30 Questions
What does accuracy refer to in the context of remote sensing?
The proportion of agreement between a classified map and the reference data
What type of accuracy refers to how well the class name on the map corresponds to what is really on the ground?
Thematic Accuracy
What is the term for the data collected in the field to assess accuracy?
Ground-Truth Data
What is the relationship between accuracy and precision?
There is an inverse relationship between them
What is spatial accuracy related to?
The spatial resolution of the data set
What is an example of a map with high thematic precision?
A map distinguishing Lodgepole pine, Douglas fir, Ponderosa
What is a potential drawback of using reference data in geospatial analysis?
It may not accurately represent the actual conditions on the ground.
What is the purpose of comparing the classified data to the reference data?
To determine the accuracy of the classification.
What type of array is used to create an error matrix?
An (n x n) array.
What do the columns in an error matrix represent?
The reference data or the data that is known to be true or correct.
What is the purpose of an error matrix?
To calculate a variety of accuracy metrics.
In the example provided, how many reference sites were sampled in the field to verify the land cover type?
95
What is the primary goal of stratified random sampling?
To ensure larger area classes receive more sampling points
What is the ideal way to collect reference data?
Conducting field collection, also known as ground-truthing
What is the advantage of using high-resolution reference imagery?
It is relatively inexpensive and generally faster than field collection
What is the purpose of using high-resolution remotely sensed data?
To assess the accuracy of low-resolution data
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
What is the formula to calculate the overall accuracy?
Number of correctly classified sites / Total number of reference sites
What is the advantage of using field collection for collecting reference data?
It is the preferred method to obtain reference data
What is the relationship between error and accuracy?
Error + Accuracy = 100%
What type of error occurs when a reference site is left out from the correct class in the classified map?
Error of Omission
What is the term for the accuracy from the point of view of a map user?
User's Accuracy
How is the error of omission calculated?
By reviewing the reference sites for incorrect classifications
What is the term for the accuracy from the point of view of the mapmaker?
Producer's Accuracy
What is the Producer's Accuracy a measure of?
The number of correctly classified reference sites divided by the total number of reference sites
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
What does the User's Accuracy represent?
The reliability of the map from the user's point of view
How is the User's Accuracy calculated?
By taking the total number of correct classifications and dividing it by the row total
What is the Commission Error?
The number of incorrectly classified sites divided by the total number of classified sites
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
Understand the concept of accuracy in remote sensing and its importance in measuring the true value of classified data. Learn about map accuracy and its relation to ground-truth data.
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