Remote Sensing Quiz
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Questions and Answers

What occurs when radiation 'bounces' off a target?

  • Transmission
  • Reflection (correct)
  • Absorption
  • Refraction

    • Specular reflection occurs when a surface is rough and energy is reflected uniformly in all directions.

    False

    What type of reflection results in a bright spot in an image?

    Specular reflection

    _____ occurs when radiation is absorbed by the target.

    <p>Absorption</p> Signup and view all the answers

    Which of the following reflects energy almost uniformly in all directions?

    <p>Diffuse reflection</p> Signup and view all the answers

    Match the type of reflection with its description:

    <p>Specular Reflection = Smooth surface causing directed reflection Diffuse Reflection = Rough surface causing scattered reflection Absorption = Radiation absorbed by the target Transmission = Radiation passing through a target</p> Signup and view all the answers

    What is a reflectance curve?

    <p>A graph showing the portion of incident energy reflected as a function of wavelength.</p> Signup and view all the answers

    The reflectance characteristics of vegetation depend on the properties of the _____ including the structure of the leaf canopy.

    <p>leaves</p> Signup and view all the answers

    What is the typical altitude range for remote sensing satellites in polar orbit?

    <p>600 - 800 km</p> Signup and view all the answers

    An inclination angle of 60 degrees allows observation of areas above 60 degrees latitude.

    <p>False</p> Signup and view all the answers

    What does the term 'repeat cycle' refer to?

    <p>The time in days between two successive identical orbits.</p> Signup and view all the answers

    A __________ orbit allows observation of the whole globe.

    <p>polar</p> Signup and view all the answers

    What is the speed of a polar satellite at 800 km altitude?

    <p>28,000 km/hour</p> Signup and view all the answers

    Satellites at geo-stationary orbit are typically located at an altitude of 800 km.

    <p>False</p> Signup and view all the answers

    What is the time required to complete one full orbit called?

    <p>Period</p> Signup and view all the answers

    Match the following orbit types with their characteristics:

    <p>Polar orbit = 600 - 800 km altitude, full globe coverage Geo-stationary orbit = 36,000 km altitude, fixed over one point on earth Inclination angle = Degrees between the orbit and the equator Repeat cycle = Time between two identical orbits</p> Signup and view all the answers

    What is the primary range of wavelengths that the human eye is sensitive to?

    <p>400 - 700 nm</p> Signup and view all the answers

    Rods contribute to colour vision in low light conditions.

    <p>False</p> Signup and view all the answers

    What type of receptors in the retina are responsible for colour perception?

    <p>Cones</p> Signup and view all the answers

    Colour perception occurs in the human eye and the associated part of the __________.

    <p>brain</p> Signup and view all the answers

    Match each type of cone with the wavelength it responds to:

    <p>Blue cone = Short wavelengths (450 nm) Green cone = Medium wavelengths (530 nm) Red cone = Long wavelengths (580 nm) Rods = Sensitivity to light, not color</p> Signup and view all the answers

    How are colors created on screens like televisions and computer monitors?

    <p>By mixing different amounts of red, green, and blue light</p> Signup and view all the answers

    Colour photography does not require an understanding of color perception theory.

    <p>False</p> Signup and view all the answers

    What is the function of cones in the human eye?

    <p>To send signals to the brain for color perception</p> Signup and view all the answers

    What does the term 'parallax' refer to in the context of measuring tree height?

    <p>The difference in positions of the tree top and base relative to photo centres</p> Signup and view all the answers

    Digital photogrammetric workstations (DPWs) replace analogue and analytical plotters completely.

    <p>False</p> Signup and view all the answers

    Name the three steps involved in the orientation process of a stereo model.

    <p>Inner orientation, relative orientation, absolute orientation</p> Signup and view all the answers

    The process of identifying identical points in both photographs during stereo model orientation is called __________.

    <p>relative orientation</p> Signup and view all the answers

    Match the following types of plotters with their descriptions:

    <p>Analogue Plotters = Used for direct plotting onto film Analytical Plotters = Utilize mathematical methods for 3D measurements Digital Photogrammetric Workstations = Incorporate modern digital techniques Stereovision = Creates an impression of depth in 3D models</p> Signup and view all the answers

    Which of the following is NOT a step in the stereo model orientation process?

    <p>Creating a simulation of tree height</p> Signup and view all the answers

    Visualization plays a significant role in the information extraction stage of remote sensing.

    <p>True</p> Signup and view all the answers

    What is the purpose of identifying 3D ground control points in absolute orientation?

