Understanding the Technology That Maps Our World
Have you ever wondered how your navigation app finds the fastest route home, how weather forecasters predict the path of storms, or how cities decide where to build new developments? Behind these everyday uses, and many others, lies a powerful technology called Geographic Information Systems, or GIS.
At its heart, GIS is simply a technology that captures, analyses, and displays data linked to locations. While that might sound technical, the concept is actually quite straightforward: GIS helps us understand information, by putting it on a map.
Think about it – almost everything in our world has a location.
Your home, your workplace, the restaurants you visit, the roads you use, and the places you go to relax, all exist somewhere specific on Earth. But location matters for much more than just buildings and places. Weather patterns, wildlife populations, disease outbreaks, customer preferences, and countless other types of information all have an important geographic component.
This location element, inherent in ~80% of the data we use, is incredibly powerful.
When we take data – whether it’s census figures, sales numbers, temperature readings, or traffic counts – and map it, something magical happens.
Patterns emerge. Connections become visible. And new stories unfold.
How GIS Maps Help Everyone: Simple Examples
Maps have always helped us understand our world, but modern Geographic Information Systems (GIS) take mapping to a whole new level. These powerful tools don’t just show us where things are – they help us solve real problems that affect our daily lives, often without us even realising it.
When you use your phone to find the quickest route home, check a weather forecast, or look for nearby restaurants, you’re benefiting from GIS technology. Behind the scenes, GIS supports critical decision-making across numerous industries – for example helping your city plan better transport, helping businesses identify where to open new facilities, and ensuring emergency services can prepare for floods or other disasters, and can respond quickly if they occur.
Understanding Patterns in Places
At the most basic level, GIS helps us see where things are located. But simply by mapping things we can start to identify patterns in their spatial distribution. For example, health professionals can use mapping during disease outbreaks to see where cases are clustering, helping them identify potential causes and focus efforts on containment. Business owners might map where their customers are coming from to decide where to open new locations. Environmental campaigners or park rangers might map sightings of endangered species to help understand how to support habitats. In these ways maps can turn complicated information into clear pictures that help people make better decisions.
Figuring Out What’s Nearby
GIS helps answer questions about what’s close to what, and how easily people can get to important places. For example, regional planners use GIS to help ensure that local populations have sufficient access to key services such as schools and hospitals, transport planners use it to make sure neighbourhoods are well-connected to transport networks, while emergency services use it to check their assets are located to reach incidents as quickly as possible. These tools go beyond just measuring straight-line distances but can also consider real-world factors like road speeds and physical barriers such as rivers and mountains to show true accessibility.
Finding the Best Locations
When we need to decide where to put something new, GIS can help us weigh all the important factors that will influence that decision. For example, solar energy developers use GIS to find the sunniest spots that are also close to power lines and away from sensitive environmental constraints. Manufacturers will use GIS data to assess where to locate new factories, warehouses or distribution centres so that they are close to input materials or onward transport connections. Similarly, when moving house people can use GIS to understand important factors like the proximity of schools or open space. By combining data on many different factors into easy-to-understand maps, GIS helps make it much easier to identify the best options.
Seeing How Different Factors Relate to Each Other
GIS can help us understand relationships between different things that happen in the same places. For example, health researchers might examine whether neighbourhoods with worse air pollution have higher asthma rates, while businesses might study how geo-demographic characteristics relate to buying behaviour. Rather than just guessing about these relationships, GIS provides tools to measure and verify connections, helping people make decisions based on real evidence rather than assumptions.
Understanding How Things Flow and Connect
GIS can also help us see how people, water, electricity, and other things move through natural or infrastructure systems. Transport planners use GIS to understand traffic flows to reduce congestion and plan better transport networks. Utility companies map pipes, wires and flow data to quickly find and fix problems. Water quality experts track how pollution travels downstream through rivers and waterways. These applications and many more help us understand connections between places and find the best paths from one point to another.
Watching How Things Change Over Time
As well as linking data to location, GIS also lets us track changes to places over days, months, years, or decades. For example, climate scientists track temperature changes across regions to understand climate patterns, historians use GIS to show how civilisations have developed and declined over centuries, and environmental planners will monitor a range of changes such as coastal erosion or air quality to understand how conditions are changing over time. By adding time to maps, GIS reveals important trends and patterns of change, helping us understand not just how things are today, but how they’re changing and what might happen next.
