Geography Lecture 7: Map Projections

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Questions and Answers

What is a key characteristic of the Mercator projection?

It is best for mapping polar regions.

It preserves the shapes of areas. (correct)

It uses a spherical model instead of an ellipsoidal model.

It distorts distances equally across all areas.

What are the upper and lower latitude limits for cylindrical projections?

89° N and 89° S (correct)

45° N and 45° S

0° N and 0° S

90° N and 90° S

What is the main application of Web Mercator projection?

Large-scale terrestrial mapping.

Cadastral mapping of rural areas.

Conformal mapping of international borders.

Online mapping applications. (correct)

Which projection is suited for mapping areas from east to west and uses two standard parallels?

Lambert Conformal Conic Signup and view all the answers

How does the Universal Transverse Mercator minimize distortion?

By dividing the Earth into zones. Signup and view all the answers

In the State Plane Coordinate System, which projection is used for east to west zones?

Lambert Conformal Conic Signup and view all the answers

What is a projection file primarily used for?

Defining spatial reference of the data. Signup and view all the answers

What is the primary distortion type associated with the Web Mercator projection?

Area and distance distortions. Signup and view all the answers

What does the clip operation achieve in spatial data analysis?

Extracts a specific area of interest from features Signup and view all the answers

Which of the following best describes the difference operation in spatial data analysis?

Keeps only the portions of features outside the overlay layer Signup and view all the answers

What does the dissolve operation accomplish?

Consolidates features with the same value in a specified attribute field Signup and view all the answers

What type of output can result from spatial data analysis?

Either spatial layers or nonspatial outputs like tables Signup and view all the answers

What distinguishes a compound query from a simple query?

A compound query combines multiple conditions or variables Signup and view all the answers

Which Boolean operator would you use if you want to exclude records that meet certain conditions?

NOT Signup and view all the answers

Which of the following is NOT a type of spatial relation?

Overlap with threshold Signup and view all the answers

The major outcome of using the merge operation in spatial data is to:

Create a new feature class from multiple datasets Signup and view all the answers

What type of cylindrical projection is tangential to the Earth at the equator?

Equatorial/normal cylindrical projection Signup and view all the answers

Which of the following projections touches the globe at two standard parallels?

Secant cylindrical projection Signup and view all the answers

What term describes a projection that maintains the local shape of features across the map?

Conformal projection Signup and view all the answers

In a transverse cylindrical projection, where is the cylinder tangent to the Earth?

Along a line of longitude Signup and view all the answers

What are the two types of azimuthal projections based on the position of the plane?

Polar and oblique Signup and view all the answers

What is a basic parameter of a projection that ensures all x coordinates are positive?

False easting Signup and view all the answers

Which projection method is based on setting a plane tangential to a sphere?

Azimuthal projection Signup and view all the answers

What type of projection preserves the area of a feature across the map?

Equal area projection Signup and view all the answers

What do the terms record, field, and attribute refer to in an attribute table?

Record = rows, Field = columns, Attribute = non-spatial characteristics Signup and view all the answers

Which files are essential components of a shapefile?

.shp, .shx, .dbf Signup and view all the answers

What is the principle behind editing vector data?

To maintain topological integrity among features during updates Signup and view all the answers

What does class overlay entail in spatial data analysis?

Extracting new information by combining different thematic data layers Signup and view all the answers

How do intersect and union differ in their applications?

Intersect combines data only where both layers overlap, while union includes all data from both layers Signup and view all the answers

What defines a variable distance buffer?

A buffer with different distances assigned to individual features Signup and view all the answers

Which type of buffer identifies overlap within defined distances?

Compound buffer Signup and view all the answers

What is the main purpose of the clip operation in spatial analysis?

To extract a specific portion of one layer based on another Signup and view all the answers

What type of classification method involves groups data into classes with an equal number of features/values?

Quantile Signup and view all the answers

Which of the following principles should NOT be used when entering expressions in a field calculator?

Surround whole numbers with characters Signup and view all the answers

What is the smallest geographic unit available in the ACS 5-year data?

Block group Signup and view all the answers

Census tracts are optimally designed to contain approximately how many people?

4,000 Signup and view all the answers

What is one characteristic of decennial census data?

Highest geographic resolution Signup and view all the answers

Which data source provides complete geographic coverage for census tract scale?

Decennial census data Signup and view all the answers

Which of the following is NOT a feature of block groups?

Covers entire nation Signup and view all the answers

In U.S. census data, what does TIGER stand for?

Topologically Integrated Geographic Encoding and Referencing Signup and view all the answers

Which cardinality type represents a scenario where one feature attribute record can relate to many nonspatial records?

One to many Signup and view all the answers

What defines a primary key in database management?

A unique identifier for each record in a table Signup and view all the answers

In a one to many join, which statement is true about the relationship between the tables?

