Map Projection Concepts

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Questions and Answers

What is a key feature of conical projections with two standard parallels?

All parallels are arcs of concentric circles. (correct)

All parallels are straight lines.

Meridians are curved lines.

Scale is true only at one standard parallel.

Which type of land feature can be accurately represented using this projection?

Coastal areas

Large mountain ranges

Dense forests

Long narrow strips of land (correct)

What happens to distances between standard parallels in a conical projection with two standard parallels?

They are longer than actual distances.

They vary depending on latitude.

They remain constant.

They are shorter than actual distances. (correct)

For which geographical areas is the conical projection with two standard parallels especially suitable?

Mid-latitudinal areas Signup and view all the answers

How do the meridians behave in conical projections with two standard parallels?

They are straight lines radiating from the pole. Signup and view all the answers

What distinguishes simple conical projection with one standard parallel from that with two?

One provides accurate scale only in the center. Signup and view all the answers

In a conical projection, what happens to the scale along the meridians?

It is true along all meridians. Signup and view all the answers

Which mode of transportation can be effectively shown along the standard parallel in this projection?

Railways Signup and view all the answers

What is a characteristic of perspective map projections?

They utilize a source of light to project the image. Signup and view all the answers

What characterizes the cylindrical equal area projection?

Scale is true only along the equator. Signup and view all the answers

What is a key limitation of cylindrical projections?

Distortion increases as we move towards the pole. Signup and view all the answers

Which type of surface is classified as developable?

A cone. Signup and view all the answers

Which feature is true of Mercator’s Projection?

Parallels and meridians intersect at right angles. Signup and view all the answers

Cylindrical projections are obtained by:

Covering the globe with a cylindrical surface. Signup and view all the answers

In which scenario is the cylindrical equal area projection best utilized?

Mapping the distribution of tropical crops. Signup and view all the answers

What defines an oblique projection?

It is tangential to a point between the pole and the equator. Signup and view all the answers

What maintains correct directions in Mercator’s Projection?

Correct bearing produced by straight lines. Signup and view all the answers

Which of the following is NOT a type of developable surface for projections?

Spherical. Signup and view all the answers

What is a characteristic of the Universal Transverse Mercator (UTM) Coordinate System?

Each zone is a different Transverse Mercator projection. Signup and view all the answers

Mathematical or conventional projections are described as:

Based solely on mathematical computations. Signup and view all the answers

What is the primary purpose of map projection?

To transform spherical features onto a flat surface Signup and view all the answers

Which azimuthal projection is best for plotting short routes due to its representation of great circles?

Gnomonic Projection Signup and view all the answers

Which statement about the scale in the cylindrical equal area projection is accurate?

The scale varies significantly at higher latitudes. Signup and view all the answers

Which statement is true regarding zenithal projections?

They are projected onto a flat surface when it touches the globe at a point. Signup and view all the answers

Which of the following accurately describes the process of creating a map projection?

Selecting a model, transforming coordinates, and reducing scale Signup and view all the answers

What is a key characteristic of the gnomonic projection with regards to the hemisphere it can present?

It can present less than a hemisphere at a time Signup and view all the answers

What is an implication of the projection being non-orthomorphic?

The areas depicted are accurate, but shapes are distorted. Signup and view all the answers

What are parallels of latitude?

Circles that run horizontally around the globe, parallel to the equator Signup and view all the answers

How are normal projections characterized?

They touch the globe at the equator. Signup and view all the answers

How are meridians of longitude represented on a globe?

As semi-circles drawn from one pole to the other Signup and view all the answers

Which projection is considered to be conformal but not equal area?

Stereographic Projection Signup and view all the answers

What type of distortion does the orthographic projection experience?

Distorts shape and area near the edges Signup and view all the answers

What does the term 'reduced earth' refer to in cartography?

A smaller version of the globe model on flat paper Signup and view all the answers

Which projection commonly used for polar aspects is known for its scale being stretched by perspective?

Stereographic Projection Signup and view all the answers

What is an essential characteristic of the model used in map projection?

It can either be a sphere or an ellipsoid Signup and view all the answers

In digital cartography, when is the scale reduction typically performed?

Last after transforming coordinates Signup and view all the answers

What is a significant property of conventional projections?

They are pure-mathematical constructions designed for the whole sphere Signup and view all the answers

Why should the gnomonic projection be avoided for measuring distances?

The distortion of properties increases away from the center point Signup and view all the answers

Why are parallels of latitude not all equal in length?

They diminish near the poles Signup and view all the answers

Which projection is not conformal, nor equal area, and distorts shape and area near edges?

Orthographic Projection Signup and view all the answers

What is a characteristic of conical projections regarding the representation of meridians?

Meridians are generally represented as straight lines. Signup and view all the answers

Why are conic projections not suitable for world maps?

They cause severe distortions in the opposite hemisphere from the standard parallel. Signup and view all the answers

What happens to the scale of a conical projection away from the standard parallel?

The scale is exaggerated as distance increases. Signup and view all the answers

Which of the following is a property of a simple conical projection with one standard parallel?

All parallels are arcs of concentric circles. Signup and view all the answers

What type of projection is illustrated by a cone that touches a globe along a specific parallel of latitude?

