GIS Education Center
1400 Evans Avenue
San Francisco, Ca 94124
Latitude: -122° 23' 6"
Longitude: 37° 44' 27"
| GIS FAQ's |
|
|
|
|
The following sections are designed to provide a brief overview of Geographic Information Systems (GIS) technology. Since GIS is a very broad and dynamic field of study, we hope that this information provides you with the basics, to help you get oriented. If you plan on taking a workshop please visit our GISEC student FAQ's page.
» Why is location information important? » What is GIS? » What does GIS do? » What fields use GIS? » How does GIS help us make better decisions? » What is GPS? » Why is GPS is useful? » What is Remote Sensing? » How is Remote Sensing used?
» Are there GIS jobs and is the industry growing? » Do I need a GIS Certificate and/or pass an exam to apply for GIS positions? » What type of skills/education do I need? » What websites have GIS job postings?
» Who is ESRI? » What is ArcGIS?
» What is the difference between Google Earth and Google Maps? » What is Safe FME?
♦ Why is location information important? Maps have been used since the earliest humans. Cave drawings depicted the location of seasonal animal migrations, water, and other significant features. Today, you can jump on Internet and find the nearest steak houses or pubs in your neighborhood. After thousands of years apart the concept of maps is apparent – they tell a story and help us make better decisions
The location of food, water, resources, habitats, and even people are all subject to dynamic natural and man-made processes. Understanding these processes helps us make better decisions when problems or opportunities arise.
The best method for humans to manage, analyze, and disseminate location information is with a GIS.
♦ What is GIS? GIS (Geographic Information Systems) is a combination of hardware (e.g. GPS units and computer workstations) and software (e.g. ESRI's ArcGIS 9.3.1) designed to capture, store, manage, display, analyze, and publish spatial information (information about locations or features on the Earth). Geographic information can simply be an address, latitude/longitude coordinates, or even a description about a location. Below are two examples of how spatial information might be listed:
♦ What can GIS do? The first (of five) powerful benefits of GIS is its ability to represent your spatial information as a graphic (typically as points, lines, and/or polygons) on your monitor that is correctly positioned on the earth's surface.
♦ That's great, but what else can GIS do? Glad you asked. First, because a GIS is database-driven, it provides the benefits of: • Storing vast amounts of data (gigabytes and even terabytes) • Serving as a central repository for data which reduces redundancy • Establish rules for data input to ensures data integrity (only certain values can be entered) In addition... • Dynamically update information: changes in your GIS are automatically reflected on your map • Change symbols and labels quickly: modify the look, color, or size of features and labels • Add layers of data: add many layers of information (e.g. roads, neighborhoods, schools etc.) • Query data: use expressions to derive results, such as "what neighborhood has the highest level of crime?" • Apply simple and complex analysis: analyze and produce queries and models that yield answers to questions, such as "what is the solar capacity for rooftops in San Francisco?" • Disseminate spatial data easily: share your maps and data over the web • Publish electronic or hard copy maps quickly: produce quality and professional looking maps
Lastly... The location of real-world geographic features (buildings, streams, streets, etc.) is a key component of almost any environmental or social analysis - and GIS is the only technology that allows us to perform spatial (location-based) analysis. For example:
Ever wonder why retailers ask you for your ZIP code? It's because they use this information in a GIS to analyze where and who their customers are (profiling) as well as to make sure you get their Spring catalog.
What about the impact of a new shopping center or industrial plant in your area? GIS is used to assess air pollution from traffic or plant burn-off, to model habitat destruction and predict effects on human health.
How about the next earthquake or hurricane? GIS is a critical component in understanding and preparing for natural and man-made disasters. It can answer questions involving the location of emergency shelters or the likely populations that might be affected by the accidental release of a chemical plume
You can think of GIS as designing "smart maps" that display correct distances, locations, and enable spatial analysis. In a nutshell, a GIS links information in a database (like a spreadsheet) with graphics on a map. Once you recognize the power that this linkage yields, you can see some of the many advantages of a GIS.
♦ What fields/disciplines use GIS? GIS is used across a wide variety of disciplines, this list is a good start:
Archaeology: GIS is used to locate hidden settlements under vegetation, map artifact locations, and visualize change over time in an area Biology: GIS is used to map species, determine suitable habitat, understand the effects of human disturbances Business: GIS is used to find the best location for a business, marketing analysis, and customer locations Environmental Resource Management: GIS can assist in identifying suitable habitats or areas to protect. Health: GIS is used to visualize the spread of disease or locate gaps in the provision of health services in a community. Sociology: GIS is used to understand where people live, access to services, and analysis of community dynamics Transportation: GIS is used extensively to manage transportation facilities and to plan routes for future roads and rail services Urban Planning: GIS is used to evaluate the impacts of growth on a community and to plan its future use of land Utilities: GIS is used to plan the route of utility expansions or to evaluate efficiencies in the distribution of service to customers
If your interested in adding spatial analysis to your project and want to understand more about how GIS works and how it can help you, then continue with the rest of this GIS FAQ page.
