Chapter 9 - Basic Spatial Analyses Flashcards
This is a key role of GIS
Geospatial analysis
Geospatial analysis relies on these two types of data to answer questions
Coordinate and attribute data
How many GIS spatial operations are available?
Hundreds
What are four ways analytical output can be represented?
Single number, list, table, map layer
Where is the challenge in applying spatial data analysis operations?
Applying the correct operations in the correct order
Can some operations be applied to both vector and raster data?
Yes
Do the same conceptual operations always produce the same results in both vector and raster data?
No
Can large projects require many inputs and operations?
Yes
This is an area of input for an output location
Input scope
What are three levels of input scope?
Local, neighborhood, global
This input scope links point to point
Local
In this input scope, adjoining regions provide input
Neighborhood
In this input scope, an entire layer is used as an input
Global
This spatial analysis operation selects map features based on some criteria
Selection
What are two things that selection can select on?
Spatial properties or attributes
Selected features can be exported to this
New layer
This is the simplest form of selection that selects features or record by mouse cursor
On-screen query
This form of selection uses set algebra for select features based on attribute, and uses symbols (=, <>, <, >) and boolean logic
Select by attributes
This form of selection selects features on spatial properties
Select by location
This selects features that touch other features
Adjacency
This identifies features that contain target features
Containment
This spatial analysis operation assigns features to categories based on certain criteria
Classification
This can also be used to group features for display, using different symbology applied to different groups
Classification
Classification is often combined with this type of operation
Selection operation
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?
- 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?
- 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?
- 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?
No
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?
- 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?
- 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
