EnvirSt 371 Midterm Exam (copy)

Remote Sensing

The science of deriving information about the Earth from satellite images and aerial photographs.

Aerial Photographs

Photographs taken from an airborne perspective, such as from a kite, plane, or balloon.

Aerial Photography

The field concerned with taking aerial photographs.

Image Interpretation

Deriving information from images using visual elements.

Satellite Imagery

Photos from orbiting satellites that cover large areas of Earth’s surface in multiple spectra.

Landsat

First earth-orbit satellite designed for observing land.

Multispectral Scanner System (MSS)

Became the primary sensor for Landsat 1 after its primary sensor failed.

UAV

Unmanned aerial vehicles.

Photo-Interpretation

The field of analyzing photographs to derive information.

Photogrammetry

The practice of making accurate measurements from photographs.

Neighborhood Scale

High resolution, 4m pixels, detailed but small footprint.

City Scale

Medium resolution, 30m pixels.

Regional/Global Scale

Coarse resolution, 500-1000m pixels, loss of detail but large footprints.

Foundation of Remote Sensing

The partnership of aerial photography with the airplane.

Military Applications

Drove rapid development of aerial photography during WW1 and WWII.

EM Spectrum

Consists of an electrical field and a magnetic field at right angles to each other.

Wavelength

Distance from one wave crest to the next.

Frequency

The number of crests passing a fixed point in a given period of time.

Amplitude

The height of each peak in a wave.

Particle Theory

Describes energy as a stream of particles (photons) moving in a straight line.

Active Remote Sensing

Detects radiation reflected by objects due to artificially generated energy sources.

Passive Remote Sensing

Detects naturally reflected radiation from objects.

Radiation

Transfer of energy in the form of electromagnetic waves or particles.

Conduction

Transfer of kinetic energy to another body through collision.

Convection

Transfer of energy by circulation through gas or liquid.

Photons

Quantums of light, tiny units of light energy.

Quanta

The smallest unit of energy.

Thermal Infrared (IR)

Conveys temperature information.

Water Absorption

Highest at specific dips on the spectrum where vegetation is concerned.

Atmospheric Transmittance

Amount of radiation that reaches the Earth's surface.

Refraction

Incoming radiation is bent as it travels through different atmospheric layers.

Scattering

EM energy is redirected by atmospheric constituents.

Rayleigh Scattering

Occurs with very small particles, affects shorter wavelengths more.

Mie Scattering

Occurs with particles comparable in size to the wavelength.

Transmittance

The ability to transmit energy through materials.

Albedo

Reflectance of surfaces.

Leaf Area Index (LAI)

Ratio of leaf area to ground area.

Chlorophyll

The green pigment in plants that absorbs light for photosynthesis.

Photosynthesis

Process by which plants synthesize carbohydrates from CO2 and H2O using light.

Fluorescence

Emission of radiation at one wavelength after illumination at another.

Canopy

The upper layer of leaves formed by the tops of trees.

Spectral Vegetation Curve

Describes vegetation reflectance in relation to wavelengths.

NDVI

Normalized Difference Vegetation Index, a vegetation index used to assess plant health.

Kauth-Thomas Tasseled Cap Transform

A transformation for analyzing variations in reflectance in images.

Classification

Assigns labels to pixels based on their characteristics.

Supervised Classification

Involves training samples to guide the classification process.

Unsupervised Classification

Aggregates data into clusters without pre-defined categories.

Spatial Resolution

Measure of the smallest separation of two identifiable objects.

Pixel

The smallest unit of an image that can be represented digitally.

Binary Data

Data represented using two symbols, 0 and 1.

Data Compression

Reduces data size by eliminating redundancies.

Geometric Correction

Aligns images to a map or coordinate grid.

Radiometric Correction

Corrects for distortions due to sensor noise or atmospheric effects.

Histogram Equalization

Enhances contrast by distributing pixel values more evenly.

Bit Depth

Refers to the number of bits used to represent the color of a single pixel.

Instantaneous Field of View (IFOV)

The ground area covered by a sensor's view angle.

Multitemporal Imagery

More than three images captured over time.

Hyperspectral Imagery

Imaging that captures dozens to hundreds of bands for detailed analysis.

Signal to Noise Ratio

Measure of the desired signal's strength to the background noise.

Television Operator

Records and transmits readings from a measuring device.

Urban Planning Applications

Surveying land and monitoring human population dynamics.

Agricultural Monitoring Applications

Tracking crop health and maturity and assessing land use.

Soil Reflectance Factors

Controlled by moisture content, organic matter, and soil texture.

Natural Color (True Color)

Image representation with red, green, and blue bands as perceived by the human eye.

Color Infrared (False-Color)

Use of NIR, red, and green bands for enhanced observation of vegetation.

Additive Color Theory

Mixing light from different wavelengths produces new colors.

Subtractive Color Theory

Mixing pigments absorbs certain wavelengths and reflects others.

Image Interpretation Keys

Reference materials designed for rapid identification of aerial image features.

Stereoscopy

Deriving distance information from overlapping images.

Orthophoto

Aerial photograph corrected for distortion.

Ground Nadir

Point directly below the center of the camera lens.

Overlap in Aerial Photographs

Typically 60% overlap in the direction of flight.

Photographic Nadir

Intersection of the ground nadir and lens center.

Mission Planning

Evaluating and assigning points and flight paths for drone operation.

Representative Fraction

Scale ratio between map size and actual size.

Georectification

Aligning images to spatial references for accuracy.

Orthoretification

Correcting aerial images to remove tilt and relief displacement.

Statistics in Remote Sensing

Analytical data regarding image pixel values.

Digital Number (DN)

Value assigned to pixels in a digital image.

Image Stretching Techniques

Used to enhance contrast and clarity in images.

Masking in Remote Sensing

Removing unwanted areas from an image for clear analysis.

Image Transforms

Mathematical operations applied to bands for feature enhancement.

Health Indicators in Vegetation

Photosynthetic efficiency, chlorophyll content indicating plant stress.

Displacement in Aerial Images

Objects appearing displaced due to perspective differences.

Terrain Influence on Remote Sensing

Altitude, slope, and vegetation can affect data capture.

Radiative Transfer

Process of energy transfer within the atmosphere.

Atmospheric Constituents

Gases and particles that affect remote sensing measurements.

Cloud Cover Impact

Obscures view and affects data accuracy.

High Spatial Resolution

Allows for detailed analysis but typically represents less area.

Low Altitude Flying

Provides high detail but introduces more atmospheric influences.

Drone Applications

Used for precise mapping and surveillance.

Aerial Survey Missions

Planned photography flights to gather visual data.

Crop Monitoring Technologies

Utilizes multispectral sensors for assessing health and maturity.

Urban Growth Tracking

Observing changes in land use over time.

Disaster Management Imaging

Utilizes remote sensing to assess damage in areas post-disaster.

Environmental Monitoring Applications

Forest conservation and biodiversity assessments using imagery.

Sub-pixel Analysis

Investigating mixed pixels to better understand ground cover.

Temporal Analysis

Comparative image evaluation over periods to track changes.

Spectral Signature Analysis

Characterizing surfaces based on reflectivity across wavelengths.

Fiducial Marks

Index marks on aerial photographs for orientation.