Main Page: Basic concepts

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Map coverage Table Domain Representation Coordinate system Georeference
ILWIS Catalogs

There are several types of catalogs are defined in ILWIS namely: Master Catalog, System Catalog and Temporary Catalog. The Master Catalog in ILWIS can be viewed as a database that includes all the ILWIS objects on your system including directories and subdirectories tree. The Master Catalog can be filtered by various filters available from Data Managements Pane, Catalog filters, standard queries (see Figure 1). For example, selecting the Master Catalog Table from the list, displays all the available ILWIS tables in your system. The System Catalog includes IWIS system objects such as; Coordinate systems, datums, domains, ellipsoids, projections and representations. Temporary Catalog is, basically, used to keep temporary files generated via ILWIS operations.

ILWIS data objects and icons

There are several types of ILWIS objects: data objects, container objects, service objects, and special objects.
Data objects; are spatial data in form of vector and raster and tabular data. In new ILWIS, all types of vector maps (point, segment, polygon) are considered “Feature Coverage” and raster objects are referred to as “Raster Coverage”. Raster data include coverages derived from rasterizing vector maps, acquired from air/space-borne platforms, obtained as results of ILWIS operations. Tabular data are in form of table consisting of columns and records. Tabular data either linked to spatial coverages as an attribute table or as standalone table with no dependency. Data objects are visualized in a Catalog via icons such as:

ILWIS Container, Support and Operation objects and icons

Container objects; are collections of data objects:

Support objects; are used by data objects; they contain accessories that data objects need besides the data itself. Support objects can be selected to serve one or more data objects; they can be created, edited, etc. through the properties of an object. Examples of Support objects are:

Operation objects refer to all available operations in ILWIS. The operations can be viewed in the catalog when you select the default bookmark “Operations” in main window. The icons are used to display the operations are:

Operation objects.png