Arcgis Engine 自定义栅格分类渲染(排除不想要的值)

      在做栅格分类渲染的时候，大家有可能想排除一些不想要的值，如背景值或异常值，在ArcMap中对应的功能就是Exclusion，如下图。

      那么，二次开发的时候怎么写呢？，其实，只要利用IRasterDataExclusion这个接口就可以实现，根据官方开发文档查了下分级的类RasterClassifyColorRampRendererClass所对应的接口就一目了然了。

      实现代码如下：

if (pLayer != null && pLayer is IRasterLayer)
            {
                IRasterLayer pRasterLayer = pLayer as IRasterLayer; 
                IRasterBandCollection bands = null;
                bands = (pRasterLayer.Raster as IRaster2).RasterDataset as IRasterBandCollection;
                
                IRasterBand pRasterBand = bands.Item(0);
                //如果没有统计数据，则计算
                if (pRasterBand.Histogram == null)
                {
                    pRasterBand.ComputeStatsAndHist();
                }

                IRasterClassifyColorRampRenderer ClassifyColor = new RasterClassifyColorRampRendererClass();
                IRasterRenderer pRasterRenderer = ClassifyColor as IRasterRenderer;
                pRasterRenderer.Raster = pRasterLayer.Raster;
                
                //设置分级 （我这里set_break的index从1开始）
                ClassifyColor.ClassCount = 3;
                ClassifyColor.set_Break(1, 0.27099);
                ClassifyColor.set_Break(2, 1.77287);
                ClassifyColor.set_Break(3, 2.77287);

                //排除数值（大家可以根据需要自行设置，我这张图-999是背景值）
                double[] ignoredValue = new double[1] { -999 };
                IRasterDataExclusion pRasterDataExclusion = ClassifyColor as IRasterDataExclusion;
                pRasterDataExclusion.ExcludeValues = ignoredValue;

                //颜色设置  
                IFillSymbol Symbol = new SimpleFillSymbolClass() as IFillSymbol;
                Symbol.Color = SetRGB(0, 255, 102);
                ClassifyColor.set_Symbol(0, Symbol as ISymbol);
                Symbol.Color = SetRGB(255, 255, 100);
                ClassifyColor.set_Symbol(1, Symbol as ISymbol);
                Symbol.Color = SetRGB(255, 153, 0);
                ClassifyColor.set_Symbol(2, Symbol as ISymbol);

                pRasterLayer.Renderer = pRasterRenderer;

                //设置标签(必须在设置分级之后才能设置标签)
                ClassifyColor.set_Label(0, "低聚区");
                ClassifyColor.set_Label(1, "中聚区");
                ClassifyColor.set_Label(2, "高聚区");

                pRasterRenderer.Update();

                m_mapControl.ActiveView.Refresh();
                m_TOCControl.Update();
            }

        private IColor SetRGB(int R,int G,int B)
        {
            IRgbColor pRgbColor=new RgbColorClass();
            pRgbColor.Red = R;
            pRgbColor.Green = G;
            pRgbColor.Blue = B;
            return (IColor)pRgbColor;
        }