Creating a Thematic Map |
|
|
The procedure for creating thematic cartograms is designed to generate graphical images that visually illustrate the relationship between values of a selected characteristic for individual objects on an electronic map.
This procedure processes objects that have been previously selected on the source electronic map (for example, using search and selection tools). The information according to which the selected map objects will be colored can be contained in the semantics of the objects themselves, in a user database table of .dbf type, or in .txt text files. Both tables previously linked to the map and those without map connections can be used to create thematic maps. Linked tables are characterized by the presence of LINKSHEET and LINKOBJECT fields in their structure, containing references to specific objects on a specific map. The LINKSHEET field stores the nomenclature (conventional name) of the sheet where the corresponding object is located, while the LINKOBJECT field contains its unique number. However, if you are using a table without direct links to map objects, you should ensure the possibility of establishing such a connection. This means that the semantics of selected objects must contain values (linking semantics) that can be uniquely matched with values in the corresponding field of a specific record in the processed table (linking field). For example, you have a map of the administrative division of the Russian Federation, where regions are represented as polygons with a code (number) of the corresponding region in their semantics, and a table containing information about regions, one of whose fields is the region code. The connection can be established using both numerical and string values (for example, Region Name), with the only restriction being that the linking semantics and linking field must be of the same type (both numerical or both string).
Note: This mode does not work with point objects!
The procedure's dialog window contains Data, View, and Legend.
The sequence of tabs corresponds to the recommended sequence of actions when creating a thematic cartogram, meaning that for successful procedure execution, you need to sequentially access all tabs and make the appropriate settings.
|
