Relief Modelling and Digital Elevation Models
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Questions and Answers

What is primarily displayed by contour maps?

  • Population density
  • Variation of altitude (correct)
  • Climate zones
  • Vegetation types

A shaded relief map uses color gradients to represent elevation changes.

False (B)

What does the term 'aspect' refer to in the context of terrain models?

Compass direction of maximum rate of change of altitude

The _____ network is crucial for delineating areas for flooding analysis.

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

Match the terrain features with their descriptions:

<p>Spot Heights = Specific points of high elevation Hachures = Lines that indicate slope direction Layer Tints = Coloring of different elevation ranges Relief Model = Three-dimensional representation of terrain</p> Signup and view all the answers

Which of the following components is NOT a part of the slope model in a Digital Elevation Model (DEM)?

<p>Peak height (A)</p> Signup and view all the answers

A drainage basin is characterized by areas that direct water flow to a specific point.

<p>True (A)</p> Signup and view all the answers

What is the primary use of analytical stereoplotters in creating altitude matrices?

<p>To obtain quantitative measurements from aerial photographs</p> Signup and view all the answers

What is a major disadvantage of thick and short hachures on steep slopes?

<p>They can obscure other map details. (A)</p> Signup and view all the answers

Vertical exaggeration can accurately represent actual elevations on maps.

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

What method creates vector-based representations of the physical land surface?

<p>Triangulated Irregular Network</p> Signup and view all the answers

A Digital Elevation Model (DEM) is a digital representation of ground surface ________.

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

Match the following terms with their descriptions:

<p>Hachures = Lines indicating slope steepness Layer Tints = Color variations representing elevation ranges Spot Heights = Exact elevation points on a map Shading = Technique to depict relief on a map</p> Signup and view all the answers

What is a common use of Digital Elevation Models?

<p>Extracting terrain parameters (D)</p> Signup and view all the answers

Lower scale maps demonstrate less vertical exaggeration.

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

What does a larger ratio of vertical scale to horizontal scale indicate on a map?

<p>Greater vertical exaggeration</p> Signup and view all the answers

Gridding methods can help in creating accurate ________ maps.

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

Which of the following is NOT a use of DEM?

<p>Creating traditional paper maps (A)</p> Signup and view all the answers

What is a disadvantage of using spot heights for elevation indication?

<p>They do not give elevation information between certain points. (B)</p> Signup and view all the answers

Shading is used to show the general features of land where relief is low and slopes are gentle.

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

What effect do hachures create when illustrating terrain features?

<p>An effect similar to shading.</p> Signup and view all the answers

In layer tints, _____ tones are used for higher elevations.

<p>warm oranges, brown, red</p> Signup and view all the answers

Match the following methods with their advantages:

<p>Spot Heights = Simple and very accurate for selected points Shading = Provides a 3D effect Hachures = Facilitates visual recognition of terrain features Relief Model = Most legible of all methods representing relief</p> Signup and view all the answers

Which of the following is true about layer tints?

<p>Each elevation zone is marked with a distinctive color or tone. (A)</p> Signup and view all the answers

Relief models provide a two-dimensional representation of terrain.

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

What is the primary use of shading in elevation mapping?

<p>To enhance the readability of contours.</p> Signup and view all the answers

Hachures are rows of short, nearly _____ lines used to express relief.

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

What is the main disadvantage of using a relief model?

<p>It requires too much space. (D)</p> Signup and view all the answers

Flashcards

Spot Heights

Indicates elevations at specific points (benchmarks, hilltops, depressions, road intersections) on a map.

Relief Model

Represents terrain as a 3D miniature with accurate horizontal and vertical scales.

Shading

Shows general terrain features using light and shadow effects to represent high areas and steep slopes.

Hachures

Uses short, parallel lines whose spacing, weight, and direction create a visual effect similar to shading.

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Layer Tints

Displays elevation zones with distinctive colors or tones between contour lines.

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Digital Elevation Model (DEM)

A map that shows the shape of the land using contour lines.

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Relief Methods

Methods used to represent the shape of the land on a map.

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Contours

Contours are specific lines that connect points with the same elevation.

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Layer Tints

Tints are colors or tones used in layer tinting to represent different elevation zones.

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Contours

They represent areas of equal elevation and are used to show the shape of the land.

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Altitude Matrix (DTM)

A regular grid of data points obtained from aerial photos, representing altitude values over an area. Used for calculations like contours and slopes.

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What are contour maps?

A map that shows variations in elevation using contour lines. Each line connects points of equal elevation.

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TIN (Triangulated Irregular Network) Model

A way to represent 3D terrain using triangles. Each triangle connects three data points, forming a triangular network.

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What is slope in a DEM?

A representation of the steepness of a surface at a given point. It is the maximum rate of change of altitude.

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What is aspect in a DEM?

The compass direction of the steepest descent on a surface. It indicates the direction of maximum altitude change.

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What is shaded relief?

A visual representation of terrain, simulating how light would illuminate a surface. It enhances topographic features by adding shadows and highlights.

