RS Mega

remote sensing

The acquisition of information about the state/condition of an object through sensors that are not physically in contact with it

satellite remote sensing

assisting search and rescue operations, mapping the earth's surface, assessing flood damage

applications of remote sensing

Agriculture, forestry, emergency management, lclu mapping

components of remote sensing system

energy source, recieving system, end users

geostationary orbit

An orbit in which a satellite orbits Earth at the same rate as Earth rotates and thus stays over the same place all the time.

polar orbit

orbit that moves over Earth's north and south poles as Earth rotates underneath

passive sensors

remote sensing systems which measure energy that is naturally available

active sensors

provide their own energy source for illumination

electromagnetic spectrum

All of the frequencies or wavelengths of electromagnetic radiation

Wavelength

Horizontal distance between the crests or between the troughs of two adjacent waves

Frequency

the number of complete wavelengths that pass a point in a given time

Amplitude

Height of a wave

emission

the production and discharge of something, especially gas or radiation

Stefan-Boltzmann Law

The relationship stating that an object emits energy at a rate proportional to the fourth power of its temperature, in Kelvins.

Wien's Displacement Law

The wavelength of peak emission from a black body is inversely proportional to the absolute (kelvin) temperature of the body.

Absorption

energy goes into an object

Reflection

The bouncing back of a wave when it hits a surface through which it cannot pass.

Greyscale

a range of gray shades from white to black, as used in a monochrome display or printout

true color composite

an image arranged by placing the red band in the red color gun, the green band in the green color gun, and the blue band in the blue color gun

false color composite

an image arranged when the distribution of bands differs from placing the red band in the red color gun, the green band in the green color gun, and the blue band in the blue color gun

Transmisson

the passage of light through an object

Scattering

reflection of light in all directions

atmospheric window

A wavelength band in which our atmosphere absorbs little radiation

rayliegh scattering

When particles are very small (less than 20 nm), they will cause visible light to be scattered differently based on the wavelength (color).

Mie Scattering

scattering of light caused by atmospheric particles the same size as the wavelength being scattered

nonselective scattering

scattering of light caused by atmospheric particles larger than the wavelength being scattered

reflectance

The percentage of light reflected from a surface.

solar irradiance

The rate of energy received

from the sun.

Radiation

Energy that is radiated or transmitted in the form of rays or waves or particles.

Earth-observing satellites

i.e. landsat

remote sensing process

-Statement of the problem

-Data Collection

-Data to Information Conversion

-Information Presentation

wavelength and frequency are

inversely proportional

specular reflection

a reflection produced by a smooth surface in which parallel light rays are reflected in parallel

diffuse reflection

Reflection that occurs when parallel rays of light hit a rough surface and all reflect at different angles

reflection

r/i

Albedo

Ability of a surface to reflect light

spectral albedo

m/e

Planck's Law

a relationship between the energy carried by a photon and its wavelength

DN values

digital number/pixel

ascending pass

satellite go up

descending pass

satellite go down

revisit period

how long it takes a satellite to go to the same spot

Satellite Swath

area that is imaged

nadir point

the point directly below the aircraft, usually near the center of an aerial image

Orbit Cycle

Satellite passes same spot at set time in same light conditions

spatial resolution

A term that refers to how small the elements of an image are; high spatial resolution means the device or technique can resolve very small elements; in neuroscience it describes how small of a structure in the brain can be imaged.

spectral resolution

the bands and wavelengths measured by a sensor

multispectral sensor

a sensor that can measure multiple wavelength bands simultaneously

hyperspectral sensor

a sensor that can measure hundreds of different wavelength bands simultaneously

Instantaneous Field of View (IFOV)

-What the sensor (detector) sees as it passes over a target

-Ground segment sensed by IFOV referred to as the ground resolution element

-Nominal diameter of ground resolution element determines system's spatial resolution

radiometric resolution

the degree of a sensor's ability to determine fine differences in a band of energy measurements

temporal resolution

A term that refers to how small a unit of time can be measured; high temporal resolution means capable of resolving very small units of time; in neuroscience it describes how precisely in time a process can be measured in the brain.

multispectral scanner

across-track scanning

a scanning method using a rotating mirror to collect data by moving the device back and forth across the width of the satellite's swath

along-track scanning

a scanning method using a linear array to collect data directly on a satellite's path

spectral signature

a unique identifier for a particular item, generated by charting the percentage of reflected energy per wavelength against a value for that wavelength

Resolution of an image

density of pixels used to represent the image

radiometric correction

corrects distortion of digital images to improve the fidelity of brightness values, differentiates real changes vs noise. Methods include math models but certain parameters known (e.g. atmostpheric conditions) or observation to unchanging reference targets whose radiometry is known.

geometric correction

Image-processing procedure that corrects spatial distortions in an image.

geometric correction

Image-processing procedure that corrects spatial distortions in an image.

systematic distortion

Geometric irregularities on images that are caused by known and predictable characteristics.

non systematic distortion

distortion in the image that is caused by the sensor's circumstances varying in unpredictable ways

no one equation to correct for it

often corrected for pixel-by-pixel

relief displacement

the effect seen in aerial imagery where tall items appear to "bend" outward from the photo's center toward the edges

Georegistration

Also known as georeferencing - how good is the fit

RMSE

root mean square error

radiometric correction

corrects distortion of digital images to improve the fidelity of brightness values, differentiates real changes vs noise. Methods include math models but certain parameters known (e.g. atmostpheric conditions) or observation to unchanging reference targets whose radiometry is known.

reflectance

The percentage of light reflected from a surface.

nearest neighbor

most basic method of interpolation; duplicates the nearest pixel

bilinear interpolation

A resampling method that uses the distance-weighted average of the four nearest pixel values to estimate a new pixel value

cubic convolution

A resampling method that uses the distance-weighted average of the 16 nearest pixel values to estimate a new pixel value

DN value

Digital Number

absolute radiometric correction

extracts absolute reflectance of scene objects at the earth's surface, requires atmospheric properties and sensor calibration, a challenge to acquire.

relative radiometric correction

reduces atmospheric and other variation among multiple images by adjusting the radiometric properties of target images to match a base image (Hall et al 1991).

Dark Object Subtraction

Look for an object in the scene that is dark (preferably deep water), and assume that ANY reflectance coming from that object is from atmospheric processes. We then CORRECT the rest of the image for this amount of reflectance.

reflectance equation

radiance/incident radiation

radiance at sensor

radiant object + path radiation

chavez cos(T)

similar parameters to DOS but add atmos gas abs and rayliegh scatt correction in all bands

histogram matching

the transformation of an image so that its histogram matches a specified histogram.

destriping

application of algorithms to adjust incorrect brightness values to values thought to be near the correct value

Image histogram

An interactive graph that can be used to adjust the colors in a digital photo.

spatial filtering

done to emphasize or deemphasize certain features depending on the spatial frequency

Intensity

Intensity represents the brightness of the pixel.

Hue

Hue is the dominant wavelength (dominant color)

Normalization Formula

(Ba- Bb)/(Ba+Bb)

Ba = higher value/end for what you are measuring

Bb = lower value/end for what you are measuring

Indices

index of values with specific meaning made by combining two or more bands to create an image that shows new informatio.

spectral ratios

Two spectral bands combined, simplest image transformation

Saturation

Saturation refers to the color purity (combination with other tones)

HLS stands for

hue, saturation, lightness/luminance

Pansharpening

FCC + Panchromatic band = FCC w/ Panchromatic band

Image transformations

manipulation of multiple bands of data, whether from a single multispectral image or from two or more images of the same area acquired at different times