Gluch Geog 212 Final - Spring '11

Geography 212 with Gluch at Brigham Young University

About this deck

By: Sharee Compton
Created: 2011-06-13
Size: 33 flashcards
Views: 9

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Components of a GIS

hardware, software, infrastructure, people, data

Freedom of Information Act

obtaining GIS data from the government

Nominal

Each item is named (Qualitative)

Ordinal

items are hierarchical, some are listed higher than others ex: 1st 2nd 3rd (Qualitative)

Interval

no fixed zero ex: temperature (Quantitative)

Ratio

zero means zero; number measuring something (Quantitative) ie. 5:100

Vector/raster data models

Vector= may be georelational or object based, may or may not involve topolgy and may include simple or composite features. Use X and Y coordinates to represent points.
They also include points lines and polygons
Raster = use cells in a grid to represent point features

Metadata

data about the data, such as who collected it, how, when, why, what methods were used.

Sources of spatial data

government, GIS clearinghouses, SGID (State Geographic Information Database)

Methods of data entry

scan existing maps, digitizing, image processing, GPS, surveying, geocoding

Sources of uncertainty/error

spatial and information, derived sources (maps, secondary data), measuring device (like a GPS unit), bias/subjectivity, sampling, spatial autocorrelation(like values close to each other), interpolation(estimation), incorrect overlay.

Histogram

a bar graph

Types of thematic maps: (2)

choropleth- pre- defined boundaries. This usually contains shading. An example would be a political map like the US States.

isarithmic- Data define boundaries; contour map. (ex: weather map 40’s 50’s)

Considerations in map design

Purpose-message, usage context; Audience- knowledge, public/private.

Projection (common types)

cylindrical- best case; conical- great for mapping mid-latitudes; azimuthal- good for mapping poles; simple case-one point of line tangency; secant- two points of line tangency.

Coordinate system (common types)

Location reference system for spatial features on earths surface. Defined by latitude and longitude. Exa: UTM - the northing values are measured continuously from zero at the Equator, in a northerly direction. State Plane- each zone has its own projection (LCC - long axix E-W) or Transverse Mercator.

Datum

a point of reference used to measure locations on the surface of the earth. It defines the origin and orientation of the lines of latitude and longitude.

Visual hierarchy

most important things should look most important. Helps to maintain clarity and avoid confusion. The most important elements should clearly stand out to the map user and not get lost in all the secondary elements.

Normalization

a process of decomposition, taking a table with all the attribute data and breaking it down into small tables while maintaining the necessary linkages between them. Normalization helps to avoid redundant data and assure that attribute data in separate tables can be maintained and updated separately.

Methods of attribute classification

Natural breaks- classes are based on natural groupings of data values. Class breaks are set where there is a jump in values, indicated by a large step between bars.
quantile- each class contains an equal number of features.
equal interval- the difference between the high and low values is the same for every class.

standard deviation-features are placed in classes based on how much their values vary from the mean

Decision support

Solving problems and using the decision method.
Decision Method: 1. Define the problem 2. define the Criteria 3. Identify the Data 4. Plan the analysis 5. Prepare the data 6. Execute the analysis and 7. Examine and present results (Chapt. 11 slide 4)
- Problem, Criteria, ID the Data, Plan, Prepare, Execute, and Results are the key words to memorize.

Suitability analysis

What area is good (or bad) for doing “x”

Location/Allocation analysis

A spatial analysis approach that matches the supply and demand by using sets of objectives and constraints

Service Area

the area that can be effectively covered by a certain service, such as a fire station. A service area can be used to show areas of a city covered by a fire station within a 5-minute response time.

Shortest path

find the path with the minimum cumulative impedance between nodes on a network. Shortest path can help a driver plan the shortest rout between home and work place.

DEM

Digital Elevation Model. Raster data that contains elevation information.

Model

A simplified representation of a phenomenon or a system.

Polygon overlay (common types) 1

Union-preserves all features from the inputs. The area extent of the output combines the area extents of both inputs

Polygon overlay (common types) 2

Intersect-preserves only those features that fall within the area extent common to the inputs.

Polygon overlay (common types) 3

Symmetrical Difference- preserves features that fall within the extent that is common to only one of the inputs (pg. 227) *I don’t know if we need this one, i dont remember ever talking about it in class.

Buffer

a Proximity tool that is used to create two distinct areas on your map: the area that is within a specified distance of selected features, and an area beyond that specified distance. (Area within the specified distance is the buffer zone). Ex: a 100m buffer around a major road will show an outline around the area within that 100m distance.

Network topology

chapter 17. Network applications require that a network is vector-based and topologically connected. A network is a system of linear features that has the appropriate attributes for the flow of objects. A network is typically topology-based: lines (arcs) meet at intersections (junctions or nodes), lines cannot have gaps, and lines have directions. (pg.373).

Boolean expression

A combination of a field, a value, and a logical operator, such as “class”=2, from which an evaluation of True or False is derived.

About this deck

By: Sharee Compton
Created: 2011-06-13
Size: 33 flashcards
Views: 9

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj