1. What is GIS ?
Definitions
Daniel Demonceau
08 / 21 / 2014
2. “A Geographic Information System (GIS) is a set of
tools to collect, manage, use, share and interpret
spatial information, to understand relationships,
patterns, and trends”
Daniel Demonceau, themagiscian.com
3. Elements of definition
Tools to perform the collect, manage, use, share and interpret spatial
information, can be:
∙ The same to perform all the operation
∙ Different for each task
∙ Materialized – eg: computers (hard- and software), gps
∙ Dematerialized (often NOT considered: GIS DO NOT always involve software
and hardware…) – eg: a paper map, a mindmap
GIS implies people and methods for running the whole system
… let’s dissect the tasks in the following slides
4. collect
Geographical data
∙ Latitudes, Longitudes, Altitude
∙ X, Y, h
∙ Postal Addresses
∙ Devices: GPS device, Total station, digitizing a map from a reference, People’s
experience, mental map, etc.
Attribute (data linked to geographic’s)
∙ Type of data: tree, road border, a position, etc.
∙ Details of the data: height, width, age, etc.
∙ Metadata: contact information, date, etc.
5. manage
Store
∙ Hard drive, flash disk, network drive, database, file based, the human brain!,
paper map in a folder on a shelf, sticky note (relative data), tabular data (both
numeric or paper), etc.
∙ Set up a coherent data structure
∙ Retrieve the data: index data, add metadata, index the folders on the shelf,
ask a colleague who disposes data, etc.
Enhance the added-value of the data
∙ Add/Update/Remove data (geometry and attribute)
∙ Validate data quality (precision, accuracy, completion, etc.)
∙ Change storage type (from file-based to database)
6. use
∙ Open data in a viewer software, unwind paper maps
∙ Measure distances, surfaces, calculate new coordinates, etc.
∙ Perform Analysis: points dispersion analysis, concentration of
phenomena, buffers, clip the data to keep a subpart, attribute and
spatial join, make a Demographic Analysis, a Define Risky Zones in
Case Of A Nuclear Accident Analysis, etc.
∙ See the results of the analysis
7. share
Share knowledge
∙ Provide the url to a Webmap via email, a website, social network
∙ Give the network location of data
∙ Give a paper map to somebody, or indicate where it is
∙ Show your friends on a paper map where you were on vacation
∙ Give a stranger in the street the direction to the place he wants/needs to go
∙ The GPS telling you the way to follow to reach your destination
8. interpret data
Draw your conclusions
∙ Define risky zones after a Landslide Risk Analysis
∙ Forecast the way a storm could follow based on past information
∙ Decide whether or not to trust the instructions given by the GPS voice while
driving a car (if the voice indicates you to go in a one-way street, a closed
street, etc)
For the same data and the same outputs, interpretation may differ
depending on people!
∙ The results of a Disease Propagation Analysis can drive ones to shout for RED
ALERT DANGER while for others the dissemination is negligible
∙ A sporty person may find that walking 3 km to see a church in town is not a
big deal while others would take the bus/tram/underground instead
9. some examples of GISs – example 1
Locate new stores
∙ Collect: location of existing stores, catchment area info (population, customer
behavior, road network)
∙ Manage: database–stored data (from an ERP), geospatial database/file, check level
of quality, interoperability
∙ Use: locate stores on a map, calculate isochrone for cathment area, combine with
customer behavior for attraction potential analysis, outline the « holes » on your
map which indicates potential sites for your new stores
∙ Share: show/present your results to your manager
∙ Interpret: the « store-desert » will probably be retained for new site
10. some examples of GISs – example 2
A surveyor measuring a site
∙ Collect: Total Station, GPS
∙ Manage: database/file based after import from device, index data,
check quality
∙ Use: create the blueprint of the future construction
∙ Share: send the map to the foreman, architect (CAD file, paper map)
∙ Interpret: the indications given on the map are needed for workers,
masons, etc.
11. some examples of GISs – example 3
In the street, a stranger asks you how to go by foot to a museum
∙ Collect: your mental map built over the years
∙ Manage: data stored in your brain and continuously updated as « things
change in town » (streets are temporary closed as works are done, streets
become one-way, etc.)
∙ Use: query your mental map to retrieve the way to the museum
∙ Share: tell the direction to the museum
∙ Interpret: the stranger imagine that it can be far away and is considering
going there by bus (and so, will ask you the bus lines)
12. some examples of GISs – example 4
Captains of boats trading between Europe and Asia did make use of
complete GIS!
∙ Collect: paper maps for navigation done by great explorers (Henry the
Navigator, Bartolomeu Dias, Vasco da Gama, etc.). Devices: sextant, surveying
tool, paper, pen
∙ Manage: paper maps used onboard, quality of maps checks, multi-scale maps
∙ Use: while onboard, navigation directions and distances can be retrieved
∙ Share: information shared among the managing crew, rowers, sailor
∙ Interpret: before the journey: estimation of food to take onboard for the long
trip, crew size, how much merchandise can be taken back. During the journey:
adapt the route when storm, need to accost in emergency
13. misdefinitions
Several definitions found on internet do NOT
enter in my personal definition of GIS
See the definition I DO NOT agree with
(The sources of the following definitions are not displayed to avoid blame)
14. definition 1
“A geographic information system (GIS) is a computer system designed
to capture, store, manipulate, analyse, manage, and present all types of
geographical data.”
