生成3波段Raster图像代码 C#+Engine

昨天,一同事问我怎么用C#生成3波段Raster图像,这里把代码写出来.目前只能生成3个波段。当波段大于3时会出问题。不知道为什么，那位高手知道告诉俺一声。
public void CreateMultBandsRaster(string directoryName)//, string szFile, string szRasFormat /*= "IMAGINE Image"*/
        {
            Random random=new Random ();
  
            if (File.Exists("d:\vge.img"))
            {
                File.Delete("d:\vge.img");
            }
            IWorkspaceFactory m_WorkspaceFactory = new RasterWorkspaceFactoryClass();
            IRasterDataset m_RasterDataSet=null;
            IPoint originPoint = new PointClass();
            originPoint.PutCoords(0, 0);
            IRasterWorkspace2 m_RasterWorkspace2 = m_WorkspaceFactory.OpenFromFile("d:\", 0) as IRasterWorkspace2;

            IProjectedCoordinateSystem m_ProjectedCoordinateSystem;
            ISpatialReferenceFactory2 spatRefFact = new SpatialReferenceEnvironmentClass();
            m_ProjectedCoordinateSystem = spatRefFact.CreateProjectedCoordinateSystem((int)esriSRProjCSType.esriSRProjCS_WGS1984UTM_49N);

            m_RasterWorkspace2 = createRasterWorkspace(directoryName);
          
            m_RasterDataSet = m_RasterWorkspace2.CreateRasterDataset("vge.img", "IMAGINE Image", originPoint, 10,10, 1, 1, 6, rstPixelType.PT_UCHAR, m_ProjectedCoordinateSystem, true);
            
             IRaster m_Raster;
             RasterInfo rstInfo = new RasterInfo();
             rstInfo.lNumbands = 6;

             IRawPixels []m_RawPixels = new IRawPixels[rstInfo.lNumbands];
             m_Raster = m_RasterDataSet.CreateDefaultRaster();
             IRasterProps m_RasterProps = m_Raster as IRasterProps;
             // Get RasterBand from the raster
             IRasterBandCollection m_RasterBandCollection = m_Raster as IRasterBandCollection;
             IPixelBlock3[] m_PixelBlock = new IPixelBlock3[rstInfo.lNumbands];

             for (int i = 0; i < rstInfo.lNumbands; i++)
             {
                 m_RawPixels[i] = (IRawPixels)m_RasterBandCollection.Item(i);
             }
      /* */     
             //目前这个设置透明色值不管用，不知道正确的方法是怎么样
             /*if (bNoDataValue > 0 || bNoDataValue < 256) {
              VARIANT vVal;
              vVal.vt = VT_UI1;
              vVal.cVal = bNoDataValue;
             // ipRasProps->put_NoDataValue(vVal);
              ipRasProps->put_NoDataValue(CComVariant(bNoDataValue));
             }
             */// QI RawPixel interface
       
             m_RasterProps = m_Raster as IRasterProps;
             // Create a DblPnt to hold the PixelBlock size
             IPnt m_PixelBlockSize=new DblPntClass();            
             long lWidth, lHeight;
             lWidth=m_RasterProps.Width;
             lHeight = m_RasterProps.Height;
             m_PixelBlockSize.SetCoords(lWidth, lHeight);
             // Create PixelBlock with defined size
             IPnt pixelBlockOrigin = new DblPntClass();
             pixelBlockOrigin.SetCoords(0, 0);            
 
            System.Array[] pixelData = new System.Array[rstInfo.lNumbands];
            for (int i = 0; i < rstInfo.lNumbands; i++)
            {
                m_PixelBlock[i] =(IPixelBlock3)m_RawPixels[i].CreatePixelBlock(m_PixelBlockSize);//When There is more than 3 bands, error happens here.
                pixelData[i] = (System.Array)m_PixelBlock[i].get_PixelDataByRef(0);
               
                for (int ii = 0; ii < m_RasterProps.Width; ii++)
                    for (int jj = 0; jj < m_RasterProps.Height; jj++)
                    {
                        if (i == 0)
                            pixelData[i].SetValue(Convert.ToByte((ii*jj)%255), ii, jj);
                        else if (i == 1)
                        {
                            if((ii*jj)%255>130)
                                pixelData[i].SetValue(Convert.ToByte((ii * jj) % 255-130), ii, jj);//random.Next(100,110)
                            else
                                pixelData[i].SetValue(Convert.ToByte(130-(ii * jj) % 255), ii, jj);//random.Next(100,110)
                        }
                        else
                            pixelData[i].SetValue(Convert.ToByte(255 - (ii * jj) % 255), ii, jj);
                    }
                m_PixelBlock[i].set_PixelData(0, (System.Object)pixelData[i]);
               
                System.Object cachePointer;
                cachePointer = m_RawPixels[i].AcquireCache();
               m_RawPixels[i].Write(pixelBlockOrigin, (IPixelBlock)m_PixelBlock[i]);
               
                m_RawPixels[i].ReturnCache(cachePointer);
            }

            IRasterLayer pRasterLayer = new RasterLayerClass();
            pRasterLayer.CreateFromDataset(m_RasterDataSet);
            ILayer pLayer;
            pLayer = pRasterLayer;
            pLayer.Name = "New Raster";
            axMapControl1.Map.AddLayer(pLayer);
            axMapControl1.ActiveView.Refresh();
        }