栅格重分类方法
栅格重分类方法很多，在AE中有多种方式可以实现，使用地图代数（在RasterModel中实现），或者IReclassOp，或者Geoprocessor的方式都可以，甚至可以遍历栅格来实现，这是最原始的方式，不过也可能是最实用的。
这里使用的是最原始的遍历栅格的方式。
Public Function reclass(ByVal pRaster As IRaster, ByVal extent As ArrayList, ByVal value As ArrayList, ByVal NoData As Single) As IRaster
'得倒栅格的IRasterProps和IRawPixels
Dim pRasterBands As IRasterBandCollection
pRasterBands = pRaster
Dim pRasterBand As IRasterBand
pRasterBand = pRasterBands.Item(0)
Dim pRawRixels As IRawPixels
pRawRixels = pRasterBands.Item(0)
Dim pRasterPro As IRasterProps
pRasterPro = pRasterBand
'设置栅格数据起始点
Dim pBlockSize As IPnt
pBlockSize = New Pnt()
pBlockSize.SetCoords(pRasterPro.Width, pRasterPro.Height)
'在栅格上创建pPixBlock，用来存放栅格数据
Dim pPixelBlock As IPixelBlock
pPixelBlock = pRaster.CreatePixelBlock(pBlockSize)
'左上点坐标
Dim tlp As IPnt = New Pnt()
tlp.SetCoords(0, 0)
'读入栅格
pRawRixels.Read(tlp, pPixelBlock)
'将PixBlock的值组成数组
Dim pSafeArray As System.Array
pSafeArray = pPixelBlock.SafeArray(0)
'遍历每一个栅格，进行分类设置
For y As Long = 0 To pRasterPro.Height - 1
For x As Long = 0 To pRasterPro.Width - 1
'判断每个栅格的所属类，确定其属于哪一类，然后进行赋值，即重分类
For i As Integer = 0 To extent.Count - 1
'如果值< 0，说明该处为空值（Nodata），赋给这个栅格相应的值
If CType(pSafeArray.GetValue(x, y), Single) < 0 Then
pSafeArray.SetValue(NoData, x, y)
Exit For
End If
'判断栅格属于哪一类，进行赋值
If CType(pSafeArray.GetValue(x, y), Single) <= CType(extent(i), Single) Then
pSafeArray.SetValue(value(i), x, y)
Exit For
End If
Next
Next
Next
'将数组赋给PixBlock
pPixelBlock.SafeArray(0) = CType(pSafeArray, System.Array)
'编辑raster，将更新的值写入raster中
Dim rasterEdit As IRasterEdit
rasterEdit = pRaster
rasterEdit.Write(tlp, pPixelBlock)
rasterEdit.Refresh()
Return pRaster
End Function