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Imagery is collected by remote sensing systems managed by either public or private organizations. It is characterized by a complex set of variables, including

 collection characteristics: image spectral, radiometric, and spatial resolutions, viewing angle, temporal resolution, and extent; and

 organizational characteristics: image price and licensing and accessibility.

The choice of which imagery to use in a project will be determined by matching the project’s requirements, budget, and schedule to the characteristics of available imagery. Making this choice requires understanding what factors influence image characteristics. This chapter provides the fundamentals of imagery by first introducing the components and features of remote sensing systems, and then showing how they combine to influence imagery collection characteristics. The chapter ends with a review of the organizational factors that also characterize imagery. The focus of this chapter is to provide an understanding of imagery that will allow the reader to 1) rigorously evaluate different types of imagery within the context of any geospatial application, and 2) derive the most value from the imagery chosen.