/// <summary>
/// Example of how to get from a geographical coordinate to an (j,k) index
/// in the 2D grid. It also shows how to get the closest cell value and how
/// to perform bilinear interpolation.
/// <para>
/// The method assumes that the OresundHD.dfs2 test file is the input file.
/// </para>
/// </summary>
/// <param name="filename">Path and name of OresundHD.dfs2 test file</param>
public static void GetjkIndexForGeoCoordinate(string filename)
{
Dfs2File file = DfsFileFactory.Dfs2FileOpen(filename);
// The spatial axis is a EqD2 axis
IDfsAxisEqD2 axis = (IDfsAxisEqD2)file.SpatialAxis;
// Data for first time step
IDfsItemData2D <float> data = (IDfsItemData2D <float>)file.ReadItemTimeStep(1, 0);
// Get the projection and create a cartography object
IDfsProjection projection = file.FileInfo.Projection;
DHI.Projections.Cartography cart = new DHI.Projections.Cartography(projection.WKTString, projection.Longitude, projection.Latitude, projection.Orientation);
// Coordinates just south of Amager
double lon = 12.59;
double lat = 55.54;
// Get the (x,y) grid coordinates
double x;
double y;
cart.Geo2Xy(lon, lat, out x, out y);
Console.Out.WriteLine("Grid coordinates (x,y) = ({0:0.000},{1:0.000})", x, y);
Console.Out.WriteLine("Relative grid coordinates (x,y) = ({0:0.000},{1:0.000})", x / axis.Dx, y / axis.Dy);
// Calculate the cell indices of the lon-lat coordinate.
// The cell extents from its center and +/- 1/2 dx and dy
// in each direction
int j = (int)(x / axis.Dx + 0.5); // 30
int k = (int)(y / axis.Dy + 0.5); // 27
Console.Out.WriteLine("Value in cell ({0},{1}) = {2}", j, k, data[j, k]);
// If you want to interpolate between the values, calculate
// the (j,k) indices of lower left corner and do bilinear interpolation.
// This procedure does not take delete values into account!!!
j = (int)(x / axis.Dx); // 30
k = (int)(y / axis.Dy); // 26
double xFrac = (x % axis.Dx) / axis.Dx; // fraction of j+1 value
double yFrac = (y % axis.Dy) / axis.Dy; // fraction of k+1 value
double vk = (1 - xFrac) * data[j, k] + xFrac * data[j + 1, k];
double vkp1 = (1 - xFrac) * data[j, k + 1] + xFrac * data[j + 1, k + 1];
double v = (1 - yFrac) * vk + yFrac * vkp1;
Console.Out.WriteLine("Interpolated value = {0}", v);
file.Close();
}
/// <summary>
/// Create dfsu and mesh file from dfs2 file.
/// <para>
/// Note 1: Boundary code is set to land value at
/// all boundaries of mesh and dfsu file.
/// These must be updated to something "better"
/// if to use as input in another simulation.
/// </para>
/// <para>
/// Note 2: P and Q values are not rotated with the
/// grid, but should be so, if used in the
/// projected coordinate system. It must take
/// the 327 degrees rotation into account.
/// </para>
/// </summary>
/// <param name="dfs2Filename">Name of input dfs2 file, e.g. the OresundHD.dfs2</param>
/// <param name="meshFilename">Name of output mesh file</param>
/// <param name="dfsuFilename">Name of output dfsu file</param>
public static void CreateDfsuFromDfs2(string dfs2Filename, string meshFilename, string dfsuFilename)
{
// Open file
Dfs2File dfs2 = DfsFileFactory.Dfs2FileOpen(dfs2Filename);
// Read bathymetry from first static item
IDfsStaticItem bathymetryItem = dfs2.ReadStaticItemNext();
float[] bathymetry = (float[])bathymetryItem.Data;
// Extract spatial axis
IDfsAxisEqD2 spatialAxis = (IDfsAxisEqD2)dfs2.SpatialAxis;
// Some convenience variables
double dx = spatialAxis.Dx;
double dy = spatialAxis.Dy;
double x0 = spatialAxis.X0;
double y0 = spatialAxis.Y0;
int xCount = spatialAxis.XCount;
int yCount = spatialAxis.YCount;
// First custom block (index 0) contains the M21_MISC values,
// where the 4th (index 3) is the land value
float landValue = (float)dfs2.FileInfo.CustomBlocks[0][3];
//-----------------------------------------
// Find out which elements in the dfs2 grid that is not a land value
// and include all those elements and their surrounding nodes in mesh
// Arrays indicating if element and node in grid is used or not in mesh
bool[,] elmts = new bool[xCount, yCount];
int[,] nodes = new int[xCount + 1, yCount + 1];
// Loop over all elements in 2D grid
for (int l = 0; l < yCount; l++)
{
for (int k = 0; k < xCount; k++)
{
// If bathymetry is not land value, use element.
