GIS Midterm-the ultimate lock in 🔥🔥🔥

It is estimated that _____ of the data that we collect every day is geographic.

80%

maps

Geographic data is unique, which can only be presented with______ which have been used for thousands of years.

GIS has been around for about _____ years, but only recently the digital revolution has

created the ability for the general public to use GIS

60

Why can the general public use GIS now?

◼ Computer hardware and technology are cheaper and more available;

◼ GIS software tools are becoming more powerful and easier to use;

◼ Geographic data collected in both the public and private domains are becoming more available;

◼ GIS industry and user communities have grown rapidly to impact almost all private and public sectors

A GIS is a computer system for:

Capturing, Storing, Querying, Analyzing, Displaying of spatial (geographic) data.

Geospatial data describes both the _____ and ______ of spatial features

locations;characteristics

Examples of GIS usage

Public safety, commercial/business, coastal management, healthcare

It is estimated that 80%-90% of the total cost of a GIS project goes to _______

data collection and management.

What component of GIS is this: Data capture technologies, e.g., global positioning system (GPS), aerial photography, satellite remote sensing, and census survey; Data management software, e.g., database systems

technology

What component of GIS is this: GIS experts, domains experts (e.g., business managers), and the general public.

People/Users

Information systems are

computer systems to help people find information from data. They are technologies (including both hardware and software) that assist users in creating, maintaining, storing, and retrieving the data that they need.

Geographic Information Systems (GIS) specializes in helping users transform ______ into ______

geographic data; geographic information.

What is information?

the data that has been selected or transformed to inform a particular decision.

GIS is______ to ArcGIS Pro

not equal

created one of the world's first maps, which was circular in form and showed known lands of the world grouped around the Aegean sea at the center. This was all surrounded by the ocean

Anaximander

The first GIS

The Canada Geographic Information System (CGIS), was conceptualized in the 1960s and became operational in 1971. It was designed to manage land and resource data for the federal government of Canada

In 1982, Environment Systems Research Institute (ESRI) released

ArcInfo, which is one of the first commercial GIS software packages.

Since fundamental issues related to data structures and representations were resolved in the 1980s, the focus of GIS development shifted to technologies for:

data collection, quality, standards, database organization, spatial analysis, and friendly user interfaces

The growth of computer technology in the ____ dramatically accelerated the development of GIS.

1990s

initiative by the U.S. government (1994, 1998) to provide all U.S. citizens access to information that affect their lives.

National Information Infrastructure

Factors that Helped GIS Evolve

Advancement of Computing Technology, Development of Software, Availability of Geographic Data, Need for GIS, Research, Education, & Training, Communication Paths

In order to do Gis you need a _____ for everything and the characteristics associated with it

location

A location on the earth

(xyz) we need multiple dimensions. (we need a reference)

The earths surface is not regular, why?

mountains, valleys, rivers, and oceans

a reference surface (or model) of earth that is used for plotting locations of anywhere on earth

Datum

A ______ represents the size and shape of the Earth by defining the position and shape of the Geoid or Ellipsoid relative to the center of the earth

datum

Mean sea level (MSL) approach

Imagine that the earths surface is all covered by water. In other words, we let the oceans flow freely under the continents. Thus we have a single undisputed global sea level covering the entire Earth, which is shaped only by gravity.

The mean sea level surface creates and approximation of the earths surface, which is called the

Geoid

Geoid

The colors in an image of a GEOID represent the deviations in heights (-100 m to +100m) from an ideal geoid. The blue colors represent low values and the reds/yellows represent high values.

-the shape of the geoid is not regular (its ugly)

Elevation

the vertical distance to the geoid surface

Since the Geoid surface is still too complex to mathematically describe, an ______ is used to approximate the geoid surface

ellipsoid

An ellipsoid is

formed by rotating an ellipse about its minor axis (corresponding to the axis of the earth's rotation)

In GIS ellipsoids are more commonly used than Geoids

because they are defined globally-mathematically simple. Geoids are defined by geographically local conditions rather than a single transformation- computationally demanding.

The earth is not a perfect sphere, why?

The distance from the 2 poles is shorter than the distance around the equator (oblate spheroid). Earth's ellipsoid is actually only about 1/300 off from the spheroid.

At every point the Geoid surface is perpendicular to the

local plumb line

Vertical Datum

a level surface to which heights (i.e., elevation) are referred

What kind of Datum is a Geoid?

Vertical

A vertical position is the ______ of a point relative to a vertical datum.

elevation

Horizontal (or Geodetic) Datum

a reference for horizontal position (e.g., latitude/longitude or coordinates)

What kind of datum is an ellipsoid

Horizontal