Small pixel sizes, such as 3 inch or 10 centimeter, result in very large files that can be difficult to process, store, and manage. Generally, the smaller the pixel size, the greater the detail contained in the image. GSD determines the level of spatial detail and types of features visible in the image. This is a function of both the sensor capability and the flying height of the sensor. Spatial resolution refers to the size of the pixels (picture elements) on the ground comprising the image, and is often referred to as ground sample distance (GSD). The nature of the information contained in imagery depends primarily on three types of resolution: spatial, spectral, and temporal, which all affect the minimum mapping unit of a project. Whether imagery is being visually analyzed or processed using remote-sensing image processing techniques, factors such as minimum mapping unit, spectral band width and placement, and geopositional accuracy, determine the suitability of particular types of imagery for your project’s goals and requirements. The first level of distinction is the information content contained in imagery, and the geometric characteristics of imagery.
The conditions of each project drive the imagery collection and processing requirements, which distinguish types of imagery into categories. All remote-sensing imagery is not the same, and it is generally collected to meet project requirements. Remote-sensing imagery is collected by a satellite, an aircraft, or a drone platform.