    <p>To bring the 3D model to a known scale and level with respect to the terrain coordinate system.</p> Signup and view all the answers

    What is one benefit of using radar images in forestry applications?

    <p>They offer information about forest canopy and biomass.</p> Signup and view all the answers

    Radar technology can operate independently of weather or daylight conditions.

    <p>True</p> Signup and view all the answers

    Name two applications of radar in environmental monitoring.

    <p>Oil slick monitoring, hydrological modeling</p> Signup and view all the answers

    Radar images can help differentiate various land cover types such as urban areas, agricultural fields, and __________.

    <p>water bodies</p> Signup and view all the answers

    Match the radar application with its specific use:

    <p>Forest applications = Canopy and biomass analysis Agriculture = Crop identification Geology = Surface texture analysis Disaster monitoring = Earthquake assessment</p> Signup and view all the answers

    Which type of radar is used in the European ERS mission and Canadian Radarsat?

    <p>C-band</p> Signup and view all the answers

    Radar can only provide information related to the Earth’s surface.

    <p>False</p> Signup and view all the answers

    What is one of the types of information that radar provides for geological mapping?

    <p>Surface texture or roughness</p> Signup and view all the answers

    Which element is primarily used in standard image classification?

    <p>Hue</p> Signup and view all the answers

    Stereoscopic vision relies on images being viewed from the same position.

    <p>False</p> Signup and view all the answers

    What term is used for pairs of images that can be viewed stereoscopically?

    <p>stereograms</p> Signup and view all the answers

    The process of directing both eyes to a point of interest is known as __________.

    <p>convergence</p> Signup and view all the answers

    Match the following tools with their primary applications:

    <p>Pocket stereoscopes = Mapping applications related to vegetation Mirror stereoscopes = Geomorphology studies Photogrammetric plotters = Topographic mapping Stereoscopic projection in colors = Enhancing depth perception</p> Signup and view all the answers

    What is the main reason for the limitation of automated methods in image interpretation?

    <p>They focus solely on hue.</p> Signup and view all the answers

    Experienced individuals can achieve stereo vision by adjusting the distance of two overlapping photos without any additional equipment.

    <p>True</p> Signup and view all the answers

    Stereoscopic vision is important for interpreting natural and man-made __________ from image data.

    <p>features</p> Signup and view all the answers

    Study Notes

    Remote Sensing Course Outline

    • GEOL 315 covers Introduction to Remote Sensing and GIS
    • Topics include Introduction to remote sensing, Electromagnetic energy and remote sensing, Sensors and platforms, Aerial cameras, Multispectral scanners, RADAR, Remote sensing below the ground surface, Radiometric aspects, Geometric aspects, Image enhancement and visualization, Visual image interpretation, and Digital image classification.

    Spatial Data Acquisition

    • Georeferenced data is used by many disciplines, not just geology, for collection, analysis, and decision-making. Data represents information for a computer; information is data interpreted by humans.
    • Spatial data, often spatio-temporal, is crucial for applications like geological mapping.

    Ground-Based and Remote Sensing Methods

    • Spatial data acquisition has two main types:
      • Ground-based methods utilize field observations, in-situ measurements, and land surveying in the real world.
      • Remote sensing methods use image data from sensors like aerial cameras, scanners, or radar to create a representation of the real world. Remote sensing analysis is performed on the acquired image data.

    Remote Sensing Definitions

    • Two definitions of remote sensing include:
      • The science of acquiring, processing, and interpreting images recording interactions between electromagnetic energy and matter.
      • The science and art of obtaining information about an object, area, or phenomenon via analysis of data taken by a device not in contact with the object.

    Application of Remote Sensing

    • Remote sensing generates image data related to the Earth's electromagnetic properties, which can be linked to real-world parameters or features.
    • Combining remote sensing with ground data yields the best results.
    • Remote sensing provides efficient area coverage compared to ground surveys, e.g., in aeromagnetic and ground magnetic surveys.
    • Remote sensing initially provides surface information with limitations, requiring additional models for subsurface characteristics.

    Remote Sensing Process and Topics

    • Remote sensing involves a process with image data, observations, and spatial databases.
    • Key topics include electromagnetic energy, sensors and platforms, radiometric aspects, geometric aspects, image enhancement and visualization, visual image interpretation, and digital image classification.

    Electromagnetic Energy and Remote Sensing

    • Remote sensing relies on measuring electromagnetic (EM) energy, primarily from the sun (visible light, heat, UV).
    • Some sensors detect energy emitted by the Earth itself.
    • The EM spectrum encompasses various wavelengths from gamma rays (most energetic) to radio waves (least energetic).

