GIS, GPS and Geospatial Technologies for SS 1

Geospatial Technologies

Performance Objectives

By the end of the lesson, students should be able to:

1. define Geographic Information Systems (GIS) and how it works;
2. identify the types of Global Positioning System (GPS) technologies.

Meaning of Geospatial Technologies

Geospatial technologies are modern digital tools used to collect, store, analyze, manipulate and display geographic data related to features on the surface of the Earth.

These technologies allow geographers, planners and scientists to visualize the physical and human features of the Earth in a digital format. By linking location data with descriptive information, geospatial technologies help in making informed decisions about environmental management, urban planning, disaster response and resource allocation.

The three main types of geospatial technologies are:

1. Geographic Information Systems (GIS): Software frameworks used for mapping and spatial analysis.
2. Global Positioning System (GPS): A satellite-based navigation system used to determine precise locations on Earth.
3. Satellite/Remote Sensing: The acquisition of information about the Earth’s surface from a distance using sensors mounted on satellites or aircraft.

Geographic Information Systems (GIS)

A Geographic Information System is a computer-based framework designed to capture, store, manage, analyze and present all types of geographical and spatial data.

Unlike a traditional paper map, which displays static information, GIS is dynamic. It allows users to overlay different layers of information on a single map to reveal patterns, relationships and trends that are not immediately obvious on a flat paper map.

How GIS Works

GIS operates by linking spatial data (where things are) with attribute data (what things are like). The operation of GIS follows a systematic process.

The main stages of how GIS works are:

1. Data Input: Raw geographic data is collected and entered into the GIS software. This data can come from satellite images, GPS coordinates, paper maps that have been digitized, or tabular data such as census records.
2. Data Storage and Management: The system stores the geographic data in digital databases. GIS organizes this data into two primary formats: vector data (points, lines and polygons representing features like water wells, roads and forest boundaries) and raster data (grid cells or pixels representing continuous surfaces like elevation or temperature).
3. Data Manipulation: Before analysis, the collected data is cleaned, scaled and projected onto a uniform coordinate system to ensure that all layers align perfectly.
4. Query and Analysis: Users ask spatial questions of the system. For example, a planner can query the system to find all residential buildings located within 100 meters of a river channel to assess flood vulnerability.
5. Data Output and Visualization: The analyzed data is presented to the user as digital maps, 3D models, charts or reports. These outputs are used by decision-makers to solve real-world problems.

Components of GIS

A functional GIS relies on the interaction of five essential components.

The five components of GIS are:

1. Hardware: The physical equipment needed to run GIS software. This includes high-speed computers, tablets, GPS receivers, scanners for digitizing paper maps, and printers or plotters for map output.
2. Software: The specialized computer programs that provide the tools to input, store, analyze and display geographic information. Examples include ArcGIS, QGIS (an open-source software) and Google Earth Pro.
3. Data: The most critical component of GIS. This includes spatial data (coordinates, boundaries and geographic features) and attribute data (descriptive information about those features, such as the name of a road, the depth of a borehole, or the population of a town).
4. People: The professionals who manage the system. This includes GIS analysts, cartographers, database administrators and urban planners who design, operate and interpret GIS models.
5. Methods and Procedures: The business plans, rules and operating procedures used to address specific spatial problems. This ensures that data collection, analysis and map production follow standardized guidelines.

Global Positioning System (GPS)

The Global Positioning System is a satellite-based navigation system that provides precise location, speed and time information anywhere on Earth.

Originally developed by the United States military, GPS is now globally accessible for civilian, scientific and commercial purposes. It operates continuously under all weather conditions, day and night, and does not require the user to transmit any data to the satellites.

The Three Segments of GPS Technology

GPS technology relies on three distinct parts working together to calculate precise locations.

