///<summary>
      ///空值处理 Author：AllenRobin http://gisrsman.cnblogs.com
      ///</summary>
      private static void Null2Number(IGeoDataset pRaster, string outPath,double number)
        {
            //检查出为空的位置（null区位1，非null区为0）
            string isNullPath = System.IO.Path.Combine(Application.StartupPath, "isnull.tif");
            Geoprocessor gp = new Geoprocessor();    //初始化Geoprocessor
            gp.OverwriteOutput = true;                     //允许运算结果覆盖现有文件
            ESRI.ArcGIS.SpatialAnalystTools.IsNull isnullgp = new ESRI.ArcGIS.SpatialAnalystTools.IsNull();
            isnullgp.in_raster = pRaster;
            isnullgp.out_raster = isNullPath;
            gp.Execute(isnullgp, null);

            //将空（即是1）的设为0，其余设为原始值
            Geoprocessor gp1 = new Geoprocessor();          
            gp1.OverwriteOutput = true;                   
            ESRI.ArcGIS.SpatialAnalystTools.Con congp = new ESRI.ArcGIS.SpatialAnalystTools.Con();
            congp.in_conditional_raster = isNullPath;
            congp.out_raster = outPath;
            congp.where_clause = "Value = 1";//value=1的地方即是查询出来的Null的地方
            congp.in_false_raster_or_constant = pRaster;
            congp.in_true_raster_or_constant =number;//将null改为0或其他值  
            gp1.Execute(congp, null); 
         }