    Waves and Photons

    • EM energy can be described as both waves and photons (energy particles).
    • EM waves are characterized by oscillating electric and magnetic fields perpendicular to each other and the direction of travel.
    • Wavelength (distance between waves) and frequency (number of cycles per unit time) are inversely related.
    • Energy of a photon is proportional to its frequency (and therefore inversely to wavelength).

    Sources of EM Energy

    • All matter above absolute zero emits EM energy due to molecular motion.
    • The amount of emitted energy depends on temperature, emissivity, and wavelength. Higher temperatures relate to greater contribution from shorter wavelengths.

    Electromagnetic Spectrum

    • All matter emits EM waves across a broad spectrum (range of wavelengths) from gamma rays to radio waves.
    • Remote sensing utilizes specific sections of the EM spectrum to generate relevant information about the Earth's surface.

    Active and Passive Remote Sensing

    • Passive remote sensing relies on natural energy sources, like sunlight, and measures reflected or emitted energy.
    • Active remote sensing systems provide energy, e.g., radar and lasers, and measure the energy reflected back to the sensor.
    • Passive methods operate during daylight hours, while active sensors work day and night.

    Energy Interaction in the Atmosphere

    • EM energy interacts with the atmosphere through absorption, transmission, and scattering.
    • Gas molecules in the atmosphere absorb solar radiation particularly water vapor, ozone, and carbon dioxide.
    • Absorption and scattering also affect energy transmission resulting in either reflected, transmitted, or absorbed energy at surface material.
    • Atmospheric transmittance describes the proportion of energy that passes through the atmosphere at specific wavelengths.

    Atmospheric Scattering

    • Rayleigh scattering is caused by particles smaller than the wavelength of light.
    • Rayleigh scattering is more effective with short wavelengths (like blue light), making the sky appear blue.
    • Mie scattering occurs when the particle size is similar to or larger than the wavelength.
    • Non-selective scattering occurs when particles substantially larger than the wavelength (e.g., water droplets in clouds) interact with radiation across the whole visible spectrum, resulting in white light.

    Energy Interaction in the Earth's Surface

    • Reflection, absorption, and transmission processes of EM energy by surface materials are important factors for interpreting remote sensing data.
    • Specular reflection is from smooth surfaces, while diffuse reflection is from rough surfaces, scattering energy uniformly.
    • Characteristics of visible reflected energy (spectral reflectance curves) reveal information about material compositions, e.g., vegetation, bare soil, and water.

    Sensors and Platforms

    • Sensors, often mounted to static or moving platforms (aircraft or satellites), measure EM energy reflected or emitted from the Earth's surface.
    • Sensor types include gamma-ray spectrometers, multispectral scanners, thermal scanners, laser scanners, and radar altimeters.

    Platforms - Airborne Remote Sensing

    • Airborne platforms, such as aircraft, allow data collection from various heights and are suitable for acquiring information from specific areas.
    • Key factors for aerial photography missions include scale, required percentage of overlap, flight line conditions, and temporal conditions to ensure data accuracy.

    Platforms - Spaceborne Remote Sensing

    • Satellites collect data from space and orbit, allowing imaging of entire regions, e.g. oceans to determine relevant details of a specific area.
    • Key factors for satellite imagery missions include altitude, inclination angle, period, and repeat cycle.
    • These factors affect the measurements and speed and quality of information extracted.

    Image Data Characteristics

    • Image data comprises various details that are essential for interpreting the data. These important components include image size, number of bands, quantization, spatial resolution, ground pixel size.

    Visual Image Interpretation

    • Visual interpretation is a key part of remote sensing data analysis, utilizing human observation.
    • Key elements for interpreting images include tone, hue, texture, shape, size, pattern, and association.

    Image Enhancement and Visualization

    • Image enhancement methods improve the visualization of image data.
    • Techniques such as histogram matching and atmospheric corrections can improve image contrast and detail.

    Radiometric Aspects

    • Radiometric aspects deal with image data corrections including cosmetic rectification (errors and noise) and atmospheric corrections (haze, sun angle, atmospheric effects).

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    Related Documents

    GEOL 315 Introduction to Remote Sensing and GIS PDF

    Description

    Test your knowledge on remote sensing concepts, including reflection types, satellite orbits, and reflectance characteristics. This quiz covers key principles related to how radiation interacts with surfaces and the implications for satellite observations. Perfect for students studying Earth science or remote sensing.

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