What is GIS GIS How does a GIS work ? Other Digital Data Satellite Data Aerial Photographs Digital Maps New Information Other Digital Data Tabular Information GIS

What is GIS “Geographic Information System”? A geographic information system (GIS) uses computers and software to control the fundamental principle of geography—that location is important in people’s lives. GIS combines layers of information about a place to give you a better understanding of that place. What layers of information you combine depends on your purpose — finding the best location for a new store, analyzing environmental damage, viewing similar crimes in a city to detect a pattern, and so on. Why is this layering so important? The power of a GIS over paper maps is your ability to select the information you need to see according to what goal you are trying to achieve. A business person trying to map customers in a particular city will want to see very different information than a water engineer who wants to see the water pipelines for the same city. Both may start with a common map—a street and neighborhood map of the city but the information they add to that map will differ. Integrate data in various formats from many sources using GIS.

The Basic Of GIS What is a GIS? The short history of GIS (it goes back to the late 1960's) was founded in attempts in the UK, Canada and US to automate some of the land-management and census activities of government. Figuring out how to do that, and how to explain what went wrong when they tried, was the start of the science of GIS. It was realized that many map-related concepts that seem so simple to us (scale, a boundary), required a lot of effort to teach to a computer. What is a GIS? The name says it all, but we have to understand the implications of the words in the name.

GIS and Related Software

GIS concepts are not new! London cholera epidemic 1854 Cholera death Water pump Soho + GIS concepts are not new! The concepts used in GIS are not new to Geographers. In the purest sense Geographers have made use of such systems for many years, but these have been manually operated - card indexes with paper map overlays, atlases and similar systems. The following is one example: In the London Cholera epidemic of 1854 Dr. John Snow was able to locate the source of the the outbreak by plotting the locations of fatal cases. Kingston Centre for GIS

Spatial information handling 1854 Cholera death Water pump Soho + The location of cholera cases and the position of the water pumps in Soho, London 1854 John Snow found that there was a concentration of some 500 cases within a few hundred yards of one particular public water pump on Broad Street, Soho. Snow was able to prove this: when the pump handle was removed, no new cases were diagnosed in that Street. He proved that the pump had been the source of the those cases and that the cholera was carried in the contaminated water. Kingston Centre for GIS

1.2. History of GIS Prior to 1960 GIS’s origins lie in thematic cartography. Many planners used the method of map overlay using manual techniques. The 1960s and 1970s Many new forms of geographic data and mapping software. First GIS developed in Canada for land use inventory. Development of the first computer cartography packages for mainframe computers. First remote sensing images. Mathematical Models.

The 1980s and 1990s First commercial GIS Packages. Diffusion of Microcomputers. Integration with other software (mainly CAD and databases). US Census Bureau efforts in the 1980s: Digitize spatial, economic and demographic attributes of the United States. Creation of the TIGER format (Topologically Integrated Geographic Encoding and Reference ). The 2000s Integrated Information technologies with geography. Powerful applications on desktop computers. Web/network based data sources. Portable and inexpensive field GISs with GPS capabilities.

Layers representing the real world 1.2 GIS Main Concepts This section covers the two basic GIS concepts you need to know to effectively use any GIS maps GIS Concept #1: Features have attributes associated with them. Imagine a tree. How would you keep track of and communicate information about this tree to other people who need to know all about it? You might use a database to keep track of what species it is, how old it is, how tall it is, how healthy it is, and any other attributes that are important. This tree is one record in a database. We call each category (i.e. tree height) a field. Now imagine a grove of trees that you need to keep track of attributes for. Because we are now dealing with more than one tree, it becomes relevant where each tree is so we know what information relates to which tree Layers representing the real world

GIS Concept # 2: Information is separated into layers. We map the location of each tree and identify which attributes belong to which tree. This is the foundation of GIS. A GIS tells us where some is. Computers are synonymous with GIS, and using a computer we can have hundreds of fields (different attributes) for millions of records (trees). GIS Concept # 2: Information is separated into layers. We can also have other layers of information in our GIS. Our infor-mation on trees would constitute one layer of information. We could also have a layer with rivers and a layer with soil types. Any information can be represented as a layer A map represents the landscape in an artificial way. Vector layers represent features in one of several ways: Points: A point is good for representing information in which it is necessary to show where a feature is, but its physical shape is not important (i.e. trees in the old growth tree layer). Lines: A line is suitable to represent many real world features (i.e. the rivers in the river layer). Polygons: Don't be intimidated by the name. It is really just a solid multi-sided shape. When you see a polygon, remember that everything inside the boundary has the attributes associated with the record. (i.e. soil types in the soils layer)

Maps are Composed of Layers States Rivers Lakes Roads Capitals

You might hear people talk about coverage, Geodatabase, or shapefile You might hear people talk about coverage, Geodatabase, or shapefile. All these terms are other names for layers of information. With individual layers we can conduct analysis between layers and only display layers of interest How GIS deals with layered data? GIS takes the numbers and words from the rows and columns in databases and spreadsheets and puts them on a map. Placing your data on a map highlights where you have many customers if Combining attributes and Geometry in GIS you own a store, or lots of leaks in your water system if you run a water company. It allows you to view, understand, question, interpret, and visualize your data in ways simply not possible in the rows and columns of a spreadsheet. And, with data on a map, you can ask more questions. You can ask “Where?,” “Why?,” and “How?,” all with the location information on hand.

1.3. GIS Functions Data Input & Management Spatial Attribute Quality Control & Database Management Data Manipulation: Geo-processing Analysis & Modeling Information Output Maps, charts, tables, reports …

Basic Structure of a GIS Data Input Query Geographic Database Output: Display Transformation and Analysis

Database Management System Spatial Data Modeling Visualization Spatial Analysis & Spatial modeling Spatial Data & Attribute Data A geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on Earth. GIS technology integrates common database operations such as query and statistical analysis with the unique visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable to a wide range of public, military and private enterprises for explaining events, predicting outcomes, and planning strategies. Whether siting a military base camp, finding the best soil for a tank to maneuver on, or figuring out the best low level air route for a bombing raid. Map making and geographic analysis are not new, but a GIS performs these tasks better and faster than do the old manual methods. And, before GIS technology, only a few people had the skills necessary to use geographic information to help with decision making and problem solving. Today, GIS is a multi-billion-dollar industry employing hundreds of thousands of people worldwide. GIS is taught in schools, colleges, and universities throughout the world. Professionals in every field are increasingly aware of the advantages of thinking and working geographically. Database Management System

Data Input Scan Digitize GPS Digital Elevation Model Air Photos Satellite Imagery Tiger/Line Transformation Transformation

Output Information Output Maps Charts Reports

Triad of Geography Where How? Why? When What Where: locations When: time What: things  properties/attributes

GIS Applied: Two Big Questions Where is what? Obtain information from a location What is where? Query information to find location