Why I DON’T agree
It is not necessary a computer system!
∙ The 5 mains functions of GIS can be executed without computers! Software and
hardware are tools that can be used (they are mainly used now, that’s true)
∙ Remember that GISs existed far before the invention of computers
∙ This definition should include the ability to Share
15. GIS exists since mankind locate « things » in space
∙ Cavemen had their mental maps and did know where to go to hunt wild boars
∙ Bees as well have their GIS! They collect data about food location, interpret
them and tell the other bees where to go there! See HERE how they share this
information with their Waggle Dance
∙ What about the blueprint for the construction of the pyramids? Navigation
maps drawn by Magellan?
http://www.ancient-wisdom.co.uk/ http://en.wikipedia.org/wiki/Nautical_chart
16. definition 2
“GIS is a system of hardware and software used for storage, retrieval,
mapping, and analysis of geographic data.”
Why I DON’T agree
GIS is NOT a system of hardware and software for the same reasons as for
Definition 1
This definition does not take into account COLLECTING data, MANAGING, and
SHARING
17. definition 3
“A GIS is a software for organizing and presenting georeferenced
alphanumeric data. […] ”
HELL NO!!
A software, if present, is only a part of a GIS!
18. definition 4
“GIS: A computer application used to store, view, and analyze
geographical information, especially maps.”
Why I DON’T agree
An application (=software) : NO!
19. definition 5 – collection of misdefinitions
“In the strictest sense, a GIS is a computer system […]”
“A geographic information system (GIS) is a computer-based tool […]”
“GIS is an integrated system of computer hardware, software, and
trained personnel […]”
Internet apparently likes the way that GIS automatically involves
computers …
20. good definitions
Some definitions found in internet DOES
(partially) enter in my personal definition of GIS
See the definition I DO agree with
21. definition 1
“GIS is a general term that refers to any scientific effort integrate data to
help researchers visualize, analyze, and explore geographically referenced
information.”
Source: http://gps.about.com/
What I DO agree on
∙ ‘any scientific effort’ is a general term that does not take part in a particular tool
∙ Focus is put on the final purpose of GIS
∙ It has Data as inputs and Information as output
What I DO partially agree on
∙ The purpose of GIS is too narrowed with ‘help researchers’. The public is much more
broader than that!
∙ It only focuses on the use of GIS and not on data collection, manage and share
22. definition 2
“A geographic information system is a special case of information systems where the
database consists of observations on spatially distributed features, activities or events,
which are definable in space as points, lines, or areas. A geographic information system
manipulates data about these points, lines, and areas to retrieve data for ad hoc queries
and analyses.”
Source: Kenneth Dueker, Portland State University, 1979
What I DO agree on
∙ GIS is an IS
∙ This definition does not take part in a mean for managing in the general sense spatial data
∙ It also talks about ‘event’ and not only tangible things
Enhancement to bring to this definition
∙ Add the notion of capturing data, and sharing
What I DO NOT agree on
∙ The definition is focused on vector data. But data can include Raster Data, relative data (address-based),
non-geographic data which can be linked to geographic data.
23. definition 3
“Short for Geographic Information Systems, tools used to gather, transform, manipulate, analyze,
and produce information related to the surface of the Earth. This data may exist as maps, 3D
virtual models, tables, and/or lists.
GISs can be as complex as whole systems that use dedicated databases and workstations hooked up
to a network, or as simple as "off-the-shelf" desktop software.”
Source: http://www.webopedia.com/
What I DO agree on
∙ ‘Tools’ is use in a general way
∙ ‘information related to the surface of the Earth’ is a good way to describe the output of GIS (a best way would
be to include “everything localisable on Earth” (eg: geological layers, underground phenomena)
∙ Focus is on level of complexity
Enhancement to bring to this definition
∙ The is no notion of sharing information
What I DO NOT agree on
∙ There is no word about the purpose of the GIS
24. definition 4
“A geographic information system is a complex arrangement of associated
or connected things or objects, whose purpose is to communicate knowledge
about features on the surface of the earth. We can expand the definition of
this to include features above and below the surface of the earth.”
Source: http://www.washington.edu/
What I DO agree on
∙ The output information includes EVERYTHING on the surface and below
∙ Does not take part in a particular tool or manner the GIS is made of
Enhancement to bring to this definition
∙ Features are not the only output of GIS (there are maps, satellite data, etc.)
What I DO NOT like
∙ Focused on: ‘Communicate knowledge’, and not on what the GIS do before it (eg:
capturing data, managing, using)
∙ No word about the purpose of GIS except “Communicating knowledge”
25. definition 5
“A geographic information system (GIS) lets us visualize, question, analyze,
and interpret data to understand relationships, patterns, and trends.”
Source: http://www.esri.com/
What I DO agree on
∙ Does not focus on computer-based tools
∙ Includes the purpose of GIS
Enhancement to bring to this definition
∙ Add the GIS capabilities to collect, manage and share data
What I DO NOT like
∙ The definition is too large and should contain some elements linked to ‘Geography’
(‘Data’ should be changed to ‘Geographical Data’)
∙ The definition rather looks like to be the definition of the word ‘database’
26. conclusion
∙ Have a broader definition of what a GIS is instead of reducing it to
hardware and software
∙ Don’t forget the people running the whole system!