The three segments of GPS technology are:

1. The Space Segment: This consists of a constellation of at least 24 active satellites orbiting the Earth at an altitude of approximately 20,200 kilometers. These satellites continuously transmit radio signals containing their exact position and the precise time the signal was sent.
2. The Control Segment: This consists of a global network of ground-based monitoring stations, master control stations and ground antennas. These stations track the satellites, update their orbital data, and synchronize their atomic clocks to ensure high accuracy.
3. The User Segment: This consists of the GPS receivers owned by individuals, such as handheld GPS devices, smartphones, vehicle navigation systems and scientific survey equipment. The receiver detects signals from at least four satellites simultaneously to calculate the user’s exact latitude, longitude, altitude and time.

Types of GPS Receiver Technologies

Depending on the required accuracy and the field of application, different types of GPS receiver technologies are used.

The main types of GPS receiver technologies are:

1. Smartphone/Mobile GPS: Built-in GPS chips found in modern mobile phones and tablets. These receivers use Assisted GPS (A-GPS), which combines satellite signals with cellular network data to quickly determine location. They are highly accessible and used for daily navigation, ride-hailing services and social media location tagging.
2. Handheld GPS Receivers: Rugged, portable devices designed specifically for outdoor field activities such as hiking, geological mapping, forestry and agricultural surveys. They are durable, water-resistant, have long battery lives, and operate reliably in remote areas where mobile network signals are unavailable.
3. Vehicle/Navigation GPS: Systems installed in cars, ships and aircraft to assist operators with route planning, real-time traffic updates and navigation. These systems often feature voice-guided directions and pre-loaded road maps.
4. Survey-Grade (Differential) GPS: Highly advanced, expensive GPS systems used by land surveyors, civil engineers and geophysicists. These systems use two or more receivers (a base station and a rover) to correct atmospheric errors, achieving location accuracy down to the millimeter level.

Remote Sensing and Satellite Imagery

Remote sensing is the science of obtaining information about the Earth’s surface from a distance, typically using sensors mounted on satellites, aircraft or drones.

These sensors detect electromagnetic radiation reflected or emitted from the Earth’s surface. The collected data is processed into digital images, known as satellite imagery. Remote sensing provides the raw environmental data, such as forest cover, sea surface temperatures and urban expansion, which is then imported into GIS software for detailed spatial analysis.

Using Digital Tools to Analyze Geographic Information

The integration of GIS, GPS and remote sensing allows geographers to collect and analyze spatial data efficiently. In modern geography, smartphones and tablets serve as powerful digital tools for fieldwork, enabling the collection of real-time coordinates and the visualization of satellite maps.

How to Use a GPS to Locate a Given Coordinate

Locating a specific coordinate on the Earth’s surface is a fundamental skill in fieldwork, navigation and search-and-rescue operations. This procedure can be performed using a dedicated handheld GPS receiver or a smartphone mapping application.

The procedure for using a smartphone GPS application to locate a specific coordinate involves the following steps:

1. Enable the location services (GPS) in the settings menu of the smartphone.
2. Open a digital mapping application, such as Google Maps, QField or a dedicated GPS coordinate finder app.
3. Locate the search bar at the top of the application screen.
4. Enter the target coordinates in decimal degrees format, ensuring the latitude is entered first, followed by a comma, and then the longitude (for example, to locate the National Theatre in Lagos, Nigeria, enter: 6.4761, 3.3686).
5. Tap the search or enter button on the keyboard to initiate the search.
6. Observe the marker pin that appears on the map, which indicates the exact location of the entered coordinates.
7. Switch the map view to “Satellite” or “Terrain” mode to analyze the physical features, vegetation and buildings surrounding the located point.
8. Use the zoom-in and zoom-out functions to study the spatial relationship of the coordinate point with nearby landmarks.

Summary of Geospatial Technologies

The table below summarizes the differences and relationships between the three main geospatial technologies.

Evaluation Questions

Use the following questions to assess understanding of the topic:

1. Define Geographic Information Systems (GIS) and list its five main components.
2. Explain the four major stages involved in how a GIS works.
3. Identify and describe the three segments of Global Positioning System (GPS) technology.
4. State three differences between handheld GPS receivers and survey-grade GPS receivers.
5. Describe the step-by-step procedure for using a digital mapping tool to locate a given coordinate.