Airborne videography as a classification and validation technique for Landsat TM-based vegetation mapping

Abstract

The Oregon Department of Fish and Wildlife's (ODFW) Ecological Analysis Center (EAC) is in the process of creating, from Landsat Thematic Mapper (TM) imagery, a vegetation map of Oregon that will meet the latest standards set by the National Gap Analysis Program. Since field verification is often expensive and by nature intensive, ODFW wanted to determine the feasibility of using airborne videography to help classify and validate their Oregon vegetation map. In 1993, ODFW sampled approximately 4% of Oregon with airborne videography by flying north-south transects at 30-km intervals to be used for these purposes. This research was designed to examine how and to what extent airborne videography can be used for assessing the accuracy of classified satellite imagery in vegetation mapping. An accuracy assessment strategy incorporating the ODFW airborne videography was developed and tested on a pilot study area consisting of the Luckiamute and Rickreall watersheds in western Oregon. Airborne videography was found to have more potential as a classification aid than as an accuracy assessment tool. Its limited usefulness in accuracy assessment results primarily from the necessity to field verify any interpretation made of the videography before it can be successfully incorporated into an accuracy. assessment methodology. Additionally, the difficulty of obtaining a sufficient sample for all vegetation classes and the relatively poor spatial and spectral resolution of current airborne video systems impede its use in accuracy assessment. A field verification process combining global positioning system (GPS) and geographic information system (GIS) technologies with a laptop computer is outlined as a more efficient and accurate alternative to using the ODFW airborne videography for accuracy assessment of the Oregon vegetation map.