Exploring Height and Depth
Modern GIS can even go beyond flat maps to include information about height, depth, and volume. For example, planners can create 3D models of new buildings and developments to see how they’ll affect skylines and shadows, while weather forecasters can also model storms in three dimensions. By combining further dimensions with location data, GIS can help us better understand our world more fully, moving beyond flat maps to represent it more completely.
What does a GIS system do?
How GIS Organizes Our World: Understanding the Building Blocks
When you look at a beautifully designed map showing everything from neighbourhood boundaries to the location of your favourite coffee shops, you might not realise just how cleverly GIS organises all that information. Think of GIS as a digital layer cake, with different types of geographic information stacked together to create a complete picture. Let’s look “under the hood” to see how GIS structures data to represent our complex world.
Basemaps: The Foundation Layer
Every good map needs context, and that’s where basemaps come in. These are the background maps that provide reference information for whatever specific data you’re looking at.
A basemap will often include key information that contextualises everything else you want to add for example:
- Place names
- Borders
- Coastlines and waterways
- Streets and highways
- Buildings and landmarks
- Other features of the landscape such as hills and valleys
Think of the basemap as the canvas on which you paint your specific information. When you open Google Maps or Apple Maps, you’re looking at a basemap. Then, when you search for “coffee shops near me,” those points of interest appear on top of the basemap.
Points on the Map: The Simplest Building Block
The most basic element in GIS is the humble point – a single location marked by coordinates (typically latitude and longitude). Points are perfect for representing specific places like:
- The exact location of an asset such as a telephone mast
- A point of interest such as your favourite restaurant
- A data point such as a bird sighting in a conservation area
- Or a key element within a wider network such as a bus stop or railway station
Points may be simple, but they’re incredibly powerful. Your satnav, for instance, treats your destination as a point, calculating the best route to that exact spot. Emergency services use points to pinpoint exactly where help is needed. And every time you check-in somewhere on a social media app, you’re essentially creating a point on a map.
Lines and Shapes: Connecting the Dots
While points show us where things are, lines and polygons (shapes) show us how things connect to each other and what areas they cover:
Lines represent features with length but little width, such as:
- Roads and highways
- Rivers and streams
- Walking paths
- Utility networks
- Flight paths
Polygons are enclosed shapes that represent areas with boundaries, such as:
- The extent of your neighbourhood or city
- A lake or park
- A property development site
- The catchment area for a school
- Conservation areas or habitats
When an insurance company assesses flood risk, they’ll use polygon data to map flood zones. Similarly, when governments organise elections they’ll publish detailed polygons setting out the electoral boundaries that determine how votes will be aggregated. Data represented in lines and polygons enables us to take our understanding of locations to the next level.
Raster Layers: The World as a Grid
Not everything fits neatly into points, lines, and polygons. Some information is continuous across the landscape, changing gradually from one location to the next. For this, GIS uses another form of data – raster data. A raster is essentially a grid of cells, with each cell containing a value. Raster data is particularly useful for visualising aerial or satellite images continuously on a map by linking images to their exact physical locations. Using a grid can also be very useful to get complete coverage of an area without any gaps and is often the preferred file type for modellers.
Data Uses of Raster Layers: Raster data can be ideal for representing a whole range of continuous geographic information such as:
- Elevation models showing the height of every point
- Temperature maps where each cell shows the temperature at that location
- Rainfall data showing precipitation amounts across a region
- Tree canopy coverage showing what percentage of each cell is covered by trees
Raster data is perfect for use in modelling natural phenomena. When meteorologists track a storm system or ecologists monitor changes in forest health, they’re most likely working with raster data.
Geolocating Images: Raster data is especially important for bringing maps to life in other ways, in particular by enabling users create new types of maps using images. For example, raster data can be used to present satellite imagery, ensuring that the positions of the image are perfectly linked to the locations on the map.
Adding the Fourth Dimension: Time
Our world isn’t static – it’s constantly changing. Modern GIS systems embrace this by incorporating time as another dimension. This enables us to add time to maps helping see how places change over time for example:
- Investigating traffic patterns that change throughout the day
- Identifying seasonal variations in wildlife
- Visualising changes in land use over time
- Monitoring and predicting weather systems
- Understanding population and migration flows, and many more
Time-enabled GIS allows us to press “play” on our maps and watch how patterns evolve.
