Hyperspectral Remote Sensing of Habitat Heterogeneity Between Tide-Restricted and Tide-Open Areas in the New Jersey Meadowlands

Glossary

Accuracy assessment

Accuracy assessment in remote sensing refers to the comparison of a classification to a geographical image that is assumed to be true. Usually, the assumed-true data are derived from field observations.

Class-level metrics

A set of metrics used in landscape ecology to measure the aggregate properties of the landscape patches belonging to a single class or patch type (see below).

Downwelling radiance

See upwelling and downwelling radiance, below.

Dredge spoils

The sediment removed from a body of water during dredging.

Edge effects

Altered environmental and biological conditions at the edge of fragmented habitat.

Georeference

Also referred to as registering, this is the establishment of the relationship between page coordinates (i.e., x, y) of a planar map of an image with known real-world coordinates (i.e., longitude, latitude, etc.).

Heterogeneity

The quality or state of being heterogeneous, or consisting of dissimilar elements or parts.

Histogram matching

An equalization technique often used to correct the brightness difference among flight lines (images) captured at different times of the day.

Hyperspectral remote sensing

Also known as imaging spectroscopy, this relatively new technology can simultaneously acquire images of the earth's surface in many narrow, contiguous, spectral bands.

Irregular polygon

Any shape or figure on a plane that has many straight sides of no regular length.

Landscape-level metrics

Metrics used in landscape ecology to measure the aggregate properties of an entire mosaic of landscape patches.

Landscape Metrics Algorithms that quantify specific spatial characteristics of landscape patches, classes of these patches, or entire landscape mosaics. They include landscape-level and class-level metrics (see above).

Microinvertebrate

An animal without a backbone that is too small to be seen with the naked eye.

Minimum Noise Fraction (MNF) rotation

A method used to separate hyperspectral image noise from signals and compress spectral information of the image into a few informative bands.

Mosaic

An assemblage of overlapping aerial or space photographs or images whose edges have been matched to form a continuous pictorial representation of a portion of the earth's surface.

Nanometer (nm)

10⁹ meters, or one billionth of a meter. It is commonly used in measuring the wavelengths of visible light (400 nm to 700 nm).

North American Datum 83

A commonly used geographic coordinate system based on ground and satellite data.

Orthophoto

A photograph derived from a conventional-perspective photograph by simple or differential rectification so that image displacements caused by camera tilt and relief of terrain are removed.

p < 0.05

An indicator of statistical significance in which the probability of the result of a study's being a chance occurrence is less than 5 in 100.

Panne (or salt panne)

A small pond or pool in a marsh that usually holds water as the tide recedes.

Patch types

Discrete areas of landscape with relatively homogeneous surface composition and environmental conditions.

Pixel

A two-dimensional picture element that is the smallest nondivisible element of a digital image.

Q-Q plot (quantile-quantile plot)

A graphing technique for determining if two sets of data come from populations with the same distribution.

Radiance

A measure of the energy radiated by the object together with the frequency distribution of that radiation.

Reflectance

The fraction of radiant energy that is reflected from a surface.

Shannon Diversity Index

An algorithm for quantifying the diversity of a landscape based on two components: the number of different patch types and the proportional distribution of area among these patch types.

Spectrum (pl. spectra)

The distribution of energy emitted by a radiant source arranged in order of wavelengths.

Subset

The process of clipping an image into the area of interest.

Upwelling and downwelling radiance

Upwelling radiance is the amount of electromagnetic radiation reflected upward from the ground's surface. It includes downwelling radiance, which is the thermal energy radiated onto the ground by all objects in a hemisphere surrounding it, including topography and atmospheric gases and aerosols. To obtain an atmospherically corrected reflectance, downwelling radiance must be subtracted from upwelling radiance.

White reference panel

A standard reference panel made of a special white material and used to fix the maximum reflectance value for each sampling period. This way measurements made at different dates can be compared regardless of the slight changes in illumination that may occur from one day to another.