As mentioned above, the first powerful benefit of a GIS is to represent your spatial data correctly as a graphic. The second powerful benefit has to do with the information about a location. All locations, or features, can or will contain additional characteristic information like the type of feature or other descriptive qualities (or quantities), these are called "attributes" in a GIS. Examples include:
(Number of families by neighborhood and attributes for West of Twin Peaks neighborhood. Source: SFGIS - Planning Neighborhoods)
In a GIS the location and attribute information are linked. This linking is the second powerful benefit of a GIS as it allows data to be managed, analyzed, and viewed in a graphic or tabular/spreadsheet format.
The linking of graphics and records is the key component in GIS as it established a bi-directional relationship between records and graphics. This means you can select or query records in the table to highlight the corresponding features in the map. Or select features in the map to highlight their records and get their attribute information. The select functions in a GIS are critical when it comes to performing spatial analysis and other GIS functions.
This brings us to our third powerful benefit of GIS - the ability to query using attributes and/or location. Because GIS is database driven it provides the typical database query functionality (greater than, like, range, etc.) or equations you'd find in Excel (sum, average, mean, etc.). However, GIS provides a unique query function that separates GIS from normal database applications - query based on location.
An example demonstrating the third powerful benefit: In this scenario, your at Northern California Regional Response Center and there's a chemical release from a plant. You'll need to know what fire departments can respond, what hospitals can handle a large number of patients, and identify the high areas of elderly and young.
First you'd select based on attributes: • Select FROM "Fire Department" That are RESPOND TYPE "Chemical"; • Select FROM "Hospitals" that are TYPE "Emergency Room" AND have greater than "1000 Beds"; • Select FROM "Census tracts" that are TYPE "65 and Older" OR "5 and Under" that have greater than "1000";
Now, highlighted on your map are the locations of fire departments who can respond, hospitals who can handle a large capacity of patients, and those census tracts where there's a large number of elderly and young for your region. This is a great start but your region is Northern California and the incident is in Monterey (sorry Monterey) which means all the services in upper Northern California are too far away to assist. What you need is a query to select those services within 10 miles of the incident - from the already selected services. This is something only GIS can do.
Select based on location: Select FROM the SELECTED "Fire Departments", "Hospitals", and "Census tracts" that are within a distance of "10 miles" from the incident.
Result: Now, your map has identified the appropriate services. You can then begin notifying hospitals and local authorities about the problem and set in motion the Standard Operating Procedures for such an incident.
This example demonstrates the powerful and unique capabilities of GIS. And it also shed light on why GIS helps us make better decisions.
♦ How does GIS help us make better decisions? GIS allow students, researchers, and professionals to incorporate a spatial quality to their projects. Consider this example: a spreadsheet (like Excel files) or a relational databases (such as a Microsoft Access file) might list a number of customer addresses. While this information is valuable, by itself it is hard to discern patterns, locational relationships and other geographic qualities (such as "how many of these addresses are in my market study area?"). However, in a GIS, the customer locations can be linked to points on a map. After doing so, the adage "a picture is worth a thousand words" really becomes true! Now that the customers are shown on a map, locational relationships are revealed and more in-depth analysis can take place. In short, then, a GIS links information about where things are with information about what things are like.
(Coffee shops in San Francisco and neighborhoods. Source: Coffee shops by Rick Kos and Mono Simeone; SFGIS - Planning Neighborhoods)
Another example: children and the elderly are more susceptible to harmful air pollutants. As a GIS user, you would most likely want to produce a map composed of individual map layers related to this topic. Such map layers might include locations of reported respiratory problems, neighborhoods, parks, schools, roads, and Census tracts.
(Source: SFGIS - Planning Neighborhoods, Public Schools, Major Roads, Parks)
Additional information and analysis of air pollutant, traffic data, and weather patterns could provide further insight into the spatial patterns and relationships. These examples demonstrates the fourth powerful benefit of GIS - the ability understand and/or model our environment by analyzing spatial phenomenon.
The fifth powerful benefit of a GIS is the ability to produce and publish high-quality maps. GIS roots stem from spatial analysis - not making pretty maps. In the past, design applications like Illustrator or Freehand were used to publish maps. Recently, GIS has developed robust cartographic capabilities and tools to reduce the need for other applications. To learn more about cartographic design in GIS sign up for our Information Design with Maps workshop.
If you wish to learn more about GIS, please sign up for our free, introductory GIS Theory & Practice workshop. Or, if you are interested in taking an introductory GIS workshop, please consider our GIS Quick Start workshop page. For more information about GIS, an excellent overview is provided at Environmental System Research Institute's (ESRI) web site: ESRI Guide to GIS.
♦ What is GPS? GPS (Global Positioning Systems) is a method of recording one's position on the Earth. By now you have probably seen or played with a GPS device, either in a car or on your phone. These devices (or receivers) are calculating your position by communicating with several satellites above the Earth's atmosphere. When a GPS device receives enough information from at least 3 satellites, it can begin to determine (through a process known as "triangulation") your position on the Earth.
♦ Why is GPS useful? GPS helps us determine where we are and will give us directions to the nearest, say...doughnut shop. However, GPS devices are becoming more powerful over time by delivering higher accuracies and allowing users to input more information such as a photo of the user's location or a particular asset (fire hydrant, hiking trail, etc.) being captured. These are a few examples of how GPS is used:
Biology: GPS can help to determine range of habitat, hunting grounds, or migration patterns Asset Management: Large organizations, like UPS, will use GPS to track parcels in shipment. People: As scary as it sounds, GPS has been used track people, knowingly and unknowingly. Some cities have starting using GPS to trace where sex-offenders reside and move.
To learn more about GPS and how to use GPS units sign up for our Data Acquisition and GPS workshop.
♦ What is Remote Sensing (RS)? You are probably most familiar with remotely sensed data from Google Earth or Google Maps. All of the aerial imagery you view in these applications was captured using remote sensing technology (probably from an aircraft or satellite), processed by imagery technicians, then disseminated in products for you to explore. Technically, RS is the detection and measurement of wavelenghts reflected or emitted by objects. So, in a broader sense RS is the acquisition and interpretation of data from a device (camera, radar, or other sensors) housed on an aircraft, ship, or satellite.
Sensors capture data by: • Recording the amount of light reflected from objects (photography) > Compare aerial images over time • Recording the amount of energy emitted by objects (thermal) > Calculate water or terrestrial temperatures • Recording the distance to objects (sonar or LIDAR) > Derive elevation for terrain analysis
Collected data is then processed and turned into an image for analysis and/or map generation.
♦ Why do we use Remote Sensing? Remote sensing allows us to record information about inaccessible or dangerous areas. However, more importantly a vast amount of analysis can be performed on RS data. Examples of analysis using Remote Sensing data include: • Archaeology: locate historic structures/settlements under vegetation • Biology: calculate habitat destruction, deforestation, locate diseased vegetation • Environmental Resources: Calculate and locate solar and wind energy capture • Geology: locate minerals, calculate soil loss • Hydrography: watershed analysis, flooding • Urban Planner: calculate urban sprawl
If you want to know more about GPS and Remote Sensing data sign up for our Data Acquisition and GPS workshop.
We hope this brief explanation of GIS technologies has been helpful and we invite you to take a look at the map gallery to better understand how GIS is being used by people all over the world.
♦ Are there GIS jobs and is the industry growing? Yes. According the Department of Labor, geospatial technologies are one of three fastest growing industries in the U.S. In addition, the Bureau of Labor Statistics, occupation outlook handbook 08-09, rates that geospatial jobs are expected to grow much faster than the average for all occupations through the year 2016.
♦ Do I need a GIS Certificate or must I pass an exam to apply for a GIS position? No. There is no standard GIS certification required for GIS positions. Also, there is no state-licensed GIS exam to pass, such as for engineers (FE/PE) or land surveyors (FS). Therefore, employers typically value project and software experience in an applicant's resume.
♦ What type of skills/education do I need? Today, employers typically value work or project experience, supplemented by a solid grounding in geographic theories, concepts and spatial relationships. To an employer, a candidate who already possesses these skills is very valuable, since training time is likely to be minimized. This experience also should demonstrate that a candidate can solve problems and produce deliverables such as project maps or summaries of statistical data. Gaining hands-on experience and creating a portfolio of projects will, in most cases, increase your chances of obtaining a GIS related position.
Typically, people follow two paths when learning GIS:
1) Goal: become a GIS Technician, Analyst, or Project Manager. In this scenario, a student at our GIS Education Center would typically enroll in our two GIS Quick Start workshops, our Data Acquisition workshop and our Information Design with Maps workshop in order to gain a well-rounded set of skills with GIS.
2) Goal: develop GIS as a skill to augment existing skill sets; for example, an urban planner may wish to add GIS to her "toolbox" of skills used to analyze complex urban environments. In this scenario, a student at our GIS Education Center would typically enroll in our two GIS Quick Start workshops, followed by some of our industry-specific workshops such as GIS and the Urban Environment.
♦ What websites post GIS jobs?
• Directions Magazine Jobs Listing
♦ Who is ESRI? The Environmental Systems Research Institute (ESRI, pronounced ez-ree), based in Redlands, California, is the leading desktop GIS software provider in the United States. ESRI products are widely used in government agencies, private firms, and non-profit organizations. In addition, ESRI hosts the largest GIS conference in the world, drawing over 10,000 participants to San Diego each year. The GIS Education Center is a member of the ESRI Academic Site-wide License program which makes just about all of ESRI's applications (desktop, enterprise and web-based) available to our students.
♦ What is ArcGIS? ArcGIS Desktop is ESRI's suite of desktop GIS applications. The current version is ArcGIS 9.3.1 which is installed in all of our learning labs. ArcGIS provides the tools necessary for a GIS student or professional to design, implement, and maintain a GIS for their particular projects. ArcGIS is comprised of three primary applications: ArcMap (where you design and layout your map), ArcCatalog (for managing and organizing GIS data) and ArcToolbox (containing tools that accomplish specific tasks, such as converting data from one format to another). Additional extensions to ArcGIS are available for specific purposes, including:
Spatial Analyst: this application provides tools for analyzing raster data (e.g. aerial photos, satellite imagery) in order to study phenomena such as urban sprawl, the tracking of diseases, locating optimal sites for a new business, and locating and profiling customers.
Network Analyst: this application helps the GIS practitioner analyze network data sets such as transit routes, water and sewer lines, and electric utility networks. Typical studies that can be conducted with Network Analyst include finding the shortest route between locations, identifying the area that can be serviced from a particular location (such as the area that can be accessed in 5 minutes by walking from a transit station) and locating the closest facility to an incident (such as identifying the closet hospital to a vehicle accident).
3D Analyst: this application allows the GIS practitioner to visualize their two-dimensional geospatial data in three dimensions in order to better model real-world geographic phenomena. Typical uses of 3D Analyst including the analysis of sub-surface materials, identifying the slope of terrain, and modeling urban form (buildings, landforms, etc.)
Online mapping: ESRI provides a number of tools, such as ArcGIS Server, that allow GIS practitioners to author maps and publish them to the Web for use by others. For example, an organization can produce maps and tools at their office, then publish them to a web site for consumption by their clients or customers, allowing them access to simple tools for the querying and visualization of GIS data.
♦ What is the difference between ArcView, ArcEditor, ArcInfo and ArcGIS? This, admittedly, is one of the more confusing aspects of ESRI's product line since the prefix "Arc" precedes most of the company's products. Think of it this way: ArcGIS is a "suite" of GIS software, comprised of a number of applications that work seamlessly together (ArcMap, ArcCatalog, and ArcToolbox - described above) and distributed in three distinct license levels. ArcView is the basic license level of ArcGIS and is suitable for most GIS users. It contains dozens of tools for spatial analysis and is ready to use out of the box. For GIS practitioners requiring more analysis tools, ESRI offers the ArcEditor license level of ArcGIS which contains all of the functionality of ArcView, plus more. At the top of the hierarchy is ArcInfo which contains everything in ArcEditor but with the addition of sophisticated tools for truly scientific-level spatial analysis.
♦ Where can I find data for ArcGIS? Data is the "fuel" of a GIS and, fortunately, one can obtain vast amounts of free or low-cost data from Internet sources (e.g. the United States Census Bureau or www.geographynetwork.com) or from local and regional agencies (e.g. the Metropolitan Transportation Commission in Oakland, the City and County of San Francisco, etc.) In our workshops, you will access and use data sets from local agencies in order to gain as much exposure as possible to the data being used by today's geospatial professionals.
♦ What is the difference between Google Earth and Google Maps? Google Earth is a freely-downloadable, interactive virtual globe (3D) desktop application that allows you to explore the Earth's geography. Google Maps is an online mapping application (2D) viewable through any web browser. We tend to think of Google's mapping products as "cousins" to a GIS since they are primarily used for VIEWING geographic information, not ANALYZING it.
Google Earth's interactive features allow users to add content to the globe, create tours, and share this information with other users who have Google Earth. In addition, Google Earth provides content to enhance the virtual globe, such as aerial imagery and Wikipedia articles.
Google Maps is a web-based mapping site, viewable through any web browser, and offers a simple interface for tasks such as finding addresses and obtaining driving directions between locations. It also offers a search for businesses, landmarks, and other features, assisted by Google's web search engine.
Other free virtual globes that we recommend you download and explore are: NASA World Wind and ArcGIS Explorer 500.
♦ What is Safe FME? Safe FME is a toolset to quickly transform, translate, and integrate data. One common use of Safe FME is to convert data from one format to another, such as CAD to GIS. FME provides tools to convert over 200 data formats, and tools for coordinate system transformations.
|
|||||||||||||||||