GIS Databases: Not Your Average Spreadsheet
By organising our world into these digital building blocks – points, lines, polygons, rasters, and time series – GIS helps us make sense of our complex planet. GIS databases enable us to bring together these distinct building blocks that we can add and interrogate as layers to understand places in deep levels of granularity.
Unlike other types of databases that might just store names and numbers, GIS databases:
- Store complex geometric information about shapes and locations
- Handle different coordinate systems (there are more than you might think)
- Understand spatial relationships (like which points fall within which polygons)
- Enable efficient searches based on location (for example querying the data to “find all parks within 50 miles of the Eiffel Tower”).
These specialist “spatial databases” perform enable many of the processes needed to understand our world by making it easy to work with geospatial information.
What sorts of insights can you get from a GIS system?
Seeing What Numbers Can’t Tell Us: Insights from Mapping
Once we’re using geospatial data and geospatial databases we’re in a position to create new insights. By putting data on a map, patterns emerge, relationships become visible, and stories unfold. This visual transformation is where GIS truly shines, turning abstract numbers and coordinates into meaningful insights that anyone can understand at a glance.
In this section we’re going to explore the different ways GIS help visualise data and the unique insights each approach can provide.
Point and Icon Maps: Spotting Clusters and Coverage
What they are: The simplest map visualisations place points or icons at specific locations. Each dot or symbol represents something happening at that exact spot – a business, an event, a facility, or an observation.
Insights revealed: Point maps excel at showing distribution patterns, clusters, and gaps. They answer questions about where things are happening and whether they’re concentrated in certain areas.
Real-world examples:
- Public health workers might map disease cases to identify outbreak clusters and potential transmission hotspots.
- Business analysts might map customer locations to see where their clients live and work, revealing market penetration and gaps.
- Wildlife researchers might plot animal sightings to discover and movement patterns.
The example below visualises each individual building within the Brickhill area of Bedford, UK using data provided by Ordnance Survey. By visualising each property as a point the edges of the settlement area and structure of individual neighbourhoods becomes clear.
Category Maps: Understanding Types and Diversity
What they are: Category maps use different colours or symbols to show different types of features. Rather than just showing where things are, they show what kind of things are where.
Insights revealed: These maps reveal patterns in how different categories are distributed, showing whether certain things are concentrated in specific areas or mixed throughout a region.
Real-world examples:
- Land use maps show which areas are residential, commercial, industrial, or green spaces.
- Soil type maps help farmers understand the different agricultural grades of land.
- Point of interest maps colour-code different types of attractions potentially revealing patterns or opportunities.
The example below shows different types of land use in Plymouth, UK by assigning different colours to polygons based on the different categories of use within each area.
The example below provides a map of potential heat sources in the UK by using different icons for each heat source type.
Choropleth Maps: Comparing Areas by Intensity
What they are: These familiar maps use colour shading to show how a value varies across defined areas like counties, neighbourhoods, or countries. Darker colours typically represent higher values while lighter values typically represent lower values.
Insights revealed: Choropleth maps excel at showing patterns across regions, highlighting which areas have higher or lower values for a particular measure and revealing geographic disparities.
Real-world examples:
- Census data maps showing population density across neighbourhoods
- Election maps displaying voting results by area
- Public health maps depicting vaccination rates by county
- Economic maps illustrating income levels across regions
The example below shows the population density of all the settlements in Somerset, UK. Each county in the UK can be sub-divided into different official zones which can then be used to collect and present data. Within GIS we can assign a colour to each of these zones so that the patterns in the data start to emerge. In this example by mapping population density to each zone we can clearly see the patterns of the major towns and their and their respective densities.
The example below uses a similar process to show the most and least derived areas across the UK.
Finally, the map below shows the 2023 population by state in the US.
Proportional Symbol Maps: Understanding Magnitude
What they are: These maps use differently sized symbols (often circles or icons) where the size represents the quantity of something at that location. Larger symbols indicate larger values.
Insights revealed: Proportional symbol maps show both location and magnitude simultaneously, making it easy to identify not just where things are happening, but how significant they are.
Real-world examples:
- Earthquake maps where circle size represents magnitude
City maps where circles represent population size - Business maps where symbols represent store sales volume
- Traffic maps where line thickness represents vehicle count
The map below shows different types of renewable generation infrastructure within South Oxfordshire, UK. In this map the size of each circle is proportional to the capacity of each generating asset.
Contour Maps: Revealing Gradual Changes
What they are: Contour maps use lines to connect points of equal value, similar to the elevation lines on a hiking map. Each line represents a specific value, with lines closer together indicating steeper changes.
