Fundamentals about building an image service definition

Legacy:

ArcGIS 10 is the last release of the stand-alone ArcGIS Image Server product. The image service definition (.ISDef) has been replaced by an improved geodatabase data model—the mosaic dataset—which can be published as an image service using the ArcGIS Server Image extension.

During the build stage, you are compiling or recompiling the information from the raster datasets to update the image service definition parameters, service table, and boundary that are part of the image service definition (.ISDef). The build process constructs and validates selected parts of the image service definition to derive parameters, including pixel size ranges, metadata fields, image service boundary, and images, used for optimization. You need to build the image service definition to preview, optimize, or compile the service.

When should you build an image service definition?

Typically, you will build the image service definition after you have added raster data to an image service. You will also build the image service definition after you have created (defined) derived tiles, service overviews, and derived rasters to generate the corresponding raster datasets. You might need to build the image service definition if you add processes that will affect the parameters, such as adding the Grayscale process, which would change the output from RGB to grayscale.

After you build the image service definition the first time, the Boundary layer will be added to the image service definition group layer in the ArcMap table of contents. You can also display the Preview layer within the group layer.

Understanding the options on the Build Options dialog box

• Compute pixel size ranges—When checked, this option computes the minimum and maximum pixel size ranges assigned to each raster dataset. The pixel size ranges are used to determine which rasters need to be processed to create an image for the client. The ranges have to be calculated when an image service definition is first built. The pixel size ranges are derived from the high and low pixel sizes for each raster dataset in the service table. You can manually edit the pixel size ranges for each raster dataset in the service table. You can uncheck the Compute pixel size ranges option for any subsequent builds; however, if you have added new raster data to the image service definition, keep this option checked unless you intend to edit them manually. To learn more about these ranges, see Pixel size ranges used.
• Create service boundary—When checked, this generates a boundary shapefile containing all the raster datasets in the image service definition. This should be checked the first time you build an image service definition. You can uncheck this option for any subsequent builds; however, if you have added new raster data to the image service definition that would change the boundary, you need to keep this option checked. To learn more about the image service definition boundary, see Working with the Boundary layer.
• Compute output pixel properties—When checked, this calculates the output pixel properties calculated in one of two ways: if there are no processes defined for an image service definition, the output pixel properties are calculated based on the image service definition properties; otherwise, if a process or process chain is defined, one of the raster datasets will pass through the service process or chain and the output properties will be calculated accordingly. Therefore, you need to ensure that the process is valid even when the raster is disabled in a particular raster dataset. Having invalid processes in the raster dataset may result in the build operation failing while computing the output pixel properties. This must be checked the first time you build an image service definition. You can uncheck this option for any subsequent builds; however, if you made any changes to the service processes, you need to keep this option checked.

  Histograms are now generated when the Compute output pixel properties option is checked while building an image service definition. Histogram statistics are extracted based on the image size. After you generate the histogram, you should compile the service and publish it to view the statistics of the image service on the Source and Symbology tabs of the Layer Properties dialog box in ArcMap.

  Note:

  For some services (primarily the ones that do not contain overviews), generation of histograms may fail. In such cases, you can see a warning message in the Reporter window stating that the histogram generation has failed. This failure does not affect the image service, and you can continue to use the service. However, you will not be able to view the histogram and the statistics in the Layer Properties when the service is published. By default, image service definitions created using New Image Service Wizard will not contain histogram statistics. Check the Compute output properties option and the Compile option, on the Build dialog box, to generate the histogram statistics.

• Extract metadata fields—When checked, this extracts and saves any additional metadata provided with the raster data in the image service definition in the service table. This metadata might comprise cloud cover values, dates, azimuth values, and so on. Check this only when you want to obtain this metadata as you first build the image service definition or if you have added any additional raster data to the image service definition.
• Generate derived images—When checked, this generates any optimization images that have been defined. Check this only when you need to generate or regenerate these images—either when they are created or if you have made any changes to them or added raster datasets that will change the appearance of the imagery served by the image service definition.

  Changing image service processes does not require the regeneration of a service overview, since image service processes are applied to all the raster datasets including the service overviews. However, if you change the processes applied on individual raster datasets, they will have to be regenerated.

• Validate raster sources—When checked, this option verifies that raster sources are valid raster datasets. Check this only when you are not sure about the source of your rasters; it may contain errors, which can be detected during validation.
• Validate raster process defn. files—When checked, the process verifies that valid processes are defined in the raster process definition (.RPDef) files. To learn more about .RPDef files, see About the raster process definition.
• Compile service—When checked, this option compiles the image service definition to create the .ISCDef file used to publish the image service.
• Load preview—When checked, this option loads the preview after building the image service definition.

During the build process, a Service Editor-Building window appears displaying the progress and status of the build process along with any warnings and errors encountered. Warnings and errors are also appended to the service table in the StatusID and StatusMSG fields.