如何从影像服务上按指定Polygon下载与其相交的Raster？

【解决办法】：
1，首先发布Image Service时有个Download功能处需要打钩，否则无法下载。 
2，imageServer3.Download(fidSet, clipGeometry, TIFF); 第二个参数处设置为ClipGeometry的话，在执行到url = imageServer3.GetFile(isDownloadResult);处会报错（错误为“The download file doesn''t exist.”），设置为null，则可以正常下载。因为之前做过空间查询了，已经将查询到的栅格ID存入IFIDSet中，所以只是想获取与ClipGeometry相交的影像可以将其设置为null。

IImageServer imageServer = null; 



//Set connection propertyset. sample URL: http://host:port/arcgis/services. 

IPropertySet propertySet = new PropertySetClass(); 

propertySet.SetProperty(url, https://zhuxinying.esrichina.c ... rvices); 



//Open an AGS connection. 

Type factoryType = Type.GetTypeFromProgID( 

esriGISClient.AGSServerConnectionFactory); 

IAGSServerConnectionFactory agsFactory = (IAGSServerConnectionFactory) 

Activator.CreateInstance(factoryType); 

IAGSServerConnection agsConnection = agsFactory.Open(propertySet, 0); 



//Get the image server. 

IAGSEnumServerObjectName agsServerObjectNames = agsConnection.ServerObjectNames; 

agsServerObjectNames.Reset(); 

IAGSServerObjectName agsServerObjectName = agsServerObjectNames.Next(); 

while (agsServerObjectName != null) 

{ 

if ((agsServerObjectName.Name.ToLower() == MosaicImageService.ToLower()) && 

(agsServerObjectName.Type == ImageServer)) 

{ 

IName pName = (IName)agsServerObjectName; 

IAGSServerObject agsServerObject = (IAGSServerObject)pName.Open(); 

imageServer = (IImageServer)agsServerObject; 

break; 

} 

agsServerObjectName = agsServerObjectNames.Next(); 

} 

IImageServer3 imageServer3 = (IImageServer3)imageServer; 



//Query the image service using the clip geometry. 

ISpatialFilter spatFilter = new ImageQueryFilterClass(); 

spatFilter.Geometry = clipGeometry; 

spatFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelEnvelopeIntersects; 

IFIDSet fidSet = imageServer3.GetCatalogItemIDs((IQueryFilter)spatFilter); 



//Define the Web client. 

System.Net.WebClient webClient = new System.Net.WebClient(); 



//Clip and download rasters to TIFF images. The format can be TIFF, NITF, or Imagine image file format. 

IImageServerDownloadResults isDownloadResults = imageServer3.Download(fidSet, 

null, TIFF); 

IImageServerDownloadResult isDownloadResult; 

string url, fileName; 

for (int i = 0; i < isDownloadResults.Count; i++) 

{ 

isDownloadResult = isDownloadResults.get_Element(i); 

url = imageServer3.GetFile(isDownloadResult); 

fileName = d:\\temp\\ + url.Substring(url.LastIndexOf(/) + 1); 

webClient.DownloadFile(url, fileName); 

}