Fundamentals of RS and GIS Exam

Final flashcard set

What is the First Law of Geography according to Waldo Tobler?

Everything is related to everything else, but near things are more related than distant things.

What is vector data in spatial analysis?

Vector data consists of points, lines, and polygons that represent spatial features and their attributes.

What does buffering refer to in basic geometry processing?

Buffering creates an area around a feature, such as a 100 m buffer around a proposed railway route, to show the affected area.

What does the term 'Overlay Tools' include in spatial analysis?

Overlay Tools include functions like Intersection, Union, Dual, and Difference to analyze added layers of data.

What is the purpose of the Dissolve function in spatial analysis?

To aggregate or sum features based on a common attribute, such as summing malaria cases per country.

What does Join mean in the context of spatial data processing?

Joining merges two attribute tables based on a shared attribute, allowing spatial analysis with non-spatial data.

What is Zonal Statistics used for in spatial analysis?

To summarize the values of a raster dataset within the defined zones of another dataset.

What key questions does point pattern analysis try to answer?

It investigates if spatial points are related to neighborhood occurrences, such as crime or disease hotspots.

What is kernel density estimation (KDE)?

KDE is a technique used to determine density patterns of points by summarizing cases over a moving window.

How does Ripley’s K-function help in spatial analysis?

It determines the expected number of points within a certain distance to assess spatial clustering, dispersion, or randomness.

What is the significance of Moran’s measure of spatial autocorrelation?

It evaluates whether spatial data is significantly clustered, dispersed, or random.

What are the two main methods of observing neighbors in GIS?

The Queen’s case and the Rook’s case are methods to define neighbor relationships in spatial analysis.

What does a Lagged Mean Plot show in spatial analysis?

It displays the weighted averages of neighboring features, showing how neighborhood values influence a given feature.

What does a steep line in Moran’s plot indicate?

A steep line indicates high spatial clustering, while a flat or negative line indicates randomness or high dispersion.

How can we interpret discrepancies in observed versus expected k-functions?

If the observed line is above the expected line in a k-function plot, it indicates spatial clustering.

Resolution

In remote sensing, it refers to the detail or quality of the data captured, including aspects like spatial, spectral, radiometric, and temporal resolution.

Spatial Resolution

Refers to the amount of detail visible in an image, measured by the size of pixels, e.g., Landsat TM = 30 m, Sentinel-2 = 10 m.

Spectral Resolution

Describes how a sensor samples the spectral curve, indicating the number of spectral bands captured, e.g., multispectral has 4-20 bands while hyperspectral can have hundreds.

Radiometric Resolution

The number of brightness levels an imaging system can record, also known as radiometric sensitivity, expressed in bits.

Temporal Resolution

A measure of the frequency of data acquisition, indicating how often a specific location is observed by the sensor.

Uncrewed Aerial Vehicles (UAVs)

Drones that are used for remote sensing, evolving from military uses to various commercial applications.

Multispectral Imagery

Data captured in a few broad spectral bands, allowing discrimination of materials but not identification.

Hyperspectral Imagery

Optical data with many narrow bands that can identify materials by representing detailed spectral signatures.

Spectral Mixture Analysis

A technique in remote sensing that assumes pixel reflectance is a linear combination of reflectance from different endmembers.

Structure from Motion (SfM)

A photogrammetric technique that creates 3D models from overlapping 2D images by matching features across the images.

Principal Component Analysis (PCA)

A dimensionality reduction method that simplifies hyperspectral data to a few principal components while retaining variance.

Georeferencing

The process of associating image data with real-world coordinates using GPS data and ground control points.

Cloud-Free Composites

Images that combine multiple captures to create a clearer view by averaging or selecting cloud-free observations.

Spectral Profiles

Graphs showing the reflectance of materials across different wavelengths, critical for identifying materials in hyperspectral data.

Visual Line of Sight (VLOS)

A regulatory requirement for UAV operations, meaning the pilot must keep the drone within sight during flight.

Dimensionality Reduction

The process of simplifying dataset complexity while maintaining essential information, often used in hyperspectral data analysis.

Active Remote Sensing

A system that provides its own source of energy, transmitting and receiving signals for observations regardless of light availability.

Passive Remote Sensing

Systems that detect available energy which is reflected or radiated from the terrain, limited by light conditions.

Wavelength

The distance between consecutive crests of a wave, usually measured in nanometers (nm) or micrometers (µm).

Frequency

The number of crests passing a given point in one second, typically measured in Hertz (Hz).

Polarization

The orientation of a wave's oscillations, typically characterized as vertical or horizontal.

Speckle

The ‘salt and pepper’ appearance in radar images caused by interference within the scattered field; it generates chaotic measurements.

Backscatter

The return signal of radar, which indicates the level of energy reflected back to the system from a surface.

Scattering Mechanisms

Different ways in which waves can scatter off surfaces, including surface backscattering, volume backscattering, and double-bounce backscattering.

Synthetic Aperture Radar (SAR)

A type of radar used in remote sensing that utilizes a small antenna to create a synthetic aperture, improving resolution.

Spatial Resolution

The ability of an imaging system to resolve features in the image, controlled by range and azimuth resolution.

GIS

Geographic Information Systems, a framework for gathering, managing, and analyzing spatial and geographic data.

Automation

The use of technology to perform tasks with minimal human intervention to improve efficiency and consistency.

Problem Solving

The process of identifying a problem and developing a plan to find a solution.

RS

Remote Sensing, the acquisition of information about an object or phenomenon without making physical contact.

Data Layers

Different sets of data that can be overlaid and analyzed in GIS applications.

Habitat Restoration

The process of returning a habitat to its original state with the goal of improving ecological health.

NDVI

Normalized Difference Vegetation Index, a graphical indicator used to analyze remote sensing measurements.

Fly from UK to Zanzibar

The process of traveling from the United Kingdom to Zanzibar typically involves planning major steps, such as identifying the departure and arrival airports.

Evaluation of Results

The systematic determination of a program's effectiveness, often through metrics like accuracy and correlation.

ModelBuilder

A visual programming tool in ArcGIS for building and automating geoprocessing workflows.

Python

A high-level programming language known for its readability and versatility, commonly used in GIS for automation.

Loops

A programming construct that repeats a block of code multiple times until a certain condition is met.

Comments in Code

Annotations in code, ignored by the interpreter, that explain what a specific section does for future reference.

Dictionaries in Python

A collection of key-value pairs in Python, similar to a database table.

Functions in Programming

Reusable blocks of code designed to perform a specific task, making programs more modular.

Classification Accuracy

A metric to evaluate how well a classification algorithm performs by comparing predicted results to actual data.

DEM

Digital Elevation Model, a raster image where each grid cell has a height value.

DSM

Digital Surface Model, measures the height of the top surface including objects like trees and buildings.

DTM

Digital Terrain Model, measures the height of the terrain without objects.

LiDAR

Light Detection and Ranging, a remote sensing method that uses laser light pulses to measure distances.

Point Cloud

A collection of data points in space representing the external surface of an object, often generated by LiDAR.

Full Waveform LiDAR

A method of LiDAR data collection that captures the full return signal to gather more information about complex environments.

Aerial Photography

A method for capturing photos of the earth from the air, often used in conjunction with DEM data collection.

Flow Accumulation

A process that calculates the number of upslope contributing cells in a Digital Elevation Model.

Filling Sinks

The process of addressing imperfections in a DEM that affect flow modeling by correcting internal drainage issues.

Global Ecosystem Dynamics Investigation (GEDI)

A satellite LiDAR mission that measures forest vertical structure and provides data for biomass estimation.

Remote Sensing

The technology of measuring the characteristics of an object or surface from a distance.

Optical Imagery

Most commonly used type of imagery in remote sensing; examples include Landsat, Sentinel-2, and MODIS.

Thermal Infrared

Records thermal energy emitted from the Earth’s surface, with no atmospheric scattering but significant absorption.

Synthetic Aperture Radar (SAR)

An active remote sensing system that generates its own energy and responds to the texture of the landscape.

LiDAR

Light Detection And Ranging; measures distance using laser and can produce detailed canopy height models.

Spectral Reflectance

The proportion of energy reflected at a specific wavelength from an object compared to the incoming energy.

Albedo

The ratio of all energy radiated by a surface compared to the incoming energy.

Dark Object Subtraction (DOS)

A method used to remove atmospheric reflectance by identifying dark objects assumed to have no surface reflectance.

Empirical Line Calibration

A method used for high-resolution data to adjust digital brightness values based on in situ measurements.

Orthorectification

The process of correcting the geometry of images to account for the Earth's topography.

Remote Sensing

The acquisition of information about an object or phenomenon without making physical contact with it.

GIS

Geographic Information System; a framework for gathering, managing, and analyzing spatial and geographic data.

Map Projections

A method of representing the curved surface of the Earth on a flat surface.

Datum

A set of parameters and control points defining the position and orientation of a reference ellipsoid with respect to the Earth.

Geoid

The equipotential surface that coincides with mean sea level of the Earth, if the oceans were in equilibrium.

WGS84

World Geodetic System 1984; the reference system used by the Global Positioning System (GPS).

Ellipsoid

A mathematically defined surface that approximates the shape of the Earth.

UTM

Universal Transverse Mercator; a grid system for determining horizontal positions on the Earth's surface.

Cylindrical Projection

A type of map projection where the Earth's surface is projected onto a cylinder.

Conic Projection

A type of map projection where the Earth's surface is projected onto a cone.

Azimuthal Projection

A type of map projection that projects the Earth's surface onto a plane.

Multi-Criteria Analysis

A decision-making process that evaluates multiple conflicting criteria.

Linear Reference System

A system used to describe the location of features along a linear route or path.

Raster Data

Data represented in a matrix of pixels; often used in remote sensing images.

Vector Data

Data represented using points, lines, and polygons to describe spatial features.

Mean Sea Level

The average height of the sea with reference to the geoid.

Coordinate System

A system that defines a point in space through numeric coordinates.

Map Distortion

The unavoidable differences introduced when projecting a 3D surface onto a 2D plane.

Standard Lines

Lines in a map projection where there is no distortion.

Equal Area Projection

A projection that maintains area relationships of all parts of the globe.

Conformal Projection

A projection that preserves local angles and shapes.

Electromagnetic Radiation Interactions

EM energy can be reflected, transmitted (refracted), or absorbed.These interactions occur with matter at various frequencies, affecting how electromagnetic waves propagate and interact with different materials.

Law of Reflection

The principle that states reflection follows specific angles of incidence (\thetai) and reflection (\thetar), where \thetai = \thetar.