ENR 3700 Exam

Direction

"where's north"

What are coordinate systems?

A frame used to define the locations of geographical entities using some coordinate values (x,y)

Discrete data

Are distinct features that have definite boundaries and identities (Vector)

Geoid

As a very bumpy, irregular surface with equal gravity (the actual shape of the earth)

What are the two components of spatial data?

Attributes and location

ancillary information

Author, date (when map was made), location of map file(s), and supporting data, source data and projections, map maker, data sources, legal considerations

Continuous data

Has no define borders or distinctive values, instead, a transition from one value to another (raster)

What is the spatial information flow?

Collection --> GIS --> cartographic presentation (maps) also how we lie

Observational data

Observe subjects and measure variables of interest without assigning treatments to the subjects. That treatment that each subject receives is determined beyond the control of the investigator

primary data

first hand data gathered by researchers themselves

Global (map algebra)

one value for entire image is computed

Point of Origin

point where earth and ellipsoid align

Visualization of vector

points, lines, polygons

Examples of vector data

points, lines, polygons, Triangulated irregular networks

Mixed Pixel Problem

Some cells may encompass two or more features and only one may be marginally dominant and that is what is represented on the map

What are some problems with using coordinate systems?

There are 1000s of different systems each giving slightly different answers

How do we define a place on earth?

With coordinate systems or use the US Public Land Survey System

*Reclassification* Could we use this on the DEM file?

Yes We took the information we needed from the .zip file and further altered this data to show specific locations on our maps (same as NLCD)

*Reclassification* Could we have used this in the NCLD data from the lab?

Yes, by going to the NLCD website and renaming the colors that they associated with various land features both natural and man-made.

Very small scale

above 1: 250,000

Advantages of Vector Data

accurately represents true shape and size, representing non-continuous data, conserving disk space

examples of raster data

aerial imagery and digital elevation models

Color

affects interpretation

Relationship between data and information

collection of details about something that is vital for another process

Disadvantages of Vector Data

complex data structures, simulation may be difficult, spatial analysis can be difficult or impossible

Orientation

position of the ellipsoid

How do geographic and projected coordinate systems compare?

projected coordinate systems determine absolute location

Projected Coordinate System simply called

projection

Scale

representations of map figures to their ground equivalent

Four types of distortion

shape, area, distance, direction

Advantages of Raster Data

simple data structure, easy overlay, various kinds of spatial analysis, uniform size and shape

Local (map algebra)

single pixel calculation

Large scale maps cover ____ areas

small

Data source

source and data for both the geographic data and attribute data

Reclassification

strategic placement of an object, person, or idea under a new heading taking someones information and map algebra and making it useable for yourself.

Attributes

that describe phenomena, processes, and characteristics for feature or entities on earth

Location

that tells where the features and entities are on the earth or in our environment

What is map algebra?

the cell by cell combination of raster layers

Information

the organization of DATA such that it is valuable for analysis, evaluation, and decision making

Focal (map algebra)

use a neighborhood to change a single pixel

Zonal (map algebra)

uses map constraints to change pixel value

5 key strategies for interpreting maps

who is using the map, who is making the map, the purpose, the content, the scale

What does GIS stand for?

Geographic Information System

Best solution for the mixed pixel problem?

Winner take all

How is raster data stored?

.jif, .tif

How is vector data stored?

.shp, .shp.mxl (metadata), .dbf, .prj

Visual Balance

- The size of symbols - The pattern of the symbols - The color of the symbols - The visual hierarchy of the symbols and elements - the location of the elements with respect to each other and the visual center of the map

How is GIS used?

- Used to manage, analyze and present information - used to navigate - used to understand spatial phenomenon - used to explore the world near us - used to better manage the world around us

What are the three questions you need to answer before making a map?

-The people who may use the map (the audience) - The objective(s) of the map (the message) - The data that will be displayed in the map (the information available)

Small scale

1: 10,000 to 1: 250,000

Which is the larger scale map: 1:100,000 OR 1: 24,000

1: 24,000

Medium-scale

1:1,000 to 1: 10,000

Large scale

1:250 to 1:1,000

Projected Coordinate System

2D, projection, classification of projected coordinate system, planar

Geographic Coordinate System

3D, understand the shape and geometry of Earth, define the concept of datum, latitude and longitude

Datam definition

A mathematical model that defines and standardizes the shape of the earth including three elements

Ellipsoid

A model to approximate the shape of a geoid (earth) A sphere that is smushed down in the middle

Location Inset

A smaller more zoomed in section of the map (think of what we made during lab 4)

Common non-GIS ways to establish location

Come here, see you there, street, road, city etc.

