Setting a Catalog's Basic Properties

After you have added a catalog you may specify properties that govern how that catalog will be available for viewing. The basic properties of a catalog are:

• name
• catalog folder (this is a noneditable field)
• enable status (whether or not the catalog should be available through Express Server)
• index status (whether or not the catalog should be spatially indexed)
• overview status (whether or not an overview should be created for the catalog)
• EPSG code (the catalog's coordinate reference system)
• band mapping

Restrictions on Catalog Names

Commas and spaces are not allowed as catalog names. You may use numbers and letters, dashes and underscores.

Enabling a Catalog

Only enabled catalogs are available for delivery by Express Server. Both single catalogs and catalog groups can be enabled or disabled. You might disable a catalog if for any reason you do not want it to be accessible.

To enable a catalog:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs or Catalog Groups on the top navigation bar, then select a catalog or a catalog group in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Select the Enabled checkbox and click Save.
5. If you have no further settings to edit, click Publish.

To disable a catalog (make it unavailable), clear the Enabled checkbox.

You may enable or disable catalog groups as well as individual catalogs.By default all newly created catalogs and catalog groups are enabled.

Remember that clicking Save in the workspace only temporarily saves your changes until you click Publish or Discard. Clicking Publish sends all edits on all the configuration pages to the live Express Server. Clicking Discard overwrites all pages of the workspace with the current live configuration.

Indexing a Catalog

In order for a catalog to be available as a WMS layer it must be spatially indexed. The spatial index tells Express Server everything it needs to know to assemble the images in a catalog into a georeferenced mosaic that can be requested as a WMS layer.

Express Server indexes each catalog automatically when it is added, except when:

• a catalog contains one or more images with no georeferencing.
• a catalog contains images in more than one coordinate reference system
• a catalog contains one or more images whose well-known-text string (WKT) has an EPSG code that does not match its explicit parameters

Express Server examines the first three in a catalog and if they share a single EPSG code, then that is the code that is used for the index. If Express Server cannot automatically index a catalog and you wish that catalog to be spatially indexed, manually create an index for the catalog.

To create an index for a catalog:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs on the top navigation bar, then select a catalog in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Select the Index checkbox. Specify the EPSG code (see Specifying an EPSG Codeand Finding the EPSG Code for an Image).
5. Click Save.
6. If you have no further settings to edit, click Publish.

If you want the images in a catalog to remain individually georeferenced, you may specify that the catalog should not be indexed.

To specify that a catalog should not be indexed:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs on the top navigation bar, then select a catalog in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Clear the Index checkbox and click Save.
5. If you have no further settings to edit, click Publish.

If changes are made to an indexed catalog outside the Express Server Configuration page, such as the addition of images to that folder, you must update the spatial index (see Updating a Spatial Index).

Generating an Overview

An overview image is a single MrSID image encoded from low-resolution scenes of all the component images. Adding an overview image to a catalog will significantly improve performance for low-resolution requests. For example, without an overview image, a catalog that contains 4000 images will have to have pixels from each of those images decoded to produce a 640x480 scene of the entire dataset. This may require several minutes. When an overview image is added, however, the same request will access only one image, returning a result in a few seconds or less.

To generate an overview:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs on the top navigation bar, then select a catalog in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Select the Index checkbox if it is not already selected. The Overview checkbox becomes available.
5. Select the Overview checkbox and click Save.
6. If you have no further settings to edit, click Publish.

Specifying an EPSG Code

All the images in a catalog must be in the same coordinate reference system in order for them to be used as a spatially indexed catalog. Without a spatial index a catalog cannot be used as a WMS layer.

Express Server automatically detects the EPSG code for the first three images of a catalog, and if they are the same, assigns that EPSG code to spatial index for that catalog. If one or more of those initial images does not have one, no EPSG code is assigned to the catalog, but you may enter one manually. If, in attempting to create a spatial index, Express Server detects that the EPSG code listed in a well-known-text string (WKT) does not match its explicit parameters, you will be prompted to supply a valid EPSG code (for more information, see Finding the EPSG Code for an Image).

To specify an EPSG code:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs on the top navigation bar, then select a catalog in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Select the Index checkbox if it is not already selected. The "EPSG code" field becomes available.
5. Enter a valid code in the EPSG code field, then click Save.
6. If you have no further settings to edit, click Publish.

Mapping Bands

For images that have more than one band, you can select the bands that you want Express Server to deliver and the order of the bands. This process is called band mapping. You can map bands for MG4 images, NITF images, and JPEG 2000 images. Band mapping will be ignored for source images of any other type.

For RGB output you can choose any three bands in any order. For grayscale output you can choose any single band. If you select "Default", Express Server delivers the first band of an image for grayscale and the first three bands in their original order for RGB output.

To map bands in a catalog:

1. Open the Express Server Manager (see Accessing the Express Server Manager).
2. Click Catalogs on the top navigation bar, then select a catalog in the list.
3. Select Basic on the left-hand navigation, then click Edit.
4. Select a radio button. If you selected Grayscale, enter the desired band number. If you selected RGB, enter the desired band numbers in the desired order.
5. Click Save.
6. If you have no further settings to edit, click Publish.

NOTE: A catalog group cannot be band-mapped. Individual catalogs comprising a catalog group must be band-mapped separately.