GIS Lecture 15: Neighborhood and Terrain Analysis
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Questions and Answers

Which resolution type refers to the size of the instantaneous field of view in remote sensing?

  • Spectral resolution
  • Radiometric resolution
  • Temporal resolution
  • Spatial resolution (correct)

What is the effect of NDVI values closer to 1?

  • Suggests non-vegetated areas
  • Represents dense vegetation (correct)
  • Indicates bare soil
  • Denotes water bodies

What is the primary purpose of applying false-color composite images?

  • To increase image resolution
  • To measure atmospheric conditions
  • To capture more spectral bands
  • To enhance contrast between objects and background (correct)

How do hyperspectral imaging and multispectral imaging primarily differ?

<p>By the number of bands recorded (B)</p> Signup and view all the answers

Which type of remote sensing sensor relies on solar energy?

<p>Passive sensors (B)</p> Signup and view all the answers

What technology does LiDAR use to gather information?

<p>Laser light (D)</p> Signup and view all the answers

What is the concept of 'return' in remote sensing?

<p>The time taken for a signal to reflect back (A)</p> Signup and view all the answers

What does radiometric resolution refer to in remote sensing?

<p>The sensitivity to differences in electromagnetic energy (D)</p> Signup and view all the answers

What is one of the main advantages of aerial and satellite images?

<p>They offer long-term data records. (B)</p> Signup and view all the answers

Which of the following best describes reflection in the context of electromagnetic radiation?

<p>When radiation strikes a surface and bounces off. (C)</p> Signup and view all the answers

How is frequency defined in relation to wavelengths?

<p>The number of wavelengths passing a point per unit time. (D)</p> Signup and view all the answers

What characteristic is true of the spectral signature of vegetation?

<p>It shows high reflectance in the infrared spectrum. (B)</p> Signup and view all the answers

What is the primary purpose of orthogonal aerial photography?

<p>To provide true position ground feature displays. (C)</p> Signup and view all the answers

Which type of data does digital air photo imagery primarily represent?

<p>Raster data without a value attribute table. (D)</p> Signup and view all the answers

Which of the following types of resolution is commonly associated with raster data?

<p>Spatial resolution. (D)</p> Signup and view all the answers

What occurs during the absorption of radiation?

<p>Material takes in the radiation, converting it to internal energy. (D)</p> Signup and view all the answers

What is the primary purpose of analyzing flow direction in GIS?

<p>To identify the paths of steepest descent for water movement (C)</p> Signup and view all the answers

What advantage do aerial and satellite images provide in terrain analysis?

<p>They can capture high-resolution images over large areas efficiently (B)</p> Signup and view all the answers

How is flow accumulation calculated in raster data analysis?

<p>By counting the number of upstream cells draining into a specific cell (C)</p> Signup and view all the answers

What is a key characteristic of high-resolution raster data?

<p>It provides finer details and a clearer understanding of terrain (D)</p> Signup and view all the answers

What is the concept of wavelength and its significance in remote sensing?

<p>Wavelength affects radiation absorption and reflection characteristics (A)</p> Signup and view all the answers

What defines the difference between slope and aspect in terrain analysis?

<p>Slope quantifies steepness, whereas aspect indicates the direction the slope faces. (B)</p> Signup and view all the answers

Which of the following most accurately describes neighborhood analysis's 'moving window' concept?

<p>It involves a defined area that shifts dynamically for cell analysis. (C)</p> Signup and view all the answers

What is the primary use of a Digital Elevation Model (DEM) in terrain analysis?

<p>To interpret and analyze topographic features. (B)</p> Signup and view all the answers

Flashcards

Aerial images

Images taken from aircraft.

Satellite images

Images taken from satellites.

Spectral signature

Unique spectral response pattern of an object.

Vegetation spectral signature

Vegetation absorbs red and blue, reflects green, and has high infrared reflectance.

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Orthogonal aerial photography

Aerial photography perpendicular to the ground, correcting relief and tilt effects.

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Irradiance

Radiation incident on a surface.

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Raster data resolution

Describes the size of the raster/pixel and the number of colors.

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Reflection

Bouncing of electromagnetic radiation off a surface.

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Spatial Resolution

The size of the instantaneous field of view of a sensor. Often measured in area (e.g., square meters).

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Temporal Resolution

How often a sensor acquires data. Expressed as the time interval between data collections.

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Neighborhood Analysis

Analyzing data within specific areas (neighborhoods).

