Accuracy assessment and validation of remotely sensed and other spatial information

Today, validation or accuracy assessment is an integral component of most m apping projects incorporating remotely sensed data. Other spatial informati on may not be so stringently evaluated, but at least requires meta-data tha t documents how the information was generated. This emphasis on data qualit y was not always the case. In the 1970s only a few brave scientists and res earchers dared ask the question, 'How good is this map derived from Landsat MSS imagery?' In the 1980s, the use of the error matrix became a common to ol for representing the accuracy of individual map categories. By the 1990s , most maps derived from remotely sensed imagery were required to meet some minimum accuracy standard. A similar progression can be outlined for other spatial information. However, this progression is about 5 years behind the validation of remotely sensed data. This paper presents a series of steps moving towards better assessment and validation of spatial information and asks the reader to evaluate where they are in this series and to move for-w ard.