Chapter 9 - Basic Spatial Analyses Flashcards by FRANCES CASALINO

This is a key role of GIS

Geospatial analysis

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Geospatial analysis relies on these two types of data to answer questions

Coordinate and attribute data

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How many GIS spatial operations are available?

Hundreds

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What are four ways analytical output can be represented?

Single number, list, table, map layer

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Where is the challenge in applying spatial data analysis operations?

Applying the correct operations in the correct order

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Can some operations be applied to both vector and raster data?

Yes

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Do the same conceptual operations always produce the same results in both vector and raster data?

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Can large projects require many inputs and operations?

Yes

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This is an area of input for an output location

Input scope

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What are three levels of input scope?

Local, neighborhood, global

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This input scope links point to point

Local

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In this input scope, adjoining regions provide input

Neighborhood

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In this input scope, an entire layer is used as an input

Global

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This spatial analysis operation selects map features based on some criteria

Selection

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What are two things that selection can select on?

Spatial properties or attributes

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Selected features can be exported to this

New layer

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This is the simplest form of selection that selects features or record by mouse cursor

On-screen query

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This form of selection uses set algebra for select features based on attribute, and uses symbols (=, <>, <, >) and boolean logic

Select by attributes

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This form of selection selects features on spatial properties

Select by location

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This selects features that touch other features

Adjacency

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This identifies features that contain target features

Containment

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This spatial analysis operation assigns features to categories based on certain criteria

Classification

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This can also be used to group features for display, using different symbology applied to different groups

Classification

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Classification is often combined with this type of operation

Selection operation

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In this type of classification, the user specifies classification schema

Manual classification

These two things are specified in manual classification

Source input layer and input values

In manual classification, output class values are often applied using this

Classification table

What is a disadvantage of manual classification?

Time-consuming

This type of classification uses automated rules to create output values

Automated classification

Automated classification is typically used for this type of data

Quantitative data

These are used to define classes in automated classification

Math algorithms

Automated classification sacrifices this for speed

Precise control

What are four types of classification algorithms?

1. Equal interval; 2. Quantile; 3. Natural break; 4. Standard deviation

In this classification algorithm, the value range is the same in each class

Equal interval

In this classification algorithm, classes are divided so each has an equal number of features

Quantile

In this classification algorithm, classes are determined by clusters and gaps in data

Natural breaks

In this classification algorithm, classes are determined by relation to mean value

Standard deviation

This spatial analysis operation aggregates features in a layer that have the same attribute values

Dissolve

The dissolve operation does these two things

Creates new layer and removes shared boundaries

Dissolve may result in the creation of these

Multipart features

Dissolve is useful for this

Removing unneeded spatial/attribute data

This spatial analysis operation addresses questions of distance

Proximity

Proximity analysis uses these principles to calculate distance

Pythagorean principles

How is distance measured between raster cells?

Cell center to cell center

Proximity operations use this type of proximity function

Simple distance function

This proximity function finds distance from points on a map to a feature

Simple distance function

What do simple distance functions present values as?

Raster layer

These principles are used to measure distance from raster cell to raster cell

Pythagorean principles

This proximity function creates zones of a specified distance around chosen features

Buffering

Can buffers be used with both vector and raster data?

Yes

This type of buffering combines distance and classification to produce a 'stair-step' boundary

Raster buffering

What are the four types of buffering with vector data?

1. Simple buffering; 2. Compound buffering; 3. Nested buffering; 4. Variable distance buffering

This type of vector buffering buffers with a fixed distance from feature

Simple buffering

This type of vector buffering identifies an area that overlaps at least 2 features

Compound buffering

This type of vector buffering creates concentric buffers of increasing size

Nested buffering

This type of vector buffering uses differing buffer sizes for different features

Variable distance buffering

This spatial analysis operation takes spatial and attribute data from multiple layers and combines it into a single output layer

Overlay

What kind of problems is overlay used for?

Complex problems

This type of overlay is a cell by cell combination of at least 2 input layers

Raster overlay

Input raster layers must be this to perform raster overlay

Compatible

Raster layers may require this to be made compatible for raster overlay

Resampling

This type of overlay merges coordinate and attribute data from two vector layers

Vector overlay

What are three ways the topology of an output layer will change with vector overlay?

1. Split lines/polygons; 2. Addition of new nodes; 3. Change of adjacencies

Can any vector feature be overlain over any other vector feature?

Yes

Are all vector overlays useful and commonly used?

What are three common types of vector overlay operations?

Clip, intersect, union

Vector overlays can create these that add superfluous coordinate and attribute data

Sliver polygons

What are three ways to remove sliver polygons?

1. Redraw polygons with common boundary; 2. Manually remove slivers; 3. Use snapping on boundaries

These are sets of connected features

Networks

What are four examples of networks?

Roads, railroads, communication, utilities

Features are often termed this in networks

Centers

Centers are connected by these in networks

Links

Resources flow from these to these centers via links

Supply centers to demand centers

This is used in many network problems, measuring the cost of moving a resource through a link

Transit cost

What are three examples of units that transit costs can be measured with?

Distance, time, monetary units

This field of study explores the flow of resources through a network

Network analysis

What are three network analysis functions?

1. Route selection; 2. Resource allocation; 3. Traffic management

This network analysis function identifies the best route with the lowest total cost given constraints

Route selection

Finding the best route in route selection is this type of process

Recursive process

This network analysis function apportions territories to centers

Resource allocation

This network analysis function identifies bottlenecks, transit times and alternative routes, and is used to model possible changes to network structure

Traffic management

This is the process of spatially referencing street features with address information

Geocoding

Geocoding uses these two types of data

Zipcode and street address data

Geocoding address information includes this information for street line segments to make guesses as to location

Address range information