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What is drainage network delineation?

The process of identifying and mapping all areas where water flows downhill, ultimately creating hydrological networks.

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How is drainage network analysis useful?

Used to analyze flooding potential, understand water flow patterns, and assess risks like landslides.

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Contour Lines - Hachures

A method of representing a 3D surface using lines drawn perpendicular to the contour lines, creating a visual effect of raised relief.

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Vertical Exaggeration

A scale used to exaggerate vertical features on maps, plans, and technical drawings, emphasizing differences in elevation.

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Triangulated Irregular Network (TIN)

A vector-based representation of terrain using irregularly distributed points connected by lines to form triangles. It provides a flexible way to represent varying terrain complexity and elevation.

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Gridding Methods

A process of creating a grid over a map area and interpolating elevation data to create a smoother surface representation. Different gridding methods can yield different interpretations of the data.

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DEM Products: Block Diagrams, Profiles, and Horizons

A type of DEM product used for various applications, including generating block diagrams, profiles, and horizons. They help visualize terrain structure and elevation variations.

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DEM Products: Aspect Maps

A type of DEM product used for visualizing the direction of slopes on a terrain. It is useful for understanding water flow, erosion patterns, and other landscape features.

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DEM Products: Slope Maps

A type of DEM product used for various applications, including geomorphological studies and run-off estimations. It helps visualize the slope angle and understand terrain morphology.

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DEM Products: Shaded Relief Maps

A type of DEM product used for geomorphological studies, erosion estimations, and for creating visually appealing representations of terrain.

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DEM Products: Line of Sight Analysis

A type of DEM product used for analyzing the visibility between two points, taking into account terrain obstructions. It is useful for planning communication towers, line-of-sight analysis, and other applications.

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Study Notes

RELIEF MODELLING AND DIGITAL ELEVATION MODEL (DEM)

  • Relief methods are used for representing the shape of land
  • Spot heights: Indicate elevation at specific points (e.g., benchmarks, hilltops), accurate but don't show the overall shape
  • Shading: Creates light and shadow based on an assumed light source from the northwest, good for visualizing general relief and steepness
  • Hachures: Short parallel lines showing slope direction and steepness, effective for areas with varied slopes
  • Layer tints: Use different colors or tones to represent elevation zones; easy for large-scale maps but may not show internal variations
  • Relief model: 3D representation of terrain; suitable for visualizing details and educating various professionals

LAYER TINTS

  • Use distinctive colors or tones to represent elevation
  • Lighter tones for higher elevations, darker for lower
  • Colors (e.g., cool greens for lower, warm oranges/browns/reds for higher)
  • Disadvantage: Doesn't always show internal variations within an elevation zone

RELIEF MODEL

  • 3D representation, good for visualizing terrain features
  • Horizontal and vertical scales necessary for accuracy
  • Useful for instructing, showcasing terrain to the public, and assisting geologists, geographers, and engineers in special studies
  • Advantages: Easy to visualize, great for representing terrain
  • Disadvantages: Requires storage space and transportation

DIGITAL ELEVATION MODEL (DEM)

  • Digital representation of ground surface topography
  • Any representation reflecting continuous elevation variations
  • Can represent terrain with elevation data only
  • Used in various fields: topographic mapping, engineering design, etc.

USES OF DEM

  • Extracting terrain parameters
  • Engineering and infrastructure design
  • 3D landform visualization
  • Military purposes (weapons guidance systems, pilot training)
  • Landscape design and planning
  • Flight simulations, modeling environmental aspects
  • Creating physical models, visualizing terrain
  • Reducing gravity measurements, estimating run-off/erosion
  • Producing slope maps, aspect maps, shaded relief maps

ALTITUDE MATRIX

  • Regular grid obtained from stereoscopic aerial photographs
  • Use in calculations for contours, slopes, angles, aspects, hillshading and basin delineations, and automatic calculations
  • Easy for acquiring data but data redundancy exists in uniform areas
  • Can't adapt well to diverse relief complexity without changing the grid

TRIANGULATED IRREGULAR NETWORK (TIN)

  • Vector-based representation of the physical land surface (or sea floor)
  • Nodes with X, Y and Z coordinates, arranged in triangles.
  • Point density increases as terrain variation increases, a flexible method
  • Require visual inspection to control the network.

GRIDDING METHODS

  • Generating contour maps & other representations through XYZ coordinates
  • Allows generation of accurate maps from dispersed data, which needs interpolation
  • Different interpolation methods will yield varied outcomes

DEM PRODUCTS

  • Block diagrams, profiles, and horizons
    • Useful for visualizing elevation changes and quantitative variables
  • Contour maps
    • Can be easily produced from altitude matrices based on specified height classes using different colors/tones

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Description

Explore various techniques used in relief modelling and digital elevation representation. This quiz covers concepts like spot heights, shading, hachures, and layer tints, helping you understand the visualization of terrain. Perfect for geography and environmental science enthusiasts.

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