Understanding Map Types in GIS Cartography
Maps
Welcome to the world of modern cartography! Before we dive into creating compelling visuals and running complex spatial analyses, we must start with the foundation: the map itself. At its core, a map is a powerful tool for communication, a blend of science and art that allows us to see the world in new ways.
In this guide, we will explore a specific framework for classifying maps: Study Area, Site, Thematic, and Analytic. This system is designed for the practical GIS user, aligning with the daily workflow of data analysis and presentation.
What Exactly is a Map?
A map is a symbolic, scaled-down representation of reality. It's a model that tells a story about a location. The four fundamental concepts of map-making are:
- Scale: The ratio of distance on the map to distance on the ground.
- Projection: The method of transferring locations from the Earth's 3D surface to a 2D plane.
- Symbolization: The visual language of symbols used to represent real-world features.
- Generalization: The process of simplifying and selecting information to display on the map.
Ancient Beginnings (c. 600 BCE)
The Babylonian Map of the World, a clay tablet, is one of the oldest known world maps.
The Greeks & Scientific Cartography (c. 500 BCE - 200 CE)
Ptolemy’s "Geographia" established the concepts of latitude and longitude.
The Age of Exploration (15th - 17th centuries)
Gerardus Mercator’s 1569 world map was a revolutionary tool for sailors.
The Thematic Revolution (19th century)
Dr. John Snow's map of cholera cases in London proved the power of spatial analysis.
Meet the Map Makers
- Surveyors: The "ground truthers" who take exact measurements of land.
- Cartographers: The "visual storytellers" who are experts in map design.
- GIS Analysts: The "data scientists of space" who analyze spatial data.
Types of Maps
Choosing the right type of map is the first step in effective spatial communication. This chapter introduces the four core types of maps for GIS professionals.
1. Study Area Map (Overview)
An "establishing shot" to orient your audience. Provides geographic context on a small scale.
2. Site Map (Detailed Zoom-In)
A "close-up" for a specific location, showing precise boundaries and features on a large scale.
3. Thematic Map (Specialized Outputs)
A "spotlight" on a single subject, visualizing the distribution of a specific dataset.
4. Analytic Map (Spatial Data Results)
The "conclusion" of your story, displaying the results of a spatial analysis or model.
Choosing the Right Map
| If your primary goal is to... | Then you need a... |
|---|---|
| ...orient your audience to your area of interest? | Study Area Map |
| ...show precise boundaries and engineering details? | Site Map |
| ...visualize the pattern of a single dataset? | Thematic Map |
| ...present the result of a model to make a decision? | Analytic Map |
Requirements for Map Making
A map is constructed from raw information. This chapter covers what that data looks like, where it comes from, and how to choose the right "ingredients" for your map.
Data is the Heart of Every Map
- Vector Data: Uses points, lines, and polygons to represent features with clear boundaries.
- Raster Data: Uses a grid of cells (pixels) to represent continuous phenomena like temperature or elevation.
- Attribute Data: Information about the features, stored in a table.
Primary Data Collection (Creating it yourself)
Gathering data firsthand through field surveys or remote sensing (satellites, drones).
Secondary Data Collection (Using data from others)
Using data that someone else has already created, often from Open Data Portals.