Conical projection. Signup and view all the answers

Which statement best describes the representation of the pole in a simple conical projection?

The pole is represented as an arc of a circle. Signup and view all the answers

What is one of the limitations of using conic projections for large area representations?

They cause larger distortions near the equator and poles. Signup and view all the answers

What is the primary use of conic projections in cartography?

Representing weather elements and navigation routes. Signup and view all the answers

Study Notes

Map Projection

Map projection is the method of transferring the graticule of latitude and longitude onto a plane surface.
It is also the transformation of the spherical network of parallels and meridians onto a plane surface.
Earth is a geoid, not a perfect sphere.
A globe is the best model of Earth, accurately showing shapes and sizes of continents and oceans, as well as directions and distances.
The globe is divided into sections by lines of latitude and longitude.
The horizontal lines represent latitude, and the vertical lines represent longitude.
The network of parallels and meridians is called a graticule. This network aids in map creation.
Transforming the graticule from a globe to a flat surface (a map) creates distortions.
Creating a map projection involves three steps:
- Selecting a model for the Earth's shape (sphere or ellipsoid).
- Transforming geographic coordinates (latitude and longitude) to plane coordinates (eastings and northings).
- Reducing the scale.

Elements of Map Projection

Reduced Earth: A reduced-scale model of the Earth, represented on a flat surface. It is approximately spheroid, with the polar diameter being shorter than the equatorial diameter. This allows transferring the graticule onto the map.
Parallels of Latitude: Circles parallel to the Equator, maintaining a uniform distance from the poles. They are not of equal length. They range from a point at each pole up to the circumference at the equator, and are demarcated as 0° to 90° North and South.
Meridians of Longitude: Semi-circles extending north-south from pole to pole. Each meridian lies entirely in its plane, but all intersect at right angles along the Earth's axis. One meridian, the Greenwich Meridian, is designated as 0° longitude serving as a reference point.
Global Properties:
- Distances between points.
- Shapes of regions.
- Sizes/areas of regions (accurately).
- Directions of points relative to each other.

Properties of Map Projection

Map projections involve altering area, shape, distance, and direction to fit a 3D sphere onto a 2D map.
This alteration is essential due to changing from a 3D representation to a 2D representation.
The spherical Earth surface is deformed or manipulated (torn, sheared, or compressed) to make it onto a flat surface.
Four major properties: area, shape, distance, and direction.
Area and shape are mutually exclusive (meaning only one can be accurately maintained).
Distance and direction can coexist with any other property, but cannot be accurate everywhere on the map.

Map Distortion

Distortion is unavoidable in map-making.
The degree of distortion varies across the map.
Distortion is lowest at points or lines where the map surface intersects the globe.

Classification of map projections

Drawing Techniques: projections are classified into perspective, non-perspective, and conventional or mathematical.
Perspective projections: use a light source to project the image of the globe's graticule onto a flat surface.
Non-perspective projections: do not use a light source; instead, these are derived through mathematical computations.
Conventional projections: are derived purely through mathematical computations and thus do not utilize a light source.
Developable Surface: A surface that can be flattened without distortion, onto which the graticule can be projected. Examples include cylinders, cones, and planes. A sphere is a non-developable surface.
Classification based on developable surface: Cylindrical, Conical, and Zenithal projections.

Types of Map Projections

Cylindrical Projections: Earth's surface is projected onto a cylinder, which is then unrolled as a rectangle. Common types are Mercator and Lambert's original cylindrical equal area.
- Mercator is conformal (maintaining shape).
- Scale distortion is greater at higher latitudes.
- Useful for navigation because it preserves angles.
Conical Projections: Earth's surface is projected onto a cone which touches the Earth's surface along a parallel.
- Presents the best projection for mid-latitude areas (for large longitudinal and small latitudinal areas).
Zenithal (Azimuthal) Projections: Earth's surface is projected onto a flat plane that touches the Earth at a point or along a line.
- There are three types (normal, oblique, and polar), depending on the plane's orientation.
- Useful for showing areas around one particular area or region because it maintains direction.
- Gnomonic projection (a type of azimuthal projection). The lines on this type of projection are straight lines that represent great circles.
Conventional Projections: Using purely mathematical computations, instead of a light source. Various types such as Sanson-Flamsteed (sinusoidal), Aitoff's and Mollweide's projections.

UTM Coordinate System

Universal Transverse Mercator (UTM) is a coordinate system that uses a transverse Mercator projection.
It divides the Earth into 60 zones, based on six-degree longitude intervals.
Uses meters as units, making calculations easier.

Map Projection Suitability and Selection

Consider the map's purpose when selecting a projection (e.g., area, shape, distance, direction).
Geographic location influences the selection of projections (distortion varies across locales).
Larger areas typically require different projections than smaller, localized areas to maintain accuracy.

Aspects of Map Projections

Projection aspect (normal, transverse, oblique): Refers to the orientation of the projection plane relative to Earth's axis. Normal is parallel, transverse is perpendicular, and oblique is non-parallel, non-perpendicular.

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Description

This quiz covers the fundamentals of map projection, including the processes of transforming the Earth's graticule onto a plane surface. It explores the differences between globes and maps, including the challenges of distortion during projection. Test your knowledge on the methods and models used in map making.