Defining and building service overviews

步骤：

1. Click the Image Service drop-down menu on the Image Service Definition Editor toolbar and click Advanced > Optimize > Service Overviews > Define.

   The Service Overview Parameters dialog box is displayed.

2. The following fields on the dialog box need to be filled in:

   Base Pixel Size	Base pixel size used to create service overviews. The generate service overview procedure creates images at pixel sizes corresponding to multiples of the overview factor and this value. The overview factor is set as part of the service defaults.
   Optimum Number of Rows	Optimum number of rows in the derived tile. The larger the value, the bigger the file and the more likely it will need to be regenerated if any lower image changes. More files are created if the value is small.
   Optimum Number of Cols	Optimum number of columns in the derived tile. The larger the value, the bigger the file and the more likely it will need to be regenerated if any lower image changes. More files are created if the value is small.
   Overview Factor	The factor to be used for the generation of overviews. The value can be 2, 3, 4, or 5. A factor of 2 results in an additional 33 percent imagery if service overviews are defined for rasters that have no internal overviews and the same compression is used. A factor of 3 results in an additional 13 percent.
   Derived Images Output Folder	Folder to which the derived tiles are output.
   Sampling Method	Sampling method to be used to create service overviews.
   Format	Format to be used to create external overviews. 警告: The JPEG 2000 format cannot be used to write files that are 32- or 64-bit.
   Compression Method	Method of compression to be used to create external overviews.
   Compression Quality	Compression quality to be used to create external overviews.
   Tile Size	Tile size that has to be used (for TIFF) to create external overviews.

3. Click OK.

   The Image Service Editor message box appears. It tells you that the service overviews have been generated and instructs you to build the image service definition, by checking the Generate derived images option, to generate the overview images.

4. Click OK.
5. Open the service table.

   You can see the newly added service overview added as a row in the table.

6. Click the Image Service drop-down menu on the Image Service Definition Editor toolbar and click Advanced > Build.
7. Check the Generate derived images option on the Build Options dialog box.
8. The Service Editor Report window displays a message when the build is completed.

   The service overview is added to the image service definition.

提示:

You can preview each service overview by browsing to the SO.Derived Images\SO folder (path specified in the Derived Images Output Folder text box) and opening each image.