Lecture 2

Question 1

What is the purpose of accuracy assessment in classification?

Answer 1

To evaluate how well a classified map represents real-world land cover

Question 2

What is the statement highlighting the importance of accuracy assessment?

Answer 2

“Without an accuracy assessment, a classified map is just a pretty picture.”

Question 3

What is the first step in accuracy assessment?

Answer 3

Collecting reference or “ground truth” data

Question 4

What is the second step after collecting reference data?

Answer 4

Comparing reference data to the classified map to check agreement

Question 5

What are common sources of reference data for accuracy assessment?

Answer 5

Aerial photo interpretation, GPS ground plots, and GIS layers

Question 6

Why might aerial photos be unsuitable as reference data?

Answer 6

They may lack the detail needed to distinguish closely related classes (e.g., species of grass)

Question 7

Why might GPS plots be unsuitable for large pixels (e.g., 1 km)?

Answer 7

They may be too small relative to the resolution of the classified image

Question 8

How is total accuracy calculated?

Answer 8

Number of correct plots divided by total number of plots

Question 9

What is a key limitation of total accuracy?

Answer 9

It averages all errors and hides class-specific performance differences

Question 10

What does user’s accuracy measure?

Answer 10

Error of commission (incorrect inclusions in a class)

Question 11

What does producer’s accuracy measure?

Answer 11

Error of omission (items of a class left out or misclassified)