What is the first principle of Krygiers 5 principles of map design?

Concept before compilation. You need a full concept of the map before you can make it (who, why)

Shape distortion

Conformal- shapes are distorted, depicted too small or too large On Earth: regular square On Map: distorted square (stretched, etc.)

Three elements of datum

Ellipsoid, Orientation, Point of Origin

Contrast

Emphasizes what information you want to be gleaned from the map

What is the fifth principle of Krygiers 5 principles of map design?

Engage the emotion to engage the understanding

Area distortion

Equal area size- preserves area, size on map is relative to size on earth On Earth: normal rectangle On Map: stretched rectangle

Distance/ scale

Equal distant- preserves true scale for all straight lines passing through a point On Earth: regular line On Map: Extended line

People associate colors of mapped features with ____, emotions and ______

Events/ socioeconomic status

Tobler's First Law of Geography

Everything is related in someway to everything else, but near things tend to be more related than distant things

What is the second principle of Krygiers 5 principles of map design?

Hierarchy with harmony the important things should look important but the unimportant things should be there to complement the important (what is important)

What is GIS?

It is a computerized system (most recent adaptation) used for assessing spatial info

What are the layers for map algebra?

Local Focal Zonal Global

What is the fourth principle of Krygiers 5 principles of map design?

Maximum information at minimum cost, how much information can be gleaned from the map at just a glance

Legend

Needs to clearly define the category break

Title

Needs to clearly define what, where, when is being mapped, prominently

Vector Data

Provides a way to represent real world features within the GIS environment. A feature has its shape represented using points, lines, and polygons, and TINs

Using reclassification and DEM, can you think of a data flow to go from a raster DEM to contour polygons?

Raster dem's are elevation data. Contours are vector lines showing elevation contours. So all elevations between 600 and 610 are bounded by a 600 and 610 contour lines. All raster values between these two lines are between these two numbers.You could test for values to be between 600 and 610 and give them one value. Likewise for all other intervals. That is how you get from a dem to a contour line. *this is off someone elses thing b/c i had no idea*

Topology

Set of rules that defines how point, line, and polygon features share coincident geometry. Describes means, whereby lines, borders, points meet up and cross.

What is the third principle of Krygiers 5 principles of map design?

Simplicity from sacrifice not what you put into the map but what you take out of it (less is more)

What elements of mapmaking are considered art?

Symbology , visual balance, color, and contrast

Visualization of raster

Table of pixels where each pixel is assigned a different value.

Annotation

Text that adds meaning to mapped features

Symbology

The art of expression, using graphics and text to convey meaning

How do maps lie?

They are subject to bias and only present certain information instead of all information

Why is topology important?

Topology keeps us from using bad data. When the rules of topology are violated, we cannot build. Important to GIS because it allows for functions like routing, stream flow, and traffic studies as well as allowing for automated error detection, elimination of error, and sharing features

Do larger scale maps show more detail than smaller-scale maps T/F

True

T/F A datum is REQUIRED to define any coordinate system

True

Projection coordinate systems we have used

Universal Transverse Mercator and Stane Plane Coordinate System

Neat Line

a box drawn around the map to give a "neat," or tidy, appearance to the product

Data

a collection of attributes, facts, measurements or statistics about entities

Experimental Data

apply treatments to experimental units and the proceed to observe the effect of the treatments on the experimental units

Direction/ angle

azimuthal measure in degrees fo angle from north, preserves direction On Earth: regular angle On Map: extended angle

Raster Data

cell or pixel based data

Metadata

data about data- all the facts you need to know about your data set

Secondary data

data collected by someone else earlier and re-used for other purposes

Definition of spatial data

data/information that identifies the geographic location of features and boundaries on Earth

To define a GCS, a ____ must be first chosen

datum

Disadvantages of Raster Data

large amount of data, less "pretty", different scales between layers

Geographic Coordinate System simply called

longitude and latitude