Remote Sensing from Air and Space

Remote sensing is a field of technology designed to enable people to look beyond the range of human vision. Whether it is over the horizon, beyond our limited human range, or in a spectral range outside human perception, we are in search of information. The focus here will be on imaging systems that extend our […]

Imagery Survey (Introduction to Remote Sensing) Part 1

To begin our study, we’ll take a look at some images that illustrate the range of data types found in remote sensing and show how what we can learn from remote sensing varies with spatial resolution and wavelength. The illustrations are chosen to suggest the variety of organizations involved with remote sensing—military and civil systems […]

Imagery Survey (Introduction to Remote Sensing) Part 2

IKONOS—San Diego/Coronado Island The launch of the IKONOS satellite in 1999 dramatically changed the world of remote sensing. For the first time, imagery comparable to that obtained from military systems was widely available to civilians. IKONOS offers 1-m-spatial-resolution panchromatic imagery, and 4-m-resolution multispectral (color) imagery. Shown in Fig. 1.17 is a color image of San […]

Three Axes (Introduction to Remote Sensing)

The sequence of images presented above has demonstrated the three dimensions associated with remote sensing imagery: the spatial, spectral, and temporal. Figure 1.25 illustrates these three dimensions, which are in general somewhat mutually exclusive. You can have high spatial resolution, but only at low temporal coverage (like Landsat: decent pictures, but only once every 16 […]

The Electromagnetic Spectrum (Remote Sensing)

We have discussed various remote sensing modalities and some characteristics of modern systems; at this point, it is necessary to review some basic physics. The chief thing to understand is the electromagnetic (EM) spectrum and EM radiation, of which light, radar, and radio waves are examples. We’ll look at the physical equations that underlie EM […]

Polarization of Radiation (Electromagnetic Basics) (Remote Sensing)

A subtle but important point is that E and B are both vectors. This vector character to EM radiation becomes important when we consider the concept of polarization. Familiar to most as an aspect of expensive sunglasses, polarization shows up in both optical observations and radar. A brief illustration of how EM waves propagate becomes […]

Energy in Electromagnetic Waves (Remote Sensing)

The wave theory of EM radiation (and light) explains a great deal about phenomena we observe in physics, but at the turn of the 20th century, it became obvious that a different perspective was needed to explain some of the interactions of light and matter—in particular, processes such as the photoelectric effect (and similar processes […]

Sources of Electromagnetic Radiation (Remote Sensing)

Now that we’ve defined electromagnetic waves and have an indication of how photons might be detected, let’s look at how EM waves are created. There are several major sources of electromagnetic radiation, all ultimately associated in some form with the acceleration (change of energy) of charged particles (mostly electrons). For remote sensing, these can be […]

Electromagnetic Radiation (EMR)-Matter Interactions (Remote Sensing)

EM radiation that impinges upon matter is called incident radiation. For the Earth, the strongest source of incident radiation is the sun. Such radiation is called insolation (a shortening of incoming solar radiation). The full moon is the next strongest source, but its radiant energy is only about a millionth that of the sun. Figure […]

The First Remote Sensing Satellite: Corona (Visible Imagery)

This topic discusses remote sensing in the visible EM spectrum, beginning with images and technology from the first remote sensing satellites (the Corona spy satellites) and concluding with a look at several optical imaging satellites, particularly the Hubble Space Telescope (HST). A little history Corona was America’s first operational space-reconnaissance project. It was developed as […]