/// <summary>
/// Clips a raster with a polygon feature
/// </summary>
/// <param name="polygon">The clipping polygon feature</param>
/// <param name="input">The input raster object</param>
/// <param name="outputFileName">the output raster file name</param>
/// <param name="cancelProgressHandler">Progress handler for reporting progress status and cancelling the operation</param>
/// <remarks>We assume there is only one part in the polygon.
/// Traverses the raster with a vertical scan line from left to right, bottom to top</remarks>
/// <returns></returns>
public static IRaster ClipRasterWithPolygon(IFeature polygon, IRaster input, string outputFileName,
ICancelProgressHandler cancelProgressHandler = null)
{
//if the polygon is completely outside the raster
if (!input.ContainsFeature(polygon))
return input;
if (cancelProgressHandler != null)
cancelProgressHandler.Progress(null, 16, "Retrieving the borders.");
List<Border> borders = GetBorders(polygon);
if (cancelProgressHandler != null)
cancelProgressHandler.Progress(null, 33, "Copying raster.");
//create output raster
IRaster output = Raster.CreateRaster(outputFileName, input.DriverCode, input.NumColumns, input.NumRows, 1,
input.DataType, new[] { string.Empty });
output.Bounds = input.Bounds.Copy();
output.NoDataValue = input.NoDataValue;
if (input.CanReproject)
{
output.Projection = input.Projection;
}
// set all initial values of Output to NoData
for (int i = 0; i < output.NumRows; i++)
{
for (int j = 0; j < output.NumColumns; j++)
{
output.Value[i, j] = output.NoDataValue;
}
}
double xStart = GetXStart(polygon, output);
int columnStart = GetStartColumn(polygon, output); //get the index of first column
double xCurrent = xStart;
ProgressMeter pm = new ProgressMeter(cancelProgressHandler, "Clipping Raster", output.NumColumns);
pm.StepPercent = 5;
pm.StartValue = 33;
int col = 0;
for (int columnCurrent = columnStart; columnCurrent < output.NumColumns; columnCurrent++)
{
xCurrent = xStart + col * output.CellWidth;
var intersections = GetYIntersections(borders, xCurrent);
intersections.Sort();
ParseIntersections(intersections, xCurrent, columnCurrent, output, input);
// update progess meter
pm.CurrentValue = xCurrent;
//update counter
col++;
// cancel if requested
if (cancelProgressHandler != null && cancelProgressHandler.Cancel)
return null;
}
output.Save();
return output;
}
/// <summary>
/// Clips a raster with a polygon feature.
/// </summary>
/// <param name="polygon">The clipping polygon feature.</param>
/// <param name="input">The input raster object.</param>
/// <param name="outputFileName">the output raster file name.</param>
/// <param name="cancelProgressHandler">Progress handler for reporting progress status and cancelling the operation.</param>
/// <remarks>We assume there is only one part in the polygon.
/// Traverses the raster with a vertical scan line from left to right, bottom to top.</remarks>
/// <returns>The raster resulting from the clip operation.</returns>
public static IRaster ClipRasterWithPolygon(IFeature polygon, IRaster input, string outputFileName, ICancelProgressHandler cancelProgressHandler = null)
{
// if the polygon is completely outside the raster
if (!input.ContainsFeature(polygon))
{
return(input);
}
cancelProgressHandler?.Progress(16, "Retrieving the borders.");
List <Border> borders = GetBorders(polygon);
cancelProgressHandler?.Progress(33, "Copying raster.");
// create output raster
IRaster output = Raster.CreateRaster(outputFileName, input.DriverCode, input.NumColumns, input.NumRows, 1, input.DataType, new[] { string.Empty });
output.Bounds = input.Bounds.Copy();
output.NoDataValue = input.NoDataValue;
if (input.CanReproject)
{
output.Projection = input.Projection;
}
// set all initial values of Output to NoData
for (int i = 0; i < output.NumRows; i++)
{
for (int j = 0; j < output.NumColumns; j++)
{
output.Value[i, j] = output.NoDataValue;
}
}
double xStart = GetXStart(polygon, output);
int columnStart = GetStartColumn(polygon, output); // get the index of first column
ProgressMeter pm = new ProgressMeter(cancelProgressHandler, "Clipping Raster", output.NumColumns)
{
StepPercent = 5, StartValue = 33
};
int col = 0;
for (int columnCurrent = columnStart; columnCurrent < output.NumColumns; columnCurrent++)
{
var xCurrent = xStart + (col * output.CellWidth);
var intersections = GetYIntersections(borders, xCurrent);
intersections.Sort();
ParseIntersections(intersections, xCurrent, columnCurrent, output, input);
// update progess meter
pm.CurrentValue = xCurrent;
// update counter
col++;
// cancel if requested
if (cancelProgressHandler != null && cancelProgressHandler.Cancel)
{
return(null);
}
}
output.Save();
return(output);
}
