Introduction to GIS - facegis.com
Introduction to GIS

1. What is GIS?

GIS is the automated acquisition, management, analysis and display of spatial data.

A Geographical Information System (GIS) deals specifically with geographic (or spatial) information, rather than other types of data (such as financial or personnel). These are represented as different layers where each layer holds data about a particular type of feature. Each feature is linked to a geographic position.

The term "GIS" is perhaps a loose one (although first coined by pioneering Canadians) since:

    a. Non geographers prefer to use 'spatial' or 'land' instead of 'geographic'.
    b. Information can mean many different things.
    c. 'Systems' describes both the software and the discipline of GIS, which is often referred to as GIScience
    (some people incorrectly refer to a 'GIS system', which makes no sense as the S also stands for system)
Hence, other terms have been suggested (although GIS has now 'stuck'), such as:
    SIS / LIS:     Spatial (or Land) Information Systems. (often preferred by non-geographers)
    GIP: Geographic Information Processing 

GIS resulted from the need to OVERLAY different map layers: early cited example of the Irish Railway Atlas (1850)

    The term GIS was first used by the developers of the CGIS (C for Canadian), the world's first operational GIS in Ottawa, 1971. This project designed a computer system to input and manage the database for the Canada Land Inventory (CLI). Its leader, Roger Tomlinson  is widely regarded as the 'Father of GIS'. 

2. Cartography versus GIS

GIS grew from Cartography: there is a close inter-relationship between (digital) cartography and GIS, within Geomatics

At UNBC, this is reflected in the links between GEOG205 (Cartography and Geomatics) and GEOG300


Many standard GIS operations were previously conceived and executed on analogue maps (e.g. calculating slope from contours). Conversely, many users adopt GIS primarily to make maps, either standard mapping products or to illustrate the results of GIS analysis. Example: Manitoba Geological Survey gallery

The prime differences between a GIS and a mapping system are in their functional components:

A GIS contains these four components:

    a. Input                 b. Database                  c. Analysis                   d. Output
In contrast, a mapping (cartographic) system can be described in three components:
    i. Input                                ii. Map design                                   iii. Output

This difference is best shown in a software query that lists element attributes

CARTOGRAPHY
 GIS 
Feature type
Area (m2)
Boundary colour
Perimeter (m)
Pattern
Primary species
Fill colour
Secondary species 
Design level 
Average tree height

 ...in other words, a cartographic query gives information on design features (ii above), while a GIS query yields details or parameters about the features themselves, where the data are stored in a GIS database (B. above). We can't "ask" a cartographic map to display where forest cover is "spruce" and average tree height is 50 metres. However, we can ask a GIS the same question and it will display where the query is true.


3. GIS & Related Mapping technologies

GIS software must have these four components:

a. Means of data input
b. Database management system (DBMS)
c. Analysis capability
d. Graphics output


Related types of mapping software may have some but not all of these capabilities:

    CAD:   Computer Assisting Drawing, e.g. AutoCad, Microstation       a, d
    GDS:   Graphic Design System, e.g. CorelDraw, Illustrator                a, d *
    DBMS: Database Management System, e.g. Oracle, Sybase            a, b
    DIPS:   Digital Image Processing System, e.g. PCI, Erdas                a, b, c, d
    GPS:    Global Positioning Systems, e.g. OZIexplorer                       a, d

* GDS usually do not include 'Spatial geo-referencing' (see lecture 3)

Each of these may perform better than a GIS at their specialty, but only a GIS has all four components:
e.g. mapping software may be better for map production, databases for database management ..


4. Types of queries a GIS can Answer

a. Location

    WHAT exists here - what is at a particular location?
    Examples : "What is at 1 000,000N and 546,000E ?" Forest attributes or municipal ownership.

b. Condition

    WHERE are specific conditions -
    Examples : "Where does it rain 250 cm per year ?"  or  where are all houses owned by person x?

c. Trends

    WHAT HAS CHANGED (over time) -
    Examples : "How far has the river bank receded in the past 2 years ?"
    Areas harvested between then and now, houses increased in price by > 50%.

d. Patterns

    HOW are patterns related
    Examples : "How does proximity to salmon streams affect the number of bear attacks";
    Harvested watersheds and stream water quality, traffic accidents and road surfaces.

e. Modelling

    WHAT IF ..? -
    Examples : "What would happen to the view if we harvested 10 ha of trees from the valley "
    What if the climate warmed by 2 degrees? (effect on habitats) Prince George example

 

Source: http://www.gis.unbc.ca/courses/geog300/lectures/lect1/index.php