Geographic Projections and Tables
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Questions and Answers

What type of projection is described as placing a cylindrical surface tangent to the Earth at the equator?

  • Transverse cylindrical projection
  • Secant cylindrical projection
  • Normal cylindrical projection (correct)
  • Oblique cylindrical projection

Which projection type features a cone that aligns with one of the poles?

  • Azimuthal projection
  • Conic projection (correct)
  • Cylindrical projection
  • Equatorial projection

In which type of cylindrical projection are there two standard parallels due to the cylinder passing through the globe?

  • Normal cylindrical projection
  • Secant cylindrical projection (correct)
  • Tangent cylindrical projection
  • Transverse cylindrical projection

What is a defining characteristic of conformal projections?

<p>They maintain local shapes of features across the map. (B)</p> Signup and view all the answers

What type of azimuthal projection is centered at one of the poles?

<p>Polar azimuthal projection (A)</p> Signup and view all the answers

Which parameter of a projection represents the meridian that is close to the center of the map?

<p>Central meridian (A)</p> Signup and view all the answers

What is the purpose of false easting in a map projection?

<p>To ensure all x coordinates are positive. (C)</p> Signup and view all the answers

Which type of projection is best known for preserving the area of features across a map?

<p>Equal area projection (A)</p> Signup and view all the answers

What is the primary purpose of an attribute table?

<p>To store data associated with a spatial feature class (D)</p> Signup and view all the answers

Which of the following file formats is NOT required to compose a shapefile?

<p>.idx (B)</p> Signup and view all the answers

What is required when editing vector data to maintain data integrity?

<p>Updating existing feature classes or creating new ones while maintaining topological integrity (A)</p> Signup and view all the answers

Which description best fits the concept of class overlay?

<p>Combining spatial and attribute data from multiple data layers (D)</p> Signup and view all the answers

How does the intersection operation differ from the union operation in GIS?

<p>The intersection includes only overlapping data while the union includes all data (C)</p> Signup and view all the answers

What characteristic of the Mercator projection affects its accuracy near the poles?

<p>Preserves shapes but distorts areas (D)</p> Signup and view all the answers

What does a variable distance buffer do in GIS?

<p>Applies different buffer distances to different features based on a field (B)</p> Signup and view all the answers

What is a primary application of the Web Mercator projection?

<p>Online mapping applications like Google Maps (C)</p> Signup and view all the answers

Which type of buffer is described as having overlap identified?

<p>Compound buffer (A)</p> Signup and view all the answers

What is the main focus when performing the clip operation in GIS?

<p>Removing excessive data while retaining specific portions of features (B)</p> Signup and view all the answers

What difference sets Lambert Conformal Conic projection apart from Albers projection?

<p>Best suited for mapping land masses from east to west (B)</p> Signup and view all the answers

How does the Universal Transverse Mercator handle distortion?

<p>No distortion along the central meridian (B)</p> Signup and view all the answers

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

<p>Lambert Conformal Conic (C)</p> Signup and view all the answers

What is the purpose of a projection file in geographic information systems?

<p>To transform geographic coordinates to Cartesian coordinates (A)</p> Signup and view all the answers

What is the effect of using a spherical model in Web Mercator projection?

<p>Creates more significant area and distance distortions (B)</p> Signup and view all the answers

What are the latitude limits for the Universal Transverse Mercator projection?

<p>84° N to 80° S (B)</p> Signup and view all the answers

What is the primary characteristic of census tracts?

<p>They are consistent statistical divisions of a county. (A)</p> Signup and view all the answers

Which of the following represents a method for classifying data into quantiles?

<p>Groups data into classes with an equal number of features. (A)</p> Signup and view all the answers

Which of the following statements about block groups is correct?

<p>Block groups are the smallest units for tabulation of sample data. (C)</p> Signup and view all the answers

What is a characteristic of decennial census data?

<p>It includes data about the housing status of the population. (D)</p> Signup and view all the answers

How should operators be treated in a field calculator expression?

<p>Operators should be placed without any special formatting. (B)</p> Signup and view all the answers

What is the smallest geography for ACS 5-year data?

