Topic Map Overview

A Topic map is a type of map that uses various graphic styles (such as color or fill mode) to graphically display basic map information. Topic map is a powerful way to analyze and present data. By graphical data, the data image is displayed on the topic map, we can clearly see the patterns and trends that are almost impossible to find in the data list, and make the map content topical and usage specialized.

Normally, GIS products can output two different maps, common maps and special maps. The difference between the two maps is that common maps emphasize geographical locations and Their Relationships. These maps have multiple geographical features, and the symbols in the maps have the same importance; A Topic map emphasizes the representation of specific elements or concepts.

Compared with a general map, a special map has the following features:

① A Topic map consists of the topic content and geographical map. The geographical basemap is based on a general map and re-compiled according to the needs of the topic content. The topic content cannot be isolated and must be attached to a certain geographical basis. The two are at different levels. A geographical map is an integral part of a thematic map.

② A Topic Map displays only one or more topic-related elements in detail, while other elements are outlined or not displayed.

③ The content of the topic map is more extensive and diverse. In addition to the natural or cultural phenomena that can be intuitively seen or measured, there are also natural or humanistic phenomena that are often invisible or cannot be directly measured. For example, climate, ocean stream, and ethnic composition.

④ It not only represents the current situation and distribution of the elements to be described, but also represents its dynamic changes and development patterns.

Categories of thematic maps can be classified by thematic content into natural maps (atmospheric phenomena, geology, terrain, hydrology, etc), Social and Economic Map (population, economy, social undertakings, administrative divisions, history, etc.), environmental map (environmental background conditions, environmental pollution status quo, environmental prediction, natural disasters, etc) and other thematic maps (maps other than the above types ). Categories are shown in the form of topic maps, it can be divided into a range of thematic maps, a level symbol Thematic Map, a point density Thematic Map, a unique value Thematic Map, a histogram Thematic Map, a pie chart thematic map, grid map thematic map, and so on.

Topic Map rendering is used to display data, which is difficult to represent in a data table. A topic usually uses a certain block or a few pieces of data. You can use data from a data source (such as a local MapInfo table) to add shading to a map with different topics. The topic uses color, fill pattern, or symbol shading to represent data. Topic map display data can be used in multiple ways. You can specify these colors, patterns, or symbols to map objects (based on specific values in the data) to create different topic maps.