if (bathymetry[k + l * xCount] != landValue)
{
// element [l,k] is used, and also the 4 nodes around it
elmts[k, l] = true;
nodes[k, l] = 1;
nodes[k + 1, l] = 1;
nodes[k, l + 1] = 1;
nodes[k + 1, l + 1] = 1;
}
}
}
//-----------------------------------------
// Create new mest nodes
// Cartography object can convert grid (x,y) to projection (east,north)
IDfsProjection proj = dfs2.FileInfo.Projection;
DHI.Projections.Cartography cart = new DHI.Projections.Cartography(proj.WKTString, proj.Longitude, proj.Latitude, proj.Orientation);
// New mesh nodes
List <double> X = new List <double>();
List <double> Y = new List <double>();
List <float> Zf = new List <float>(); // float values for dfsu file
List <double> Zd = new List <double>(); // double values for mesh file
List <int> Code = new List <int>();
// Loop over all nodes
int nodesCount = 0;
for (int l = 0; l < yCount + 1; l++)
{
for (int k = 0; k < xCount + 1; k++)
{
// Check if node is included in mesh
if (nodes[k, l] > 0)
{
// Convert from mesh (x,y) to projection (east,north)
double east, north;
cart.Xy2Proj((k - 0.5) * dx + x0, (l - 0.5) * dy + y0, out east, out north);
// Average Z on node from neighbouring grid cell values, cell value is used
// unless they are outside grid or has land values
double z = 0;
int zCount = 0;
if (k > 0 && l > 0 && bathymetry[k - 1 + (l - 1) * xCount] != landValue)
{
zCount++; z += bathymetry[k - 1 + (l - 1) * xCount];
}
if (k < xCount && l > 0 && bathymetry[k + (l - 1) * xCount] != landValue)
{
zCount++; z += bathymetry[k + (l - 1) * xCount];
}
if (k > 0 && l < yCount && bathymetry[k - 1 + (l) * xCount] != landValue)
{
zCount++; z += bathymetry[k - 1 + (l) * xCount];
}
if (k < xCount && l < yCount && bathymetry[k + (l) * xCount] != landValue)
{
zCount++; z += bathymetry[k + (l) * xCount];
}
if (zCount > 0)
{
z /= zCount;
}
else
{
z = landValue;
}
// Store new node number and add node
nodesCount++;
nodes[k, l] = nodesCount; // this is the node number to use in the element table
X.Add(east);
Y.Add(north);
Zf.Add((float)z);
Zd.Add(z);
Code.Add(zCount == 4 ? 0 : 1); // Land boundary if zCount < 4
}
}
}
// New mesh elements
List <int[]> elmttable2 = new List <int[]>();
for (int l = 0; l < yCount; l++)
{
for (int k = 0; k < xCount; k++)
{
// Check if element is included in mesh
if (elmts[k, l])
{
// For this element, add the four surrounding nodes,
// counter-clockwise order
int[] newNodes = new int[4];
newNodes[0] = nodes[k, l];
newNodes[1] = nodes[k + 1, l];
newNodes[2] = nodes[k + 1, l + 1];
newNodes[3] = nodes[k, l + 1];
elmttable2.Add(newNodes);
}
}
}
//-----------------------------------------
// Create mesh
{
// Create 2D dfsu file
MeshBuilder builder = new MeshBuilder();
// Setup header and geometry
builder.SetNodes(X.ToArray(), Y.ToArray(), Zd.ToArray(), Code.ToArray());
builder.SetElements(elmttable2.ToArray());
builder.SetProjection(dfs2.FileInfo.Projection);
// Create new file
MeshFile mesh = builder.CreateMesh();
mesh.Write(meshFilename);
}
//-----------------------------------------
// Create dfsu file
{
// dfs2 time axis
IDfsEqCalendarAxis timeAxis = (IDfsEqCalendarAxis)dfs2.FileInfo.TimeAxis;
// Create 2D dfsu file
DfsuBuilder builder = DfsuBuilder.Create(DfsuFileType.Dfsu2D);
// Setup header and geometry
builder.SetNodes(X.ToArray(), Y.ToArray(), Zf.ToArray(), Code.ToArray());
builder.SetElements(elmttable2.ToArray());
builder.SetProjection(dfs2.FileInfo.Projection);
builder.SetTimeInfo(timeAxis.StartDateTime, timeAxis.TimeStepInSeconds());
builder.SetZUnit(eumUnit.eumUmeter);
// Add dynamic items, copying from dfs2 file
for (int i = 0; i < dfs2.ItemInfo.Count; i++)
{
IDfsSimpleDynamicItemInfo itemInfo = dfs2.ItemInfo[i];
builder.AddDynamicItem(itemInfo.Name, itemInfo.Quantity);
}
// Create new file
DfsuFile dfsu = builder.CreateFile(dfsuFilename);
// Add dfs2 data to dfsu file
float[] dfsuData = new float[dfsu.NumberOfElements];
for (int i = 0; i < dfs2.FileInfo.TimeAxis.NumberOfTimeSteps; i++)
{
for (int j = 0; j < dfs2.ItemInfo.Count; j++)
{
// Read dfs2 grid data
IDfsItemData2D <float> itemData = (IDfsItemData2D <float>)dfs2.ReadItemTimeStep(j + 1, i);
// Extract 2D grid data to dfsu data array
int lk = 0;
for (int l = 0; l < yCount; l++)
{
for (int k = 0; k < xCount; k++)
{
if (elmts[k, l])
{
dfsuData[lk++] = itemData[k, l];
}
}
}
// write data
dfsu.WriteItemTimeStepNext(itemData.Time, dfsuData);
}
}
dfsu.Close();
}
dfs2.Close();
}