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Radiometric Resolution

The sensor's ability to distinguish small differences in electromagnetic energy.

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Zonal Function

Analyzing data within predefined regions (zones).

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Terrain Analysis

Interpreting geographic features, like the flow of rivers and the slopes of hills.

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Spectral Resolution

The number and width of the spectral regions a sensor records data from.

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DEM (Digital Elevation Model)

A digital representation of a terrain's elevation.

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NDVI

Normalized Difference Vegetation Index; a method to measure vegetation health using near-infrared and red light reflectance.

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False-Color Composite

An image where different spectral bands are displayed using different colors (typically Red, Green, Blue).

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Slope

Change in elevation over distance (rise over run).

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LiDAR

Light Detection and Ranging; an active remote sensing method using laser light to measure distances.

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Aspect

Direction a slope faces (expressed in degrees).

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Flow Direction

The direction water or other things flow downhill.

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Return (LiDAR)

Reflections from a surface back to the sensor used to calculate height.

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Flow Accumulation

Counting the number of upstream cells draining into a given cell.

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Study Notes

Lecture 15: Neighborhood and Zonal Analysis

  • Neighborhood analysis uses a moving window
  • Moving window dimensions define cells within the window
  • Output is cell-centered operations
  • Focal analysis moves one cell at a time to create overlapping neighborhoods
  • Zonal function applies operations to defined regions (zones)
  • Zonal statistics summarize data within specific zones (e.g., total population)

Lecture 15: Terrain and Terrain Analysis

  • Terrain analysis involves the interpretation of topographic features and understanding water flow patterns
  • Terrain is affected by flowing water (lakes/floods), influencing soil & food production
  • Terrain analysis uses GIS tools to interpret slope, aspect, viewshed, and elevation

Lecture 15: Terrain Models

  • Terrain models include elevation contours (vector), digital elevation models (DEMs), triangular irregular networks (TINs), 3D point clouds (LiDAR), and other various models
  • Models help in determining elevation changes and spatial relationships.

Lecture 16: Aerial and Satellite Imagery

  • Aerial images are taken from aircraft
  • Satellite images are taken from satellites
  • Advantages include reliable information, large spatial coverage over long timescales for environmental studies, and non-intrusive data collection methods.

Lecture 16: US Terrain Data

  • USGS and NOAA/FEMA provide high-resolution terrain data.
  • LiDAR is used in coastal areas for detailed terrain information.

Lecture 16: DEM Derivatives

  • DEM derivatives are calculated based on neighborhood analysis on DEMs
  • Derived attributes include slope, aspect, curvature, and flow direction.

Lecture 16: Slope and Aspect

  • Slope describes the change in elevation over the horizontal distance
  • Slope is measured in percent or degrees
  • Aspect refers to the direction a slope faces (e.g., north, south).

Lecture 16: Flow Direction, Accumulation, and Watersheds

  • Flow direction follows downhill gradients, coded by facet numbers.
  • Flow accumulation counts upstream cells draining into a given cell.
  • Watersheds are areas of land defined by the direction of water flow.

Lecture 17: Raster Data Resolution

  • Raster data resolution includes spatial (pixel size), temporal (data acquisition frequency), and radiometric (brightness levels) aspects
  • Sensors record data in spectral (e.g., blue, green, red, near-infrared) regions for different data analysis.

Lecture 17: NDVI

  • NDVI (Normalized Difference Vegetation Index) measures vegetation density.
  • NDVI values range from -1 to 1, with higher values indicating denser vegetation.
  • Higher NDVI values are associated with areas denser with vegetation.

Lecture 17: Orthogonal Aerial Photography

  • Orthogonal aerial photography captures images perpendicular to the ground.
  • The images remove the effects of terrain relief and camera tilt to show a feature's true position.

Lecture 17: Digital Air Photo Imagery

  • Digital air photo imagery includes raster data without value attributes.
  • Aerial images are collected in vertical views, and the sizes of the pixel resolution determine data quality.

Additional Considerations

  • The notes highlight key concepts and terms as instructed, focusing on the data for understanding rather than on the subjective analysis of the data.

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Related Documents

Study Guide 4 (Lectures 15-17) PDF

Description

This quiz covers the key concepts from Lecture 15 on Neighborhood and Zonal Analysis, as well as Terrain Analysis and Models. Understand how moving windows and zonal functions apply to geographical data, including topographic features and water flow patterns. Explore various models used in terrain analysis such as DEMs and TINs.

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