Reading Discussion

Computer Language ► Computers understand strings of zeros and ones, making it difficult to comprehend how maps and other geographical images are able to be represented in digital form. ► It is important to understand that digital representation of geography is not equal to geography itself, and always involves a certain degree of approximation or estimation. ► Without getting too detailed, what kind of techniques or methods could be used to process geographical information in a beneficial way?

Methods created for processing geographical information ► Since the mid-1970’s  Techniques to input geographical information, converting the information to digital form  Techniques for storing such information in compact format on computer disks, compact disks, and other digital storage media  Methods for automated analysis of geographical data, to search for patterns, combine different kinds of data, make measurements, find optimum sites or routes, and a host of other tasks  Methods to predict the outcome of various scenarios, such as the effects of climate change on vegetation  Techniques for display of data in the form of maps, images, and other kinds of displays  Capabilities for output of results in the form of numbers and tables

Geographical Information Systems ► Also known as GISs ► Encompasses wide range of geographical data; includes GIS data, GIS decisions, and GIS systems ► Complex systems that can take months or years to set up ► How do they work?

GIS Pyramid ► The decision-making pyramid is one technique used to analyze and simplify data ► Uses a “layered” method of projecting data ► One layer superimposed over the existing layer below ► GIS are now in the process of filling the upper half of the pyramid

GIS Chain ► GISs are complex systems made up of several interconnecting parts ► GISs cannot be “bought of the shelf” but rather must be built within an organization ► Careful attention must be paid to all links of the chain ► There is a distinct difference between GPS (global positioning systems) and GIS, but do you think that a hand- held GPS/navigation device can be considered a GIS? After all it can be “bought off the shelf”.

Maps ► Traditionally geographical data was presented on maps ► A legend would be present on the map describing the meaning of the symbols used on the mapped area ► Effective in storing and presenting geographical data ► Ineffective in manipulating data and altering the presentation ► Usually made for a particular purpose

Advantages of GIS over maps ► Data storage and data presentation are separate  Allows data to be presented and viewed in various ways ► Once data is stored we can  Zoom in or out  Display selected areas  Make calculations and correlations  Create and present tables displaying desired details on the map  Superimpose the map on other information  Search demographics for best location for retail stores! Anything else?

Components ► There are many definitions of geographical information system, for now consider a GIS to be any computer-based capability for the manipulation of geographical data ► Includes hardware, software, special devices used to input maps and create map products, and communication systems needed to link various elements

Hardware and software functions include:  Acquisition and verification  Compilation  Storage  Updating and changing  Management and exchange  Manipulation  Retrieval and presentation  Analysis and combination Now do you consider a GPS device a GIS? Now do you consider a GPS device a GIS?

Georeferencing ► All data in a GIS are georeferenced to a specific location on the surface of the Earth through a coordinate system ► Common coordinate system is that of longitude and latitude, however many other systems exist ► GIS must be capable of transforming georeferences from one system to another ► Can a GPS fulfill this criteria?

More about GIS ► Has the ability to attach a variety of qualities and characteristics to geographical areas ► Qualities can be physical parameters (ie. Elevation and temperature), vegetation, ownership of land, zoning, etc. ► Qualities may be attached to points, but often are assigned to more complex features such as lines or areas

► Visualize data stored as theme layers with each layer linked to a common georeferencing system ► Layers may represent different attributes for particular purposes:  Market research ► Layers  postal codes, reports on demographics, purchasing habits, etc.  Firefighters ► Layers  connections of a water supply pipe network (critical to know which valves to close in order to increase water pressure)  State and local governments ► Layers  property lines, properties bordering a road if owners are affected by roadwork. Can you think of any other applications where the several layers in a GIS would be important? Can you think of any other applications where the several layers in a GIS would be important?

► GIS can link information from widely scattered sources ► Data can be easily represented in several different ways (graphical, tabular, etc.) ► Correlations can be made i.e.. It is possible to relate quality of groundwater at a site with the health of inhabitants, predict vegetation growth with respect to climate change, compare development proposals with restrictions of land use Where may this information be helpful? Do you know of any examples of GISs and how they benefit us?

Data Integration ► GISs have the capability of obtaining data from a variety of sources, including but not only maps, images from satellites, videofilm taken from aircraft, statistical data, photographs, data from computer-assisted design (CAD) systems and several other media ► As GISs advance their definition changes, and becomes more challenging to convey; for now we can consider GIS to be in the process of becoming a typical data integration machine ► Storage capacity of these systems is minuet in comparison with the complexity of the entire Earth

Storage ► 100,000 words can be digitally stored in approximately 1 million bytes (1byte=8bits) ► Information from a topographic map may take 100 megabytes (1megabyte = just over 1million bytes) to digitally capture ► One scene from a satellite can take over 300 megabytes, the equivalent space needed to store 300 books What is the relevance of this? What does it mean?

► On a map symbols are used to signify attributes such as roads and power lines, in a geographical database a road or power line would be represented with a series of points connected with straight lines  This allows the database to save space and implement the symbolization when the map is displayed

► Databases are vital in GISs because they allow the storing of geographical data in a structured manner ► Some GISs are imposing more structure by implementing database management systems (DBMS) to store part or all of the data in a largely independent subsystem under the GIS How does a DBMS help a GIS?

database vs. traditional filing cabinets ► Database  Stores and maintains data in one place  Stores in a uniform, structured, and controlled manner  Ensures that data are accessible to many users at once, each of whom has the same understanding of the database’s contents  Easily updated with new data ► Paper in filing cabinets  Data often stored in ways that are understandable to one person only  Data easily corrupted by use, or edited in ways that are meaningful only to the editor  Inaccessible to anyone other than the creator of the system  Data stored in formats and at scales that are so diverse that they cannot be compared or collated  Difficult to update data

GIS diversity ► The diversity of GIS has caused various definitions, typically users contrive working definitions suited to their own specific uses ► Views of GIS include  A data processing system designed for map production or visualization  A data analysis system for examining conflicts over plans or optimizing the design of transport systems  An information system for responding to queries about land ownership or soil type  A management system to support the operations of a utility company, helping it to maintain its distribution network of pipes or cables  A planning system to aid the design of road systems, excavations, or forest harvest operations  An electronic navigation system for use in land or sea transport

Definition ? ► Can we come up with one definition? ► GIS is now accepted internationally as an umbrella term for all digital systems designed to process geographical data.

Disciplines, applications, types of data and end users encompassed by GIS ► Disciplines: computer sciences, cartography, photogrammetry, surveying, remote sensing, geography, hydrography, statistics, information sciences, planning ► Applications: operation and maintenance of networks and other facilities, management of natural resources, real estate management, road planning, map production ► Data: digital maps, digital imaging of scanned maps and photos, satellite data, ground truth data, video images, tabular data, text data ► Users: water supply and sewage engineers, planners, biologists and cartographers, surveyors

► CAD  computer assisted design. Image processing system designed to perform a wide range of operations on images. ► As images become a more important part of GIS the distinction between image processing and GIS is becoming increasingly blurred ► Key terms for distinction:  GIS  analysis  process  CAD  extraction  design

► “Forest fires ravaging southern California, foot- and-mouth disease devastating the British livestock industry, the recent outbreak of severe acute respiratory syndrome (SARS)—all of these disasters have at least one thing in common: the role played by geospatial analysts, mining satellite images for information to help authorities make crucial decisions.”  It is for reasons like this that geotechnology is one of the three most important emerging and evolving fields, along with nanotechnology and biotechnology.

Questions/comments?