The target table has larger spatial units than the join table. Signup and view all the answers

What is the result of a many to one relationship during a table join?

A successful join that satisfies the join rule Signup and view all the answers

What characterizes a relate operation compared to a join operation?

It accommodates many to many relationships. Signup and view all the answers

Which scenario exemplifies a simple relationship between entities?

Connecting a city to its state name Signup and view all the answers

When distinguishing a personal geodatabase from an enterprise geodatabase, what is a notable difference?

Enterprise geodatabases support concurrent users. Signup and view all the answers

What is a major rule that must be satisfied for a join to be valid?

Each record in the target table must exactly match one record in the join table. Signup and view all the answers

What is the purpose of applying reclassification to a land use raster?

To reduce the number of classes displayed Signup and view all the answers

What is the output of a conditional function when the test condition is true?

It provides the output specified for true Signup and view all the answers

What drawback is associated with using Boolean overlay in spatial analysis?

It does not account for the importance of input layers Signup and view all the answers

In the context of weighted overlay, which factor is considered favorable for siting a landfill?

Low slopes Signup and view all the answers

What does masking accomplish in spatial analysis?

It identifies areas within a defined boundary Signup and view all the answers

How is clipping different from masking in spatial data operations?

Clipping extracts a specific area using a mask's shape Signup and view all the answers

What is a common approach used in the reclassification of land use rasters?

By creating unique values or categories Signup and view all the answers

Which condition must be met when using the AND operation in Boolean overlay?

Both conditions must be satisfied simultaneously Signup and view all the answers

What is the primary role of a primary key in a database?

To uniquely identify each row in a target table Signup and view all the answers

Which statement best describes continuous raster data?

It can include values like elevation and temperature. Signup and view all the answers

What does spatial resolution refer to in raster data?

The level of detail represented by the cell size Signup and view all the answers

Which resampling technique is considered the fastest?

Nearest neighbor Signup and view all the answers

Map algebra primarily involves which of the following?

Combining raster data layers using mathematical functions Signup and view all the answers

Which type of raster operation uses data from multiple cells to calculate output?

Neighborhood operation Signup and view all the answers

What is a key characteristic of reclassification in raster analysis?

It assigns new output values based on specific input value sets. Signup and view all the answers

What is a foreign key used for in a database context?

To facilitate the relational link between two tables Signup and view all the answers

Which type of raster data can have an attribute table?

Land use data Signup and view all the answers

What effect does a finer resolution have on accuracy in raster data?

Does not improve accuracy Signup and view all the answers

Which method of resampling is known for being the slowest?

Cubic convolution Signup and view all the answers

What type of operation uses data from a single cell in raster analysis?

Local operation Signup and view all the answers

What describes spatial resolution in relation to raster data?

It is inversely proportional to scale Signup and view all the answers

Which of the following operations is NOT considered part of map algebra?

Data formatting Signup and view all the answers

What type of analysis uses all data from a raster layer?

Global analysis Signup and view all the answers

In resampling techniques, which method is used primarily for discrete data and does not alter cell values?

Nearest neighbor Signup and view all the answers

What is a characteristic of a personal geodatabase?

Is limited to a single user and tied to a specific file format Signup and view all the answers

Which type of relationship involves a feature attribute record relating to multiple nonspatial records?

One to many Signup and view all the answers

Which condition must be met for a valid join between tables?

Each record in the target table matches one and only one record in the join table Signup and view all the answers

What is the key difference between a join and a relate operation?

Joins require matching records in both tables, while relates do not Signup and view all the answers

Which cardinality type describes many feature attribute records relating to one nonspatial record?

Many to one Signup and view all the answers

In which situation would a one-to-many join not satisfy the rule of join?

When the target table has larger spatial units than the join table Signup and view all the answers

Which statement is true about complex relationships in a database?

Complex relationships can occur between both spatial and nonspatial objects Signup and view all the answers

What distinguishes an enterprise geodatabase from other types?

It supports multi-user and multi-level data access Signup and view all the answers

What is the primary purpose of reclassification in land use analysis?

To simplify and reduce the number of classes displayed in a land use raster Signup and view all the answers

Which function correctly describes a conditional expression?

Output = CON(condition, outcome if true, outcome if false) Signup and view all the answers

What does the Boolean overlay technique accomplish in spatial analysis?

It only includes areas where all conditions are met Signup and view all the answers

What is a significant drawback of using Boolean overlay in spatial analysis?

It assumes all input layers are of equal importance Signup and view all the answers

How does a weighted overlay differ from a standard overlay in spatial analysis?

It ranks the importance of various conditions Signup and view all the answers

What is the primary function of masking in GIS?

To define areas of interest using a binary layer Signup and view all the answers

What steps are involved in clipping a raster using a mask?

Choose a mask layer, apply it to the raster using GIS tools Signup and view all the answers

What are the implications of choosing an area with low soil infiltration in the context of landfill siting?

