Color infrared orthoimagery is an excellent technology for studying vegetation and other aspects of the natural and human environment.
According to
Wikipedia: Infrared:
Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light (400-700 nm), but shorter than that of terahertz radiation (100 µm - 1 mm) and microwaves (~30,000 µm). Infrared radiation spans roughly three orders of magnitude (750 nm and 100 µm).
Infrared imaging is used extensively for both military and civilian purposes. Military applications include target acquisition, surveillance, night vision, homing and tracking. Non-military uses include thermal efficiency analysis, remote temperature sensing, short-ranged wireless communication, spectroscopy, and weather forecasting. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space, such as molecular clouds; detect cool objects such as planets, and to view highly red-shifted objects from the early days of the universe.
Humans at normal body temperature radiate chiefly at wavelengths around 10μm (micrometers).
At the atomic level, infrared energy elicits vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared energy range, based on their frequency and intensity.
1994 infrared photo of the Mississippi River between Minneapolis and Saint Paul.
* North is up.
* Dark red is vegetation while bluish-green is roads, asphalt, and buildings.
* The Ford Parkway Bridge crosses the river just north of Lock and Dam No. 1, between the Ford Twin Cities Assembly Plant on the right, and Minnehaha Park on the left.
* A pooled Minnehaha Creek is the narrow dark curved shape in the upper left, becoming narrower as it crosses Highway 55 eastward into the tree-covered park.
* Minnehaha Falls is one-fourth of the way along a line between the creek's entrance to the park, to Lock and Dam 1. A light blue area is a parking lot and observation area which is just east (right) of the falls.
* The bridge southeast of the falls which crosses the Minnehaha Creek ravine provided access to the Veterans Home area, and has since been closed.
Source of photo and caption:
Wikipedia: Infrared photographyAccording to
Grand River Conservationa Authority: Orthoimagery:
Orthoimagery combines the image characteristics of an aerial photograph with the geometric qualities of a map. Unlike a normal aerial photograph, distortion and relief displacement is removed so ground features are displayed in their true planimetrically correct position. Orthoimagery supports making direct measurements of locations, distances, angles, directions, and areas while offering a realistic visualisation of the landscape.
Acording to
Wikipedia: Infrared photography:
Color infrared transparency films have three sensitized layers that, because of the way the dyes are coupled to these layers, reproduce infrared as red, red as green, and green as blue. All three layers are sensitive to blue so the film must be used with a -blue (i.e., yellow) filter. The health of foliage can be determined from the relative strengths of green and infrared light reflected; this shows in color infrared as a shift from red (healthy) towards magenta (unhealthy).
The attached KMZ file contains an index to the tiles of color infrared orthoimagery available for Suffolk County, New York for 2007 from the
New York State Geographic Information Systems Clearinghouse. The tiles are available in jp2 format, and must be converted to jpg or another appropriate format to be used in Google Earth. The KMZ attachment also contains two sample color infrared images for the
Stony Brook Southampton campus area as overlays.
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