Thematic and positional accuracy assessment of digital remotely sensed data

Accuracy assessment or validation has become a standard component of any land cover or vegetation map derived from remotely sensed data. Knowing the accuracy of the map is vital to any decisionmaking performed using that map. The process of assessing the map accuracy is time consuming and expensive. It is very important that the procedure be well thought out and carefully planned to be as efficient as possible. This paper presents a brief review of the current methods used in thematic map accuracy assessment. A discussion of positional error is included as it is impossible to assess thematic accuracy without carefully considering positional accuracy.