Insights revealed: These maps excel at showing how values gradually change across a landscape, revealing peaks, valleys, and gradients that might be invisible in raw data.
Real-world examples:
- Topographic maps showing elevation changes
Weather maps displaying differences in pressure - Pollution maps showing concentration gradients
- Groundwater maps showing aquifer depths
The fainter lines on the map below show the contours and elevation of the landscape around Lake Windermere in the Lake District, UK.
Heat Maps: Finding Intensity Hotspots
What they are: Heat maps (sometimes called density maps) use colour gradients to show concentration intensity. They transform individual points into smooth surfaces showing where points cluster most densely.
Insights revealed: Heat maps are great for revealing hotspots and patterns from many individual data points, making them perfect for finding where activities often concentrate.
Real-world examples:
- Crime analysis maps showing the concentration of incidents or anti-social behaviour
- Retail maps displaying customer footfall, highlighting points where footfall is highest
- Wildlife tracking maps showing animal activity hotspots
- Social media maps showing where topics are trending
The example below shows a heatmap of road collisions in the city of Cambridge, UK between 2005 and 2020. This visualisation clearly shows the clustering of collisions along key streets and junctions such as the junction at Newmarket Road.
Desire Lines: Understanding Movement Flows
What they are: Desire line maps show movement between origins and destinations with lines connecting points. Thicker lines typically represent higher volumes of movement.
Insights revealed: These maps help us understand movement patterns and connections between places, revealing where there is high demand for movement.
Real-world examples:
- Transportation maps showing the flows of commuters between residential and employment locations
- Migration maps showing the population movements between countries
- Trade maps showing import/export relationships
- Communication maps illustrating call or data transfer volumes between cities
The example below shows the morning commuter flows between zones in Oxford, UK, showing where workers start and end their journeys. In this example the width and the colour of the lines both change in proportion to the volume of movement helping highlight where travel demands are greatest.
The example below shows how desire lines can be combined with proportional symbol maps to further highlight the popularity of different travel destinations, in this case across an entire region.
Isochrones: Visualizing Access and Reach
What they are: Isochrone maps show how far you can travel from a starting point within a given time. They create irregular shapes around locations based on the actual travel times experienced rather than simple distance.
Insights revealed: These maps transform our understanding of accessibility by showing reach based on time rather than distance, accounting for real-world factors like traffic speeds and natural or physical barriers.
Real-world examples:
- Transport maps showing areas reachable within 30 minutes by public transportation
- Emergency response maps displaying how quickly services can reach different parts of a city or region
- Retail maps illustrating how long it will take customers to drive to different store locations
- Employment opportunity maps showing the number of jobs reachable within a reasonable commuting time.
The example below shows how far you can travel within 45 minutes by Electric Bicycle from Epping High Street in Essex, UK. Isochrones like this can be used to help compare how easy it is to get to different locations using different modes of transport – for example comparing bikes to e-bikes or cars to public transport.
Conclusion: The Power of Geospatial Visualisation
The diverse visualisation techniques offered by GIS systems transform abstract data into compelling spatial narratives that reveal patterns, relationships and insights impossible to discern from raw numbers alone. Each method – from simple point maps to sophisticated isochrones – serves a unique analytical purpose, helping us understand not just where things are happening, but why they matter. As you apply these methods to your own projects, remember that effective mapping isn’t about creating the most complex visualisation – it’s about choosing the right technique to bring to life the data relevant to your specific questions and communicate insights that numbers alone cannot reveal.
Mapping the Future with GIS
Throughout this exploration of Geographic Information Systems, we’ve journeyed from understanding the fundamental building blocks of spatial data to discovering the powerful visualisation techniques that can help you bring information to life. At its core, GIS represents a profound shift in how we perceive our world – transforming abstract coordinates and datasets into meaningful understanding that can reveal the hidden patterns shaping our world. GIS has become an essential lens through which to understand and navigate increasingly complex data by putting it in a context that everyone can make sense of – a map.
As GIS technology continues to evolve – incorporating richer data sources, more sophisticated analytical tools, and increasingly intuitive interfaces – its transformative potential is only going to grow. Whether you’re just beginning your journey with GIS or looking to deepen your expertise, consider how the spatial tools we’ve reviewed in this blog might help you tell compelling stories with your data, uncover relationships that numbers alone can’t express, or simply make better decisions about the places that matter to you and your organisation.