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Dark current The apparent signal of an instrument (e.g., spectrometer) in the
absence of any external stimulus (e.g., light). Typically, dark current is a function
of temperature and must be subtracted from the desired signal to yield the true
value of the external signal.
Dark subtraction The subtraction of the dark current values to yield the true
external signal detected; typically done for spectra or images.
Data augmentation Image transformations that improve machine learning performance for image classification by using the data available to create additional data.
Data dimensionality The number of orthogonal (independent) dimensions (attributes) in a dataset, e.g., defined by principal components analysis, singular value
decomposition, or discriminant analysis.
Data latency The time it takes for an end user to retrieve source data from a data
collection such as a field campaign, flight campaign, or orbital overpass.
Deciduous Shedding leaves, so that in part of the year the plant lacks leaves.
Contrast with evergreen. Many high latitude oak trees shed leaves in the autumn
and are thus deciduous, but in lower latitudes some keep leaves all year and so
are evergreen.
Decomposition An important process in nutrient cycling by which plant and
animal litter, detritus, and other organic substances are broken down into more
simple organic or mineral forms.
Decomposition analysis in the context of processing radar data, the separation of
polarimetric radar backscatter into components representing different scattering
mechanisms, such as volume scattering, surface scattering, and double bounce
reflection.
Dehiscence Splitting along a built-in line of weakness in plant structure in order
to release its contents, such as in the rupture of seed capsules for the release and
dispersal of seeds.
Demography The study of births, deaths, incidence of disease, etc., to understand
the changing structure, distribution, and size of populations.
Diameter at breast height (DBH) Tree stem diameter at breast height, approximately 1.3 m above the ground; a common measurement in forest inventories.
Diatoms Single-celled algae (or phytoplankton) in the class Bacillariophyceae
with cell walls composed of silica. They are found in oceans, freshwater bodies,
and soils and considered to be one of the most diverse and ecologically important
groups of phytoplankton. Globally, there are an estimated 20,000 to 2 million
species of diatoms.
Dicot Short for dicotyledon. These are the type of flowering plants (angiosperms)
that have two cotyledons (seed leaves) at germination.
Diffuse light Radiation scattered from a surface in all directions. A surface that
scatters perfectly in all directions is termed a Lambertian (isotropic) surface.
Contrast to anisotropic.
Digital surface model (DSM) A gridded dataset containing the absolute elevations including natural and built features of the Earth’s surface.
Glossary
Dark current The apparent signal of an instrument (e.g., spectrometer) in the
absence of any external stimulus (e.g., light). Typically, dark current is a function
of temperature and must be subtracted from the desired signal to yield the true
value of the external signal.
Dark subtraction The subtraction of the dark current values to yield the true
external signal detected; typically done for spectra or images.
Data augmentation Image transformations that improve machine learning performance for image classification by using the data available to create additional data.
Data dimensionality The number of orthogonal (independent) dimensions (attributes) in a dataset, e.g., defined by principal components analysis, singular value
decomposition, or discriminant analysis.
Data latency The time it takes for an end user to retrieve source data from a data
collection such as a field campaign, flight campaign, or orbital overpass.
Deciduous Shedding leaves, so that in part of the year the plant lacks leaves.
Contrast with evergreen. Many high latitude oak trees shed leaves in the autumn
and are thus deciduous, but in lower latitudes some keep leaves all year and so
are evergreen.
Decomposition An important process in nutrient cycling by which plant and
animal litter, detritus, and other organic substances are broken down into more
simple organic or mineral forms.
Decomposition analysis in the context of processing radar data, the separation of
polarimetric radar backscatter into components representing different scattering
mechanisms, such as volume scattering, surface scattering, and double bounce
reflection.
Dehiscence Splitting along a built-in line of weakness in plant structure in order
to release its contents, such as in the rupture of seed capsules for the release and
dispersal of seeds.
Demography The study of births, deaths, incidence of disease, etc., to understand
the changing structure, distribution, and size of populations.
Diameter at breast height (DBH) Tree stem diameter at breast height, approximately 1.3 m above the ground; a common measurement in forest inventories.
Diatoms Single-celled algae (or phytoplankton) in the class Bacillariophyceae
with cell walls composed of silica. They are found in oceans, freshwater bodies,
and soils and considered to be one of the most diverse and ecologically important
groups of phytoplankton. Globally, there are an estimated 20,000 to 2 million
species of diatoms.
Dicot Short for dicotyledon. These are the type of flowering plants (angiosperms)
that have two cotyledons (seed leaves) at germination.
Diffuse light Radiation scattered from a surface in all directions. A surface that
scatters perfectly in all directions is termed a Lambertian (isotropic) surface.
Contrast to anisotropic.
Digital surface model (DSM) A gridded dataset containing the absolute elevations including natural and built features of the Earth’s surface.
Glossary