Chapter 10 - Topics in Raster Analysis Flashcards
This data model is based on a 2D array of cells
Raster data model
In the raster data model, each cell is assigned this
Single value
What are at least three of four ways in which the raster data model is highly flexible?
- Easy to code in computer language; 2. Cells can store all data types; 3. Can be directed to many problems; 4. Complex structures can be built
What are at least three of four types of time-varying and continuous phenomenon that the raster data model is useful for?
- Elevation; 2. Surface temperature; 3. Rainfall; 4. Soils
What are three of four examples of GIS data types that are in raster format?
- DRG; 2. DEM; 3. NLCD; 4. Remote sensing
Is the raster data model a relatively new data structure?
No
Are there extensive analytical tools developed for the raster data model?
Yes
Do many raster tools share the same conceptual basis?
Yes
This input layer function uses a single layer
Unary
This input layer function uses two layers
Binary
This input layer function uses > 2 layers
Higher-ordered
This input scope function uses values at each cell loci
Local function
This input scope function uses values in a defined area around output cell loci
Neighborhood function
This input scope function uses values from user-defined zones
Zonal function
This input scope function manipulates input from entire layer
Global function
What are the four classes of local operations?
- Mathematical; 2. Logical; 3. Classification; 4. Overlay
This class of local operations uses standard arithmetic
Mathematical functions
What are at least four of six examples of mathematical functions?
ABS, LN, COS, TRUNC, SQRT, POWER
This class of local operations is for ordinal and equality tests
Logical functions
Logical functions are for finding these values
Non-zero and non-null values
What are the three basic logical operations?
And, or, not
This logical function means “exclusive or” - true only if one of the layers has value
XOR
This logical function is for missing values
ISMISSING (ISNULL)
This local function assigns output values for a set of input values
Classification function
What are three things that can define outputs in classification functions?
Table, ranges, or conditional tests
In classification using a conditional test, output = this
CON (test, out if true, out if false)
What value are unmatched values assigned in classification functions?
Null value
What are the two types of overlay functions?
Union and clip + intersect
This overlay function is a cell by cell combination of cell values
Union
In union function, each combination is given this
Unique identifier
What type of attribute table does a union function create?
Many-to-one
What type of data is used most often with union function?
Nominal data
In this type of union function, the user specifies source and template layer
Clip and intersect
In the clip and intersect function, this picks source values for output
Template
In clip and intersect function, if the template = 1, what is the output?
Source
In clip and intersect function, if the template = 0, what is the output?
Null
These functions use input from a defined set of cells
Neighborhood function
What do maps result in from neighborhood functions?
One cell in output
This defines the neighborhood in neighborhood functions
User
How many cells do neighborhood functions typically result in?
9 cells
What are two types of data typically used with neighborhood functions?
Interval or ratio data
Many neighborhood functions use this positioned over an input location to specify an area of input cells
Moving window
A moving window is defined by this for many functions
Kernel
What is a moving window kernel?
Set of constants for cells in window
What are at least three of four examples of common kernels?
- Nbrhood mean; 2. Data smoothing; 3. Edge detection; 4. Noise detection
These operations are functions applied to user-defined areas in input layer
Zonal operations
Can zones be irregularly shaped?
Yes
Zones are usually coded in a zone layer using these
Identifiers
What are at least two of four examples of zonal identifiers?
- Population by county; 2. Wood volume by forest tract; 3. Mean crop yield by state; 4. Highest elevations of a park
Many problems in raster analysis need analysis of this
Travel cost
What are two ways cost of travel is viewed in raster?
- Money/time costs; 2. Probability of spread
Travel cost analyses use these operations
Cost surface
What is another name for cost surface?
Friction surface
Total travel cost is a function of these two things
Distance travelled and travel cost through travelled areas
How is travel distance measured in raster?
Cell center to cell center
What are two ways to calculate distance in raster?
- Euclidean distance; 2. Row/column distance (city block)
What are two different types of cost surface?
- Uniform cost surface; 2. Variable cost surface
In this type of cost surface, moving through any cell has the same cost
Uniform cost surface
In uniform cost surface, the total cost is a product of this
Travel distance x uniform cost
In this type of cost surface, different cells have different travel costs
Variable cost surface
In variable cost surface, this determines the portion of the route passing through each cell
Total cost
