NodataFilter

NodataFilter.cs

using System;
using ESRI.ArcGIS.DataSourcesRaster;
using ESRI.ArcGIS.Geodatabase;

namespace CustomNodataFilter
{
    //This sample shows the steps to create a customized pixelfilter
    //INodataFilter filters out a range of values in a raster to be nodata
    public interface INodataFilter : IPixelFilter
    {
        //IPixelFilter methods
        new void Filter(IPixelBlock pPixelBlock);
        new void GetCenterPosition(ref int x, ref int y);
        new void GetSize(ref int nCols, ref int nRows);

        //INodataFilter members
        int MinNodataValue { get; set;}
        int MaxNodataValue { get; set;}
    }

    public class NodataFilter : INodataFilter
    {
        public void Filter(IPixelBlock pPixelBlock)
        {
            try
            {
                IPixelBlock3 pPixelBlock3 = (IPixelBlock3)pPixelBlock;

                byte[] lookup = new byte[8] { 128, 64, 32, 16, 8, 4, 2, 1 };

                //get number of bands
                int plane = pPixelBlock.Planes;

                //loop through each band
                for (int i = 0; i < plane; i++)
                {
                    //get nodata mask array
                    byte[] outputArray = (byte[])pPixelBlock3.get_NoDataMaskByRef(i);

                    //loop through each pixel in the pixelblock and do calculation
                    for (int x = 0; x < pPixelBlock.Width; x++)
                    {
                        for (int y = 0; y < pPixelBlock.Height; y++)
                        {
                            //get index in the nodata mask byte array
                            int ind = x + y * (pPixelBlock.Width);

                            //get nodata mask byte 
                            byte nd = outputArray[ind / 8];

                            //get pixel value and check if it is nodata
                            object tempVal = pPixelBlock3.GetVal(i, x, y);

                            if (tempVal != null) //not nodata pixel
                            {
                                //convert pixel value to int and compare with nodata range

                                int curVal = Convert.ToInt32(tempVal);
                                if (curVal >= minNodataValue && curVal <= maxNodataValue)
                                {
                                    outputArray[ind / 8] = (byte)(nd & ~lookup[ind % 8]);
                                }
                            }
                        }
                    }
                    //set nodata mask array
                    pPixelBlock3.set_NoDataMask(i, outputArray);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
        }

        //implements IPixelFilter:GetCenterPosition
        public void GetCenterPosition(ref int x, ref int y)
        {
            x = 0;
            y = 0;
        }

        //implements IPixelFilter:GetSize
        public void GetSize(ref int nCols, ref int nRows)
        {
            nCols = 0;
            nRows = 0;
        }

        //get/set max range of nodata 
        public int MaxNodataValue
        {
            get
            {
                return maxNodataValue;
            }
            set
            {
                maxNodataValue = value;
            }
        }

        //get/set min range of nodata
        public int MinNodataValue
        {
            get
            {
                return minNodataValue;
            }
            set
            {
                minNodataValue = value;
            }
        }

        private int minNodataValue;
        private int maxNodataValue;

    }
}

NodataFilter.vb

Imports System
Imports ESRI.ArcGIS.DataSourcesRaster
Imports ESRI.ArcGIS.Geodatabase

'This sample shows the steps to create a customized pixelfilter
'INodataFilter filters out a range of values in a raster to be nodata
Public Interface INodataFilter
    Inherits IPixelFilter

    'INodataFilter members
    Property MinNodataValue() As Integer
    Property MaxNodataValue() As Integer

End Interface

Public Class NodataFilter
    Implements INodataFilter
    Sub Filter(ByVal pPixelBlock As IPixelBlock) Implements INodataFilter.Filter
        Dim x As Integer
        Dim y As Integer
        Try
            Dim pPixelBlock3 As IPixelBlock3 = CType(pPixelBlock, IPixelBlock3)

            Dim lookup() As Byte = New Byte(7) {128, 64, 32, 16, 8, 4, 2, 1}

            'get number of bands
            Dim plane As Integer = pPixelBlock.Planes

            'loop through each band
            Dim i As Integer
            For i = 0 To plane - 1
                'get nodata mask array
                Dim outputArray() As Byte = CType(pPixelBlock3.NoDataMask(i), Byte())

                'loop through each pixel in the pixelblock and do calculation

                For y = 0 To pPixelBlock.Height - 1
                    For x = 0 To pPixelBlock.Width - 1
                        'get index in the nodata mask byte array
                        Dim ind As Integer = x + y * (pPixelBlock.Width)

                        'get nodata mask byte 
                        Dim nd As Byte = outputArray(ind \ 8)

                        'get pixel value and check if it is nodata
                        Dim tempVal As Object = pPixelBlock3.GetVal(i, x, y)

                        If Not tempVal Is Nothing Then
                            'convert pixel value to int and compare with nodata range

                            Dim curVal As Integer = Convert.ToInt32(tempVal)
                            If curVal >= MinNodataValue And curVal <= MaxNodataValue Then
                                outputArray(ind \ 8) = CType((nd - lookup(ind Mod 8)), Byte)
                            End If
                        End If
                    Next
                Next
                'set nodata mask array
                pPixelBlock3.NoDataMask(i) = outputArray
            Next
        Catch e As Exception
            Console.WriteLine(e.Message)
        End Try
    End Sub

    'implements IPixelFilter:GetCenterPosition
    Public Sub GetCenterPosition(ByRef x As Integer, ByRef y As Integer) Implements INodataFilter.GetCenterPosition
        x = 0
        y = 0
    End Sub

    'implements IPixelFilter:GetSize
    Public Sub GetSize(ByRef nCols As Integer, ByRef nRows As Integer) Implements INodataFilter.GetSize
        nCols = 0
        nRows = 0
    End Sub

    'get/set max range of nodata 
    Public Property MaxNodataValue() As Integer Implements INodataFilter.MaxNodataValue
        Get
            Return maxNDValue
        End Get
        Set(ByVal Value As Integer)
            maxNDValue = Value
        End Set
    End Property

    'get/set min range of nodata
    Public Property MinNodataValue() As Integer Implements INodataFilter.MinNodataValue
        Get
            Return minNDValue
        End Get
        Set(ByVal Value As Integer)
            minNDValue = Value
        End Set
    End Property

    Private minNDValue As Integer
    Private maxNDValue As Integer

End Class