Remote Sensing Week 13: Accuracy & Classification

What does accuracy refer to in the context of remote sensing?

The level of detail of the measurement
The proportion of agreement between a classified map and the reference data (correct)
The thematic precision of the mapped data
The spatial resolution of the data set

What type of accuracy refers to how well the class name on the map corresponds to what is really on the ground?

Spatial Accuracy
Thematic Accuracy (correct)
Precision
Map Accuracy

What is the term for the data collected in the field to assess accuracy?

Spatial Data
Ground-Truth Data (correct)
Reference Data
Thematic Data

What is the relationship between accuracy and precision?

There is an inverse relationship between them (C) Signup and view all the answers

What is spatial accuracy related to?

The spatial resolution of the data set (D) Signup and view all the answers

What is an example of a map with high thematic precision?

A map distinguishing Lodgepole pine, Douglas fir, Ponderosa (D) Signup and view all the answers

What is a potential drawback of using reference data in geospatial analysis?

It may not accurately represent the actual conditions on the ground. (A) Signup and view all the answers

What is the purpose of comparing the classified data to the reference data?

To determine the accuracy of the classification. (A) Signup and view all the answers

What type of array is used to create an error matrix?

An (n x n) array. (B) Signup and view all the answers

What do the columns in an error matrix represent?

The reference data or the data that is known to be true or correct. (B) Signup and view all the answers

What is the purpose of an error matrix?

To calculate a variety of accuracy metrics. (B) Signup and view all the answers

In the example provided, how many reference sites were sampled in the field to verify the land cover type?

95 (B) Signup and view all the answers

What is the primary goal of stratified random sampling?

To ensure larger area classes receive more sampling points (B) Signup and view all the answers

What is the ideal way to collect reference data?

Conducting field collection, also known as ground-truthing (C) Signup and view all the answers

What is the advantage of using high-resolution reference imagery?

It is relatively inexpensive and generally faster than field collection (D) Signup and view all the answers

What is the purpose of using high-resolution remotely sensed data?

To assess the accuracy of low-resolution data (C) Signup and view all the answers

What is the benefit of using stratified random sampling in areas with varying class sizes?

It ensures that classes with a larger area receive more sampling points, while smaller area classes still have sampling points (D) Signup and view all the answers

What is the formula to calculate the overall accuracy?

Number of correctly classified sites / Total number of reference sites (B) Signup and view all the answers

What is the advantage of using field collection for collecting reference data?

It is the preferred method to obtain reference data (B) Signup and view all the answers

What is the relationship between error and accuracy?

Error + Accuracy = 100% (D) Signup and view all the answers

What type of error occurs when a reference site is left out from the correct class in the classified map?

Error of Omission (B) Signup and view all the answers

What is the term for the accuracy from the point of view of a map user?

User's Accuracy (A) Signup and view all the answers

How is the error of omission calculated?

By reviewing the reference sites for incorrect classifications (D) Signup and view all the answers

What is the term for the accuracy from the point of view of the mapmaker?

Producer's Accuracy (A) Signup and view all the answers

What is the Producer's Accuracy a measure of?

The number of correctly classified reference sites divided by the total number of reference sites (C) Signup and view all the answers

What is the relationship between the Producer's Accuracy and the Omission Error?

The Producer's Accuracy is the difference between 100% and the Omission Error (A) Signup and view all the answers

What does the User's Accuracy represent?

The reliability of the map from the user's point of view (A) Signup and view all the answers

How is the User's Accuracy calculated?

By taking the total number of correct classifications and dividing it by the row total (C) Signup and view all the answers

What is the Commission Error?

The number of incorrectly classified sites divided by the total number of classified sites (C) Signup and view all the answers

What is the relationship between the User's Accuracy and the Commission Error?

The User's Accuracy is the difference between 100% and the Commission Error (D) Signup and view all the answers