Remote sensing (RS) of Earth's environment using airborne and satellite-borne sensors has greatly improved our ability to describe and measure the characteristics of Earth's atmosphere, oceans, land surfaces, and dynamic processes over time and space. Products derived through remote sensing enhance our geographical understanding of the environment and how humans interact with and/or affect the environment. Ground reference data (GRD) are critical to the creation of accurate and useful RS products. GRD provide information about actual conditions of features or phenomena of interest and are used for calibration and validation purposes.

GRD may be in the form of point-based information, plot samples, or maps with areal units (e.g., polygons) having thematic or continuous data. Before GRD are collected, the exact type and nature of the GRD ...