Using REST to perform server-side processing on image services is useful when creating web applications that offer image services that were processed with different methods, or when applications cannot perform the processing, for example:
- If the image service contains imagery, such as Landsat, a web application can be created to perform an NDVI using the red and near-infrared bands.
- If the image service is a DEM, a web application can be created to allow the user to view the image service as a hillshade, slope, or shaded relief image.
REST supports basic functions on image services, including aspect, color map, NDVI, slope, shaded relief, hillshade, statistics, and stretch. You can extend these capabilities by publishing an image service with an .rft.xml file where you can chain the raster functions together to create the processing result you need.
Applying raster function templates to an image service containing functions, such as stretch, is useful when the image services will be used in web applications. Web applications are often unable to enhance imagery, so they rely on server-side processing. In this situation, when you add a raster function template to the image service, you can choose to apply it by default.