/// <summary>
/// 2．水流方向计算
/// 水流方向计算就可以使用上一步所生成的DEM为源数据了
///（如果使用未经洼地填平处理的数据，可能会造成精度下降）
/// 算法说明：计算某个单元格附近八个（不足的不考虑）的最小高程（最大高程差）
/// 结果说明：若有一个最小的，流向指向最小的；若有多个最小的继续分别计算几个最小值附近的最小值
/// 水流方向计算之后返回的是1-128表示流向的值
///一直递归找到最小值的那一项 </summary>
/// <param name="src"></param>
/// <returns></returns>
public static double[,] FlowDirection(this double[,] src)
{
int rowCount = src.GetLength(0);
int colCount = src.GetLength(1);
double[,] result = new double[rowCount, colCount];
for (int row = 0; row < rowCount; row++)
{
for (int col = 0; col < colCount; col++)
{
result[row, col] = CalFlowDirection(rowCount, colCount, row, col, src);
FormCalView.SetColor(row, col, (int)result[row, col]);
}
}
return(result);
}
/// <summary>
/// 3．水流积聚计算
/// 可以看到，生成的水流积聚栅格已经可以看到所产生的河网了。
/// 现在所需要做的就是把这些河网栅格提取出来。可以把产生的河网的支流的象素值作为阀值来提取河网栅格。
/// </summary>
/// <param name="src"></param>
/// <returns></returns>
public static double[,] Accumulation(this double[,] src)
{
int rowCount = src.GetLength(0);
int colCount = src.GetLength(1);
double[,] result = new double[rowCount, colCount]; //定义结果
Dictionary <Grid, List <Grid> > dicCaledAll = new Dictionary <Grid, List <Grid> >();
Queue <Grid> queueGrid = new Queue <Grid>();
Dictionary <Grid, int> unFindOutGrid = new Dictionary <Grid, int>();
for (int row = 0; row < rowCount; row++)
{
for (int col = 0; col < colCount; col++)
{
//将数据添加到方程组中
Grid tempGrid = new Grid(row, col);
queueGrid.Enqueue(tempGrid);
unFindOutGrid.Add(tempGrid, 0); //添加默认为零
dicCaledAll.Add(tempGrid, GetFlowAround(src, tempGrid));
}
}
Dictionary <Grid, int> findOutGrid = new Dictionary <Grid, int>();
FormCalView.SetAllSize(rowCount, colCount);
FormOutput.AppendProress(true);
//开始解方程
while (queueGrid.Count > 0)
{
FormOutput.AppendProress(findOutGrid.Count * 100 / dicCaledAll.Count);
Grid tGrid = queueGrid.Dequeue();
List <Grid> lstGrid = dicCaledAll[tGrid];
//找到数据
if (lstGrid.Count == 0)
{
result[tGrid.i, tGrid.j] = unFindOutGrid[tGrid];
findOutGrid.Add(tGrid, unFindOutGrid[tGrid]);
dicCaledAll.Remove(tGrid);
//unFindOutGrid.Remove(tGrid);
FormCalView.SetColor(tGrid.i, tGrid.j, unFindOutGrid[tGrid]);
}
else
{
List <Grid> lstTemp = new List <Grid>();
lstTemp.AddRange(dicCaledAll[tGrid]);
//循环寻找当前找出的Grid
for (int i = 0; i < lstGrid.Count; i++)
{
Grid temp = lstGrid[i];
if (ContainsGrid(findOutGrid, temp))
{
Grid temp1 = FindGrid(unFindOutGrid, temp);
Grid temp2 = FindGrid(findOutGrid, temp);
unFindOutGrid[temp1] = unFindOutGrid[temp1] + findOutGrid[temp2] + 1;
lstTemp.Remove(temp);
}
}
if (lstTemp.Count == 0)
{
result[tGrid.i, tGrid.j] = unFindOutGrid[tGrid];
findOutGrid.Add(tGrid, unFindOutGrid[tGrid]);
dicCaledAll.Remove(tGrid);
// unFindOutGrid.Remove(tGrid);
FormCalView.SetColor(tGrid.i, tGrid.j, unFindOutGrid[tGrid]);
}
else
{
dicCaledAll[tGrid] = lstTemp;
queueGrid.Enqueue(tGrid);
}
}
}
return(result);
}