An implementation of IProgressHandler for progress messages</param>
public static float[][] CreateHillShade(this IRaster raster, IShadedRelief shadedRelief, IProgressHandler progressHandler)
{
int numCols = raster.NumColumns;
int numRows = raster.NumRows;
double noData = raster.NoDataValue;
float extrusion = shadedRelief.Extrusion;
float elevationFactor = shadedRelief.ElevationFactor;
float lightIntensity = shadedRelief.LightIntensity;
float ambientIntensity = shadedRelief.AmbientIntensity;
FloatVector3 lightDirection = shadedRelief.GetLightDirection();
float[] aff = new float[6]; // affine coefficients converted to float format
for (int i = 0; i < 6; i++)
{
aff[i] = Convert.ToSingle(raster.Bounds.AffineCoefficients[i]);
}
float[][] hillshade = new float[numRows][];
ProgressMeter pm = new ProgressMeter(progressHandler, MessageStrings.CreatingShadedRelief, numRows);
for (int row = 0; row < numRows; row++)
{
hillshade[row] = new float[numCols];
for (int col = 0; col < numCols; col++)
{
// 3D position vectors of three points to create a triangle.
FloatVector3 v1 = new FloatVector3(0f, 0f, 0f);
FloatVector3 v2 = new FloatVector3(0f, 0f, 0f);
FloatVector3 v3 = new FloatVector3(0f, 0f, 0f);
double val = raster.Value[row, col];
// Cannot compute polygon ... make the best guess
if (col >= numCols - 1 || row <= 0)
{
if (col >= numCols - 1 && row <= 0)
{
v1.Z = (float)val;
v2.Z = (float)val;
v3.Z = (float)val;
}
else if (col >= numCols - 1)
{
v1.Z = (float)raster.Value[row, col - 1]; // 3 - 2
v2.Z = (float)raster.Value[row - 1, col]; // | /
v3.Z = (float)raster.Value[row - 1, col - 1]; // 1 *
}
else if (row <= 0)
{
v1.Z = (float)raster.Value[row + 1, col]; // 3* 2
v2.Z = (float)raster.Value[row, col + 1]; // | /
v3.Z = (float)val; // 1
}
}
else
{
v1.Z = (float)val; // 3 - 2
v2.Z = (float)raster.Value[row - 1, col + 1]; // | /
v3.Z = (float)raster.Value[row - 1, col]; // 1*
}
// Test for no-data values and don't calculate hillshade in that case
if (v1.Z == noData || v2.Z == noData || v3.Z == noData)
{
hillshade[row][col] = -1; // should never be negative otherwise.
continue;
}
// Apply the Conversion Factor to put elevation into the same range as lat/lon
v1.Z = v1.Z * elevationFactor * extrusion;
v2.Z = v2.Z * elevationFactor * extrusion;
v3.Z = v3.Z * elevationFactor * extrusion;
// Complete the vectors using the latitude/longitude coordinates
v1.X = aff[0] + aff[1] * col + aff[2] * row;
v1.Y = aff[3] + aff[4] * col + aff[5] * row;
v2.X = aff[0] + aff[1] * (col + 1) + aff[2] * (row + 1);
v2.Y = aff[3] + aff[4] * (col + 1) + aff[5] * (row + 1);
v3.X = aff[0] + aff[1] * col + aff[2] * (row + 1);
v3.Y = aff[3] + aff[4] * col + aff[5] * (row + 1);
// We need two direction vectors in order to obtain a cross product
FloatVector3 dir2 = FloatVector3.Subtract(v2, v1); // points from 1 to 2
FloatVector3 dir3 = FloatVector3.Subtract(v3, v1); // points from 1 to 3
FloatVector3 cross = FloatVector3.CrossProduct(dir3, dir2); // right hand rule - cross direction should point into page... reflecting more if light direction is in the same direction
// Normalizing this vector ensures that this vector is a pure direction and won't affect the intensity
cross.Normalize();
// Hillshade now has an "intensity" modifier that should be applied to the R, G and B values of the color found at each pixel.
hillshade[row][col] = FloatVector3.Dot(cross, lightDirection) * lightIntensity + ambientIntensity;
}
pm.CurrentValue = row;
}
pm.Reset();
// Setting this indicates that a hillshade has been created more recently than characteristics have been changed.
shadedRelief.HasChanged = false;
return hillshade;
}
/// <summary>
/// Creates a CoordinateF by using the X, Y and Z terms of a FloatVector
/// </summary>
/// <param name="floatVector"></param>
public CoordinateF(FloatVector3 floatVector)
{
_x = floatVector.X;
_y = floatVector.Y;
_z = floatVector.Z;
_m = float.NaN;
}
