Creating and editing process chains

Processes—such as Stretching to enhance an image, Stack Bands to combine multiple bands, and Colormap to render imagery using a color map—can be added as service processes that are applied to the raster data as it is being served. Sometimes the required processes are added to the service when the raster data is added to the image service definition, such as sharpening Landsat data or orthorectifying and pansharpening QuickBird data. However, there are many cases in which you need to define the processes. This is done using the Service Processes node on the Image Service Properties dialog box or the Raster Processes node on the Raster Properties dialog box.

You access the Service Processes node through the Image Service Properties dialog box to apply processes, such as NDVI or Pan-sharpen, to all the raster data in an image service definition. You access the Raster Processes node through the Raster Properties dialog box to apply processes to one or more rasters in the service, but not all. For example, if you have different types of raster data in an image service definition, such as a digital elevation model (DEM), scanned maps, and high-resolution imagery, you will likely apply different processes to each of these. You may want to use the Visualize Elevation process to apply a hillshade to the DEM, the Colormap process to properly render the scanned maps, and the Stretching process to enhance the imagery.

Learn more about the Image Server process chain

On the Raster Properties dialog box, there are two locations where you can apply processes; this is because the raster dataset can contain one or multiple rasters. When you click the Raster Processes node, you can add one or more processes that will be applied to all the rasters in a multiraster dataset. When you click the Rasters node, you can add one or more processes that will be applied to individual rasters within a multiraster dataset.

Sometimes you will notice processes that have been added by the system and their names are prefixed with Validator-. This means that this process was added during a validation operation performed on the image service definition where it looks to make sure the processed rasters match what is defined in the image service definition. For example, if you add a one-band raster dataset to a three-band image service definition, when you run Build with Compute Output Properties checked, a validation operation is run that checks for the mismatch and automatically adds an Extract Bands process along with the prefix. In this case, the Extract Bands process will convert the raster data from one band to three bands. The prefix is used so you know the process was added in this way.

Additionally, there is an alias parameter for each process. By default, a unique alias will be generated. You may edit the alias; however, it must be unique for each process within the process chain.

Etapes :

1. Click the Image Service Properties button on the Image Service Definition Editor toolbar or choose a single raster dataset and click the Raster Properties button .
2. On the Image Service Properties dialog box, click the Service Processes node on the left panel. On the Raster Properties dialog box, either click the Processes node on the left panel or click the Rasters node on the left panel and click the Processes tab.
3. Click the process name in the Processes Available list.
4. Optionally, click the Details button .

   This displays information about the process, such as the author, a description, and whether the radiometry or bits are changed by the process.

5. Click the Add Process button to add the process to the Processes Selected list.

   Each time the same process is added to the Processes Selected list, a number is appended to the alias—this number increases incrementally starting with 0 because the alias for each process in a process chain must be uniquely identified. This number will not be added if you have changed the alias of the process prior to adding the second same process. As you add processes to this list, you can reorder them using the Up button and Down button . When you have more than one in this list, you have a process chain. The top process in the list is applied first in the process chain.

6. Click the process in the Processes Selected list and click the Edit button to open the individual dialog box for each process, which allows you to edit the process settings.
   • Optionally, click a process in the Processes Selected list and click the Remove Process button to remove a process from the list.
   • Optionally, uncheck a process if you do not want to remove it from your chain but you do not want it to be applied.
7. Click OK.