<p>Block group. (A)</p> Signup and view all the answers

What does the dissolve operation accomplish in spatial data analysis?

<p>Removes boundaries of features with the same value in a specified attribute field (B)</p> Signup and view all the answers

Which of the following is true regarding TIGER data?

<p>It uses levels of nested geography for organization. (A)</p> Signup and view all the answers

Which outcome is generated from spatial data analysis?

<p>New spatial layers or scalar values (B)</p> Signup and view all the answers

What type of value should be entered in the field calculator without any surrounding characters?

<p>Whole numbers and decimal numbers. (A)</p> Signup and view all the answers

What type of query restricts the selection of records by decreasing the number of instances returned?

<p>AND query (B)</p> Signup and view all the answers

In spatial selection, which of the following describes the 'Contains' relationship?

<p>Fully within another feature (D)</p> Signup and view all the answers

How does a merge operation differ from a dissolve operation in spatial data analysis?

<p>Merge combines features from 2 or more datasets; dissolve removes internal boundaries (C)</p> Signup and view all the answers

Which Boolean operator would you use to filter records that do not match a given criterion?

<p>NOT (B)</p> Signup and view all the answers

Which spatial relation means that two features do not overlap or touch each other?

<p>Disjoint (B)</p> Signup and view all the answers

What defines a compound query compared to a simple query in spatial data analysis?

<p>Uses multiple variables or conditions (D)</p> Signup and view all the answers

Flashcards

Cylindrical Projections

Map projections where a cylinder is wrapped around the Earth, creating map representations.

Equatorial/Normal Cylindrical Projections

Cylindrical projections where the cylinder is tangent to the Earth at the equator.

Transverse Cylindrical Projections

Cylindrical projections where the cylinder is tangent to the Earth along a line of longitude, rotated sideways.

Azimuthal Projections

Map projections based on a plane tangent or secant to a sphere.

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Standard Parallels (Projection)

Parallels of latitude on a map projection where shapes are accurately represented.

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Conformal Projection

A map projection that preserves the shape of features across the map.

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Equal-Area/Equivalent Projection

A map projection that preserves the area of features across the map.

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Mercator Projection

A cylindrical map projection that distorts areas, especially near the poles.

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Attribute Table Record

A row in an attribute table, representing one instance of a feature.

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Shapefile

A collection of geographic features (points, lines, polygons) with associated attributes.

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Editing Vector Data

Updating or creating geographic features while maintaining their relationships.

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Class Overlay

Combining data from multiple layers to analyze common features.

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Intersect

Overlay that creates new features from the area where two layers overlap.

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Union

Overlay that combines all areas from two layers.

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Buffer

A zone around geographic features, defined by a distance.

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Variable Distance Buffer

A buffer with different distances for different features.

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Web Mercator

A cylindrical projection used in online maps (like Google Maps), using a spherical model, causing distortions in area and distance, with a standard EPSG code (3857).

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Lambert Conformal Conic

A map projection based on two standard parallels, ideal for conformal (shape-preserving) mapping of landmasses extending from east to west, where meridians converge at the poles.

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Universal Transverse Mercator (UTM)

A projection dividing the Earth into 6° longitude zones, extending from 84°N to 80°S. Accurate along central meridian, best for local, country, or small state maps.

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State Plane Coordinate System

A system using Transverse Mercator or Lambert Conformal Conic projections to map states, with N-S zones using Transverse Mercator and E-W zones using Lambert Conformal Conic. Larger states use multiple zones for accuracy.

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Projection File

A file used to define a Spatial Reference, transforming geographic coordinates to cartesian coordinates or changing between projected coordinate systems.

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Table

A structured set of data organized into rows and columns.

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Map Projection

A way of representing the curved surface of the Earth on a flat map. This process always causes some distortion, either of shape, area, distance or direction.

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Clip (Spatial Data Analysis)

Extracts a specific area of interest from features, defining the output area.

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Difference (Spatial Data Analysis)

Keeps only the parts of features that are outside the overlaying features.

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Dissolve (Spatial Data Analysis)

Removes boundaries of features with matching attribute values.

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Merge (Spatial Data Analysis)

Combines multiple feature datasets into one new dataset.

