Deck 12: Raster Data Analysis

Question 1

Map algebra is limited to the use of a single layer as the input.

Answer 1

False

Question 2

Which of the following statements is not true about a block operation?

A) A block operation does not move from cell to cell, but from block to block.
B) A block operation assigns the calculated value to all cells in a block.
C) None of these are correct
D) A block operation is similar to a neighborhood operation.

Answer 2

None of these are correct

Question 3

Explain 'reclassification' as a method for creating new raster data.

Answer 3

No Answer

Question 4

Which of the following statistics cannot be used in a neighborhood operation?

A) minority
B) majority
C) maximum
D) mean
E) none of these are correct

Question 5

A zonal operation on a single input raster produces measures of the zonal geometry.

Question 6

A neighborhood operation on a raster requires the focus cell to move from one cell to another until all cells are visited.

Question 7

You have downloaded from the Internet an elevation raster, which has values ranging from 94.7 to 2409.1 meters. But, for your project, you need a new integer raster with elevation values grouped into five classes: 1 (0-500), 2(500-1000), 3(1000-1500), 4(1500-2000), and 5(2000-2500). Describe how you can complete the task.

Question 8

What is the function of an analysis mask in raster data operations?

Question 9

Which of the following statistics is appropriate for use with categorical data?

A) Sum
B) Mean
C) Median
D) Majority

Question 10

Illustrate with a diagram a 3-by-3 neighborhood mean operation.

Question 11

Which local operation can assign a unique output value to each unique combination of cell values from multiple rasters?

A) Reclassify
B) Merge
C) Combine
D) Add

Question 12

What types of neighborhoods can be used in a neighborhood operation?

Question 13

A zone in raster data operation may consist of contiguous cells or separate regions of cells.

Question 14

To define a riparian zone, a government agency will most likely use a vector-based buffering operation, rather than a raster-based physical distance measure operation. Why?

Question 15

The following diagram shows a raster with its origin (0, 0) at the upper left corner. Suppose that the raster is used for a couple of 3-by-3 neighborhood operations. (1) What is the range statistic for (col. 3, row3)? (2) What is the majority statistic for (col. 3, row3)? (3) What is the variety statistic for (col. 3, row3)?

Question 16

The cell value of 'no data' is treated as zero in raster data operations.

Question 17

Which of the following mathematical functions can be used for local operations?

A) all of these are correct
B) arithmetic
C) trigonometric
D) both arithmetic and logarithmic
E) logarithmic

Question 18

Which of the following can be used as a neighborhood in raster data operation?

A) All of these are correct
B) A 3x3 rectangle
C) Both a 3x3 rectangle and a 5x5 rectangle
D) A circle
E) A 5x5 rectangle

Question 19

A local operation is limited to only two input rasters.

Question 20

Define "map algebra" for raster data analysis.

Question 21

How does a local operation differ from a neighborhood operation?

Question 22

We must manually convert all input rasters to the same cell size before using them in ArcGIS for a raster data operation.

Question 23

Use a diagram to illustrate how the Aggregate operation works.

Question 24

Explain how physical distance measures are calculated in a raster data operation.

Question 25

An analysis mask limits analysis to cells that do not carry the cell value of 'no data.'

Question 26

If a zonal operation involves two rasters, one of the rasters must be defined as the zonal raster. What is a zone?

Question 27

Which of the following can be used to specify the area extent for analysis?

A) a specified raster
B) an area defined by its minimum and maximum values inx- andy-coordinates
C) an analysis mask
D) both a specified raster and an analysis mask
E) all of these are correct

Question 28

You have a slope raster and an aspect raster. The slope raster has 3 values: 1 for 0-20%, 2 for 20-40%, and 3 for >40%. The aspect raster has 5 values: 1 for flat area, 2 for north, 3 for east, 4 for south, and 5 for west. Describe the procedure you will follow to locate those areas with 20-40% slope and the south aspect.

Question 29

The output from a 5x5 neighborhood operation will be _________ the output from a 3x3 neighborhood operation:

A) the same as
B) less generalized than
C) more generalized than

Question 30

Suppose you are asked to produce a raster that shows the average precipitation in each major watershed in your state. Describe the procedure you will follow to complete the task.

Question 31

Which of the following can be used to extract data from an existing raster in ArcGIS?

A) a circle
B) a query expression
C) a polygon shapefile
D) both a circle and a query expression
E) all of these are correct

Question 32

A zonal operation can be run with one input raster or two input rasters. How do these two types of zonal operations differ in terms of their applications?