It prevents leaching of contaminants into groundwater Signup and view all the answers

Study Notes

Lecture 7: Map Projections

Major types of projections based on projection surface: cylindrical, conic, and azimuthal
Equatorial/normal cylindrical projection: tangent to the Earth at the equator
Transverse cylindrical projection: cylinder rotated sideways, tangent along a line of longitude
Oblique cylindrical projection: tangent at an angle (skew axis)
Tangent cylindrical projection: cylinder tangent to the globe along a parallel
Secant cylindrical projection: cylinder placed through the globe touching two parallels

Lecture 7: Conic Projections

Tangent conic projections: cone aligns with one pole
Secant conic projections: cone placed through the globe
Same as cylindrical, but the setting is a cone (cone point aligns with a pole)

Lecture 7: Azimuthal Projections

Based on setting a plane tangent or secant to the sphere
Polar Azimuthal: plane centered on a pole
Oblique Azimuthal: plane at an angle

Lecture 7: Basic Projection Parameters

Standard parallels
Central meridian (x=0)
Latitude of origin (y=0)
False easting
False northing

Lecture 7: Mercator Projection

Cylindrical projection (north and south = up and down)
Conformal (preserves shapes)
Distorts area (areas closer to the equator are more accurate)
Useful for large-scale mapping near the equator

Lecture 7: Web Mercator Projection

Uses spherical model instead of ellipsoidal
Used by online mapping (e.g., Google Maps)
Has area and distance distortions
EPSG 3857

Lecture 7: Lambert Conformal Conic Projection

Based on 2 standard parallels
Best for conformal mapping of land masses (east to west)
Meridians converge at the poles
Albers is the same but preserves area rather than shape
Both poles are represented as arcs

Lecture 8: Tables

Data structure to store attributes
Standalone tables: store tabular data from any source (independent of geographic datasets)
Attribute tables: store data associated with spatial features

Lecture 8: Attribute Table Components

Record = rows
Fields = columns
Attribute = non-spatial characteristics associated with spatial data

Lecture 8: Shapefiles

Collection of geographic features sharing the same geometry type
Consists of .shp (main file), .shx (index file), and .dbf (dBASE table)

Lecture 9: Buffers

A region less than or equal to a specified distance from features
Point layer, Simple buffer, Compound buffer, Nested buffer
Variable distance buffer: each feature assigned a different buffer distance

Lecture 9: Overlay Operations

Intersect: combines data from both layers where they overlap, only overlaps
Union: overlays all data (including attribute data) from the counting and input layers (no geographic or attribute data discarded)
Different overlay operations use appropriate geographic or attribute data

Lecture 9: Spatial Data Analysis

Operations on spatial and attribute data to solve problems
Outputs can be spatial (new layer) or nonspatial (scalar value, list, table)

Lecture 10: Clip and Difference

Clip: extracts an area of interest from features; used as a cookie cutter
Difference: input layer features that partially overlap, retaining only the portions outside the overlay

Lecture 10: Dissolve and Merge

Dissolve: removes boundaries of features with the same value in the specified attribute field
Merge: combines adjacent feature classes.

Lecture 10: Spatial Data Analysis

Operations on spatial and attribute data to solve problems
Outputs can be spatial (new layer) or nonspatial (scalar value, list, table)

Lecture 10: Query

Selection of records based on values of specified attributes
Simple query = single variable
Compound query = conditions/multiple variables

Lecture 10: Spatial Selection

Based on spatial relationships to other geographic features
Spatial relationship types include intersect, are within, contain, disjoint, equal, and touch

Lecture 10: Classification

Binary classification (0 and 1, true and false)
Equal-interval (highest-lowest)
Natural breaks
Quantile
Equal area
Standard deviation

Lecture 10: Census Data

TIGER (Topologically Integrated Geographic Encoding and Referencing) data describes U.S. census data
Levels of nested geography, including country, region, division, state, county, census tract, block group, and census block.
Topological Integrated Geographic Encoding and Referencing (TIGER) data:
Census tract scale, complete geographic coverage

Lecture 10: Smallest Geography in ACS 5-Year Data

Block group

Lecture 10: Decennial Census Data Characteristics

Population data by sex, race, age
Housing data

Lecture 10: GEOID

Numeric codes uniquely identify administrative/legal and statistical geographic areas for tabulation.

Lecture 10: Density Maps

Visual representation of a variable's distribution and intensity (e.g., population density)
Color gradients or contours
Useful in geographic analysis

Lecture 10: Heatmaps

Search radius and cell size determine detail level
Trade-off between detail and processing time/file size (large size = more detail)

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Description

This quiz covers the major types of map projections, including cylindrical, conic, and azimuthal projections. Participants will explore the characteristics of each projection type, focusing on their settings and parameters. Learn how these projections are applied in geographic studies and cartography.