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AERIAL IMAGERY <br /> GLOSSARY <br /> Six Common Imagery Terms - Explained <br /> SPATIAL RESOLUTION <br /> The smallest spatial element discernible on the image <br /> captured -often represented in units of inches or <br /> centimeters.GSD(Ground Sample Distance)expresses the <br /> physical distance between pixel centers of a given aerial <br /> imagery product. <br /> © POSITIONAL ACCURACY <br /> • A measure of how well the imagery aligns to the real world - a <br /> process known as Georeferencing. Use of ground control points <br /> and post-processing improve accuracy,with error typically <br /> expressed as RMSE (Root Mean Square Error). <br /> © REFRESH RATE <br /> Also known as temporal resolution, a refresh rate (or revisit <br /> rate)indicates how often a particular area is re-captured <br /> and reprocessed. Higher refresh rates allow for more up-to- <br /> date imagery and allow for processes such as change <br /> detection. <br /> OSPECTRAL BANDS <br /> Spectral Resolution refers to the number and width of <br /> wavelengths captured by the imagery sensor.While the human <br /> eye can see in R-G-B (Red, Blue,Green),the capture of additional <br /> wavelengths such as(near)infrared,allows for enhanced analysis <br /> of agriculture and forestry. Products containing a wide range of <br /> bands are referred to as multispectral imagery. <br /> © NADIR / OFF-NADIR <br /> The angle of the sensor relative to the capture platform. On- <br /> Nadir imagery(O to 3 degrees) is considered "straight down" or <br /> vertical.whereas Off-Nadir indicates oblique imagery(often <br /> captured at 45 degrees).Satellite sourced imagery may be <br /> captured at a variety of angles. <br /> OBIT-DEPTH <br /> Information stored for each pixel is captured and rendered at <br /> a particular bit-level.This dictates the number of potential <br /> values (for example,discrete colors)any given cell may <br /> represent.8-Bit indicates 256 possible values for each R-G-B. <br /> 40 Higher bit-depths include 16-bit and 32-bit for increased <br /> levels of color detail and dynamic range. G <br /> APPLIED • @2020 <br />