1.1 What is GIS, GIS concepts, spatial thinking
What is Geographic Information Systems?
Geographic Information Systems (GIS) is a technological field that incorporates geographical features with tabular data in order to map, analyze, and assess real-world problems. The key word to this technology is Geography – this means that the data (or at least some portion of the data) is spatial, in other words, data that is in some way referenced to locations on the earth. Coupled with this data is usually tabular data known as attribute data. Attribute data can be generally defined as additional information about each of the spatial features.
It is the partnership of these two data types that enables GIS to be such an effective problem solving tool through spatial analysis.
Components of GIS:
- Hardware
- Software (including web software),
- Data
- geodatabases are grouped into two different types: vector and raster;
- attribute data,
- metadata (documentation of GIS dataset))
- People
Spatial Thinking
Spatial thinking is the cognitive ability to understand patterns, relationships, and processes in space. GIS concepts formalize this thinking through spatial data models, projections, analysis tools, and visualization methods. Together, they allow us to answer complex “where” questions and make informed, location‑based decisions.
GIS concepts and spatial thinking are the intellectual foundation of all GIS work. They explain how we understand space, why location matters, and what makes spatial data fundamentally different from other data.
Spatial thinking is the ability to understand relationships, patterns, and processes in space. It includes imagining transformations, visualizing relationships, and using space as a framework for reasoning.
1.2 Vector vs raster
| Feature | Vector | Raster |
|---|---|---|
| Data Type | Discrete | Continuous |
| Structure | Coordinates (points/lines/polygons) | Grid of cells (pixels) |
| Best For | Roads, parcels, boundaries | Elevation, temperature, imagery |
| Precision | High | Depends on resolution |
| Storage Size | Smaller (simple geometries) | Larger (high-res imagery) |
| Analysis Speed | Slower for overlays | Faster for surface analysis |
| Software Use | ArcGIS, QGIS vector tools | Remote sensing, raster tools |
Combine both in hybrid workflows (e.g., overlaying vector parcels on raster elevation). Use vector for infrastructure, administrative zones, and discrete features. Use raster for terrain modeling, environmental gradients, and satellite imagery.
There are three fundamental vector types: Points, Lines, Polygones.
map scale, resolution
When a raster represents the elevation of the ground, it is called a digital elevation model (DEM). If it also includes non-ground objects such as buildings and trees, it is called a digital surface model (DSM).
Continuous Data (raster), Discrete Data (raster)
Topology
1.3 Coordinate systems, projections, datums
A coordinate system defines how locations on Earth are measured and represented.
A projection is the mathematical method used to flatten the curved Earth onto a flat surface.
A datum defines the shape of the Earth and the origin point for measurements.
Coordinate Systems (CS): There are two major types
| Geographic Coordinate Systems (GCS) | Projected Coordinate Systems (PCS) |
|---|---|
| Based on a 3D spherical model of Earth Units: degrees (latitude, longitude) Example: GCS WGS 84 Good for: global datasets, GPS Not good for: accurate distance/area calculations | Based on a 2D flat map Units: meters or feet Example: UTM Zone 17N, NAD83 / Ontario MNR Lambert Good for: measurement, analysis, mapping at local/regional scales |
Key idea:
GCS = where things are on the globe
PCS = how we flatten the globe to measure things accurately
A projection is the mathematical method used to flatten the curved Earth onto a flat surface. Every projection distorts something: Shape, Area, Distance, Direction. You can’t preserve all four at once.
Common projection families:
| Conformal (preserve shape) | Equal‑area (preserve area) | Equidistant (preserve distance) | Compromise (balance distortions) |
|---|---|---|---|
| Mercator, Lambert Conformal Conic – Used for: navigation, mid‑latitude regions (e.g., Canada) | Albers Equal Area, Mollweide – Used for: environmental analysis, land cover, climate data | Equidistant Conic – Used for: radio ranges, distance buffers | Winkel Tripel – Used for: world maps |
Key idea:
Choose a projection based on what you need to preserve.
A datum defines the shape of the Earth and the origin point for measurements. It’s the underlying mathematical model that supports a coordinate system. Two main types:
| Geocentric (Earth-centred) | Local datums |
|---|---|
| WGS 84 (used by GPS) NAD83 (North America) | NAD27 (older North American datum) ED50 (Europe) |
Why datums matter:
Different datums = different coordinate values
Even for the same location, coordinates can shift by tens to hundreds of meters.
0°00’00.0″N 0°00’00.0″E – “Null Island”
1.4 Map design, symbology, classification
1.5 Layouts, typography, cartographic standards
| References & Resources |
|---|
| PennState College of Earth and Mineral Sciences. GEOG468 GIS Analysis and Design PennState College of Earth and Mineral Sciences. GEOG468 GIS Analysis and Design An Introduction to Geospatial Thinking and Open Source GIS by Jennifer Moore, Chapter 1 LinkedIn, What are some of the key concepts and principles of spatial thinking and analysis that underpin GIS? ArcGIS StoryMaps, Review: Geography, Spatial Thinking, & Geospatial Technology Geoinfotech, The Power of Spatial Thinking: How GIS Drives Smart Decision-Making Across Sectors – Geoinfotech Vector vs Raster in GIS: What’s the Difference? – GIS Geography Types of GIS Data Explored: Vector and Raster – Geography Realm Vector Data vs Raster Data: Key Differences Vector vs Raster Analysis: A Comprehensive Comparison – Spatial Eye 9 Vector vs Raster Data Approaches That Transform Digital Maps – Map Library AI-Generated content |