Thematic
Overview
Thematic refers to content relating to a specific theme or subject, often used in GIS to describe maps or data layers that focus on particular topics, such as population density, land use, or climate patterns. Thematic maps emphasize spatial variation of one or more attributes rather than showing general geographic features.
Key Concepts
Thematic layer is a data layer representing a specific attribute or phenomenon. Choropleth is a thematic map using color gradients to represent values by area. Proportional symbol uses sized symbols to represent quantitative values. Isoline/Isopleth connects points of equal value (elevation, temperature). Dot density represents quantities using distributed dots.
Thematic Map Types
| Type | Use Case | Example |
|---|---|---|
| Choropleth | Area-based statistics | Population by county |
| Graduated symbol | Point quantities | City populations |
| Heat map | Density/intensity | Crime hotspots |
| Flow map | Movement/connections | Migration patterns |
| Cartogram | Distorted areas by value | Electoral votes |
Appendix
Created: 2025-12-13 | Modified: 2025-12-13