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Spatial Data Analysis

Applies operations to spatial and attribute data to solve problems

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Query (Spatial Data Analysis)

Selects records based on the attributes' values (Filtering)

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Spatial Selection

Selection based on spatial relationships between features.

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Spatial Relationships (Intersect, Within, etc.)

Different ways features relate spatially (overlap, contain, disjoint).

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What are some principles to use expressions in field calculator?

When writing expressions in field calculator, operators should be placed without any special formatting. Fields should be surrounded by double quotes. Text values should be surrounded by single quotes. Integers and floats should be entered without any special formatting.

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TIGER Data

Topologically Integrated Geographic Encoding and Referencing data, a database of geographic features from the US Census Bureau.

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Census Tract

A small, permanent, and consistent statistical division of a county. It's designed to contain approximately 4,000 people.

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Block Group

The smallest unit for tabulating sample data in the American Community Survey, with a population ranging from 600 to 3,000 people.

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Census Block

The smallest geographic unit for tabulating data in the US Census. It covers the entire nation and nests within other geographic areas, with an average of 100 people per block.

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What are some examples of decennial census data?

The decennial census collects data on topics including population by sex, race, and age; Hispanic origin; housing occupancy, vacancy status, and tenure.

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What is the smallest geography in ACS 5-year data?

Block group is the smallest geography in ACS 5-year data.

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What is GEOID?

GEOID is a unique identifier used for geographic areas in the US Census Bureau's data, consisting of a combination of state, county, tract, and block group codes.

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Study Notes

Lecture 7

  • Major projection types based on surface: cylindrical, conic, azimuthal
  • Equatorial/normal cylindrical projection: tangent to Earth at the equator
  • Transverse cylindrical projection: rotates the cylinder sideways to be tangent along a line of longitude
  • Oblique cylindrical projection: tangent at an angle (skew axis)
  • Tangent cylindrical projection: cylinder is tangent to the globe along a parallel
  • Secant cylindrical projection: cylinder passes through the globe touching it at two points; has two parallels

Lecture 8

  • Table definition: a data structure for storing attributes
  • Standalone tables: store attributes independent of geographic datasets
  • Attribute tables: store data describing a spatial feature class
  • Record, Field, and Attribute: record = row, field = column, attribute = nonspatial characteristic
  • Shapefile definition: collection of geographic features with the same geometry type
  • Shapefile file formats: .shp (main), .shx (index), .dbf (dBASE table)

Lecture 9

  • Buffer definition: area within a specified distance of one or more features
  • Point layer: single feature
  • Simple Buffer: dissolved, no intersection
  • Compound Buffer: multiple overlaps, identified
  • Nested Buffer: features include each other's features
  • Variable Distance Buffer: each feature has a different distance
  • Buffer applications: agriculture, farming based on distance needs

Lecture 10

  • Spatial Data analysis outputs: spatial and attribute data output, can be a new layer or scalar value
  • Query and Simple/Compound Queries: Selection based on attributes (variables)
  • Basic Boolean operators: AND (restrictive), OR (inclusive), NOT (negative space)
  • Spatial relations: based on geographic relationships
  • Common classification methods: binary, equal-interval, natural breaks, quantile, equal area, standard deviation
  • Principles of field calculator expressions: surround text by single or double quotations, use any desired formatting for numerical data
  • US Census data: source, geographies, TIGER system (Topologically Integrated Geographic Encoding and Referencing), levels of nested geography (country, region, division, state, county, census tract, block group, census block), lowest level data
  • Smallest geography in ACS 5-year data: block group
  • Decennial Census data characteristics: population by sex, race, age, and Hispanic origin, housing data
  • Characteristics of census tracts, block groups, and blocks: divisions in a county.
  • Density maps: visual display of distribution and intensity of a variable
  • Search parameters: radius, cell size, and trade-offs for detail/coarseness of results

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Study Guide for Quiz 2 (Lectures 7-10) PDF

Description

This quiz covers key concepts from Lecture 7 and Lecture 8 on geographic projections and attribute tables. You'll explore different projection types such as cylindrical and how tables are used in storing geographic data. Test your knowledge on understanding shapefiles and their attributes.

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