1.Geographic Information Systems 2.Global Positioning System 3.Aerial Photographs 4.Satellite Imagery
Geographic Information Systems A geographic information system (GIS) is the newest kind of mapping technology GIS integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.
Why Use It? GIS software allows you to do the following: Mapping - create and manipulate symbols and colours to create an output map Query - allows you to ask questions such as: where is …? What’s the nearest ….? What intersects with …? Select - identify features and their attributes Distance - calculates distance between features Overlay - displays multiple layers of information at one location Merge - combines multiple layers into one layer 3-D - data can be viewed with height in 3-dimensions for powerful viewing
Who uses GIS? Forestry - inventory and management of resources Police - crime mapping to target resources Epidemiology - to link clusters of disease to sources Transport - monitoring routes Utilities - managing pipe networks Oil - monitoring ships and managing pipelines Central and local government - evidence for funding and policy Health - planning services and health impact assessments Environment agencies - identifying areas of risk - flood Geographic Information Systems
Who uses GIS? Emergency departments - e.g. ambulance Retail - store location Marketing - locating target customers Military - troop movement Mobile phone companies - locating masts Land registry - recording and managing land and property Estate agents - locating properties that match certain criteria Insurance - identifying risk e.g. properties at risk of flooding Agriculture - analyzing crop yields
Global Positioning System The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS.
Global Positioning System How it works GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and calculates the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map. These satellites send radio signals to Earth that contain information about the satellite.
Three distinct parts make up the Global Positioning System. The first segment of the system consists of 24 satellites, orbiting 20,000 km above the Earth in 12-hour circular orbits. This means that it takes each satellite 12 hours to make a complete circle around the Earth. In order to make sure that they can be detected from anywhere on the Earth's surface, the satellites are divided into six groups of four. Each group is assigned a different path to follow. This creates six orbital planes which completely surround the Earth. The satellites travel at speeds of roughly 7,000 miles an hour.GPS satellites are powered by solar energy. They have backup batteries onboard to keep them running in the event of a solar eclipse, when there's no solar power. Small rocket boosters on each satellite keep them flying in the correct path.
Satellite Imagery Satellite images are also pictures of the Earth taken from above, but these electronic images (instead of photographs) cover very large areas but show less detail. –Landsat was developed by the Americans and uses sunlight and heat reflected from the Earth’s surface to create images –SPOT was developed by the Europeans and similar to Landsat, but it can create 3D images of the surface –RADARSAT was developed by the Canadians and uses radar signals (or microwaves) instead of sunlight and heat, so it can be used at any time of day or night