ILWIS objects |
Object collections |
An object collection is a set of ILWIS objects. An object collection only stores the names and locations of the maps, tables, etc. that are included in the object collection but not the data itself. References to the names and locations of the data files on disk are in the object definition files of the maps and tables etc. themselves.
Object collections:
A database collection is a special form of an object collection. While an object collection may contain all kinds of ILWIS objects (maps, tables, layouts, etc.), a database collection may only contain tables. The tables of a database collection are in Use As mode u.
A database collection is the result of:
You are not allowed to add any tables to a database collection, and you cannot delete any tables from a database collection. To obtain a database collection and some general information on database collections, refer to ILWIS objects : tables - databases.
Except for the technical information, in which both object collections and database collections are treated, the remainder of this topic deals with object collections.
Names of object collections:
In ILWIS 3, object names comply with Windows long file names. Also Universal Naming Convention (UNC) paths are supported. For more information, see How to use long object names.
To create an object collection:
Open the File menu in the Main window and select the Create Object Collection command, or double-click the New Object Collection item in the Operation-list. In the appearing Create Object Collection dialog box, you can enter a name and description for the object collection. The object collection will be directly opened.
Note:
An object collection is automatically created when importing ASTER level 1A or level 1B images through ILWIS Map Import.
To add objects to an object collection:
To add objects to an object collection:
This is the same as using Copy and Paste. For more information, see How to copy objects.
You can add objects from various directories to an object collection.
Tip:
You can choose whether a Catalog should show:
The setting can be specified on the Customize Catalog, Object Selection page.
Note:
Imported objects will be automatically added to the created object collection when importing ASTER level 1A or level 1B images through ILWIS Map Import.
To open an object collection and to open the objects it contains:
To open an object collection, you can double-click it in a Catalog.
In turn, to open objects that are part of an object collection: double-click them in the opened object collection.
Operations on (objects in) object collections:
As object collections may contain any kind of objects (map lists, maps, domains, georeferences, etc.), no operations can be performed on object collections as a whole. Object collections are only used to store the location on disk of the objects they contain.
On maps and tables IN an object collection, you can perform the same operations as usual. When the data object(s) on which an operation is performed are in the same object collection, the output of the operation will also be stored in the object collection.
Technical information:
An object collection only consists of an ASCII object definition file (.IOC). The object definition file contains further references to the objects that are included in the object collection.
Similarly, a database collection uses the same type an ASCII object definition file as an object collection (.IOC). The object definition file of a database collection contains further references to the tables that are included in the database collection. The object definition files of the tables (.TBT) that are part of a database collection, are only created when a (Use As) table of a database collection is opened.
If you like, you can save a Use As table to a normal ILWIS table by using Save Copy As from the File menu of a table window which displays a Use As table. You will then obtain an object definition file for the table (.TBT) and a data file for the table (.TB#).
By viewing the properties of an object collection, you can see on the Contains tab, the names of the objects that are included in the object collection. When the object collection is a database collection, the Contains tab lists the names of the tables that are included in the database collection. For more information, see the Object Collection Properties sheet.
See also: