Do you have questions about geographic information systems (GIS)? Read the GIS FAQ for answers.

Do Center for Spatial Analysis (CSA) employees get to do any field work?
Some CSA employees do fieldwork; others do not do fieldwork. Much of the data collected or created for the Marine Resource Geographic Information System (MRGIS) requires careful "ground truthing" (sampling in the field) to make sure the data are accurate thematically and spatially. CSA is also involved in emergency response to oil spills, fish kills, and other disasters.

What is GIS?
GIS stands for Geographic Information System. GIS is a computer-based tool that provides users with the technology to reference complex spatial data to help understand and/or find solutions for a variety of questions or problems. GIS is widely used in business (e.g. real-estate offices, marketing firms), environmental research and management (e.g. state agencies, private research centers), urban planning (e.g. county tax appraisers, regional planning councils), and many other applications. The emergency 911 system is an example of a GIS.

According to Environmental Modeling with GIS, the use of GIS analysis has been developing and expanding since the 1960s. GIS works to take complex arrays of spatially explicit information from a variety of sources to provide accessible data for the purpose of solving issues in fields as diverse as environmental management, urban planning, and national defense:

A system of hardware, software, data, people, and organizations for collecting, storing, analyzing, and disseminating information about areas of the earth. The use of the term Geographic Information System dates back to the mid-1960s, where it seems to have originated in two quite different contexts. In Canada, it was devised to refer to the use of a mainframe computer and associated peripherals (notably a scanner) to manage the mapped information being collected for the Canada Land Inventory, and to process it to compute estimates of the area of land available for certain types of uses. Much of the proposed analysis was concerned with measuring areas simultaneously on two maps, to answer questions like "How much area is class 1 agricultural land and not currently used for agriculture?" The ability to overlay two or more maps for analysis (in this case a map of soil capability for agriculture with a map of land use) has always been a strong argument for GIS, because it is so cumbersome by hand.

Almost at the same time, researchers in the U.S. were struggling with the problems of accessing many different types of data required by the large-scale transportation models then in vogue, and conceived of a GIS as a system capable of extracting appropriate data from large stores, making them available for analysis, and presenting the results in map form. Such models combined information on population distributions with other spatially distributed information on places of employment and transportation routes, and required access to data in a variety of formats.

Almost 30 years later, these same arguments are still among the most frequently heard justifications for the use of GIS, particularly in environmental modeling and policy development. (Goodchild)

M. F. Goodchild et al., (eds.), Environmental Modeling with GIS, Oxford UP, New York, 1993.

What is Remote Sensing?
Remote Sensing is any method of sensing something from a distance. It is collecting information about an object or phenomenon without touching it. For example, photographs, X-Rays, and pictures taken from satellites or airplanes are all types of images that are sensed remotely. Typically, remote sensing and GIS go hand in hand. Remote Sensing provides the raw data, which are processed, interpreted, and then "fed" into GIS for analysis.

Remote Sensing is "the acquisition and measurement of data/information on some property(ies) of a phenomenon, object, or material by a recording device not in physical contact with the feature(s) under surveillance. Remote sensing techniques involve amassing knowledge pertinent to environments by measuring force fields, electromagnetic radiation, or acoustic energy employing cameras, lasers, radio frequency receivers, radar systems, sonar, thermal devices, seismographs, magnetometers, gravimeters, scintillometers, and other instruments" (NASA Web site).

"The Remote Sensing Tutorial," NASA Web site, n.d., <> (n.d.).

What is the difference between GIS data and maps?
A GIS stores and manipulates spatial information such as land use, housing density, or water bodies. Maps may portray several of these GIS datasets overlaid on top of one another. Maps will have a title, legend, scale bar, north-seeking arrow, and, usually, text describing the individual GIS datasets (source documentation). In addition, a map may have to meet certain cartographic requirements (map design elements) and map accuracy standards (such as the National Map Accuracy Standards). Maps are "static" representations usually plotted out on paper or Mylar® whereas GIS data are digital and can be continually updated and incorporated into many different types of maps.

Who creates all the data in the MRGIS?
In addition to creating data, FWRI obtains data from a number of federal and state agencies, such as the United States Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the Florida Water Management Districts, the Environmental Protection Agency (EPA), and many others. The CSA section at FWRI maintains and updates the MRGIS as needed and spends considerable time tracking down new datasets, which may be useful for studying Florida's coastal and marine resources.

FWC Facts:
The St. Johns River hosts the southernmost population of spawning American shad in North America.

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