Study Guide 4 (Lectures 15-17) PDF

Study Guides for Quiz 3 (Lectures 15-17) NOTE: Some knowledge points require the previous pages as important contexts to understand them. Please do NOT only read the marked pages. Lecture 15: What are the characteristics and types of neighborhood analysis (p8-9)? - Concept of moving wi...

Study Guides for Quiz 3 (Lectures 15-17) NOTE: Some knowledge points require the previous pages as important contexts to understand them. Please do NOT only read the marked pages. Lecture 15: What are the characteristics and types of neighborhood analysis (p8-9)? - Concept of moving window - Moving window is defined by its dimension (cells within window) - Output of operation associated with cell at center of the window - block : evaluates one set of cells and then moves to an entirely new set - Focal : moves one cell at a time to create overlapping neighborhoods What is zonal function (p12)? - Apply operations based on defined regions, or zones within an area - Defined areas of interest with unique ID for which we want to summarize data (total population in a country, etc) - Use zonal statistics tool What is terrain and terrain analysis (p17)? - Terrain = where water is flowing, lakes occur, land is affected by floods (influences soil mositure and food production) - Terrain analysis = analysis and interpretation of topographic features through GIS (slope, aspect, viewshed, elevation0 What are models for terrain (p18)? - Elevation contours: vector model - Digital elevation models (DEMs) - TIN (Triangular Irregular Network) - 3D point clouds, LiDAR  What are the typical US terrain data (p26)? - USGS - High resolution - NOAA/FEMA using LiDAR in coastal area What are DEM derivatives and how to calculate them in general (p31)? - Estimation of terrain attributes - Derived from the DEM through neighborhood or “moving window” analysis - Slope, aspect, curvature, flow direction What are slope and aspect (p33-35)? - Slope = change in elevation over horizontal distance (rise over run) - In percent or degrees - Aspect = directional measure in degrees of slope - Direction that topographic slope faces, direction water will flow What is flow direction, flow accumulation, and watershed (p40-42) - Flow direction = flows steepest downhill; direction is coded by facet number - Flow accumulation = for eachc cell in raster it counts the number of upstream cells that drain into the cell Lecture 16: What is aerial and satellite images and their advantage (p8-9)? - Aerial images = taken from aircraft - Satellite images = taken from satellites - Advantages: reliable info about physical objects and the environment without touching, large spatial coverage, long  term data records, cost-efficient - Images are taken as a snapshot of time - Both images can detect not visible to human eyes (infrared or long wavelength) What is reflection, absorption, and transmitted radiation (p10-11)? - Reflection = when electromagnetic radiation (light) strikes the surface and bounces off - Absorption = when material takes in the radiation, converting energy into internal energy (heat) - Transmitted radiation = passing of raduation through a material (not absorbed or reflected) What is wavelength and frequency (p13-14)? - Wavelength = the distance between maximums/minimums of a roughly periodic pattern - Frequency = number of wavelengths that pass a point per unit time What is irradiance, radiance, and reflectance (p16)? - Irradiance = radiation incident on a surface - Radiance = radiation coming from a surface and reaching the instrument - Reflectance = ratio between radiance (amt of light leaving a surface) to irradiance (amt of light stricking the surface) What is spectral signature and what is the characteristic of vegetation signature (p18-19)? - Spectral signature= each object has its own unique spectral response pattern - Characteristics of spectral signature of vegetation: - Red and blue - absorbed - Green - reflected - High reflectance in infrared (IR) spectrum  What is orthogonal aerial photography and what are the characteristics (p22-23)? - Orthogonal aerial = perpendicular to the ground - Removes the effects of the relief and camera tilt - Combines the image characteristics of the air photo with the georeferenced quality of a map - Ground features displayed in true position What are characteristics and common products of digital air photo imagery (p27) - Raster data without a value attribute table - Cell resolution [size of raster/pixel, pixel depth (number of colors)] - Used aerial imageries are aquired from vertical view Lecture 17 What are the four types of raster data resolution (p5-10)? - Spatial = size of the instantaneous field of view (ex: 10x10 m usually refers to pixel size) - Temporal = how often the sensor acquires data (ex: every 30 days, time interval between data acquisitions) - Radiometric = sensitivity of detectors to small differences in electromagnetic energy (the max number of brightness levels that the sensor can discriminate) - Spectral = number and width of spectral regions the sensor records data (ex: blue, green, red, near infrared thermal infrared, microwave) What is NDVI and how to interpret it (p15-16)? - NIR: Represents near-infrared reflectance and RED: red light reflectance - NDVI = (NIR-RED)/(NIR+RED) - Higher NVDI values (closer to 1) indicate denser vegetation, while lower values (closer to -1) represent less vegetation or non-vegetated areas - Emphsizes vegetation info while reducing other effects from atmosphere, staellite/sun geometry change - Cons - saturated at high biomass  What is false-color composite images and why do we apply false-color composition (p26)? - Different band combinations are displayed in R,G,B colors - Why? - to highlight different features of land surface like vegetation (enhance the contrast between the object of interest and background) What is hyperspectral imaging and how does it compare to multispectral imaging (p29-31)? - Hyperspectral data = sets are generally composed of hundreds of spectral bands of relatively narrow bandwidths (5-10nm) - While multispectral data sets are composed of 5 to 10 bands of relatively large bandwidths (70-400 nm) What are the two types of remote sensing sensors (p34-35)? - Passive sensors = uses energy from the sun - Active sensors = inputs its own energy source What is LiDAR? Is it passive sensor or active sensor (p36)? - Light Detection And Randing (LiDAR) = a similar technology to Radar, using laser light instead of radio waves - An active sensor with visible or near-infrared wavelength What is concept of “return”, and how to use it to get elevation data (p39-41)? - First Returns (first reflection): Used to determine the height of canopies (trees, vegetation, buildings). - Last Returns (final reflection): Used to filter data for ground surface elevation under vegetation canopies