science

List of map projections

List of map projections is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand List of map projections rather than just read about it. In short: This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise notable. Because there is no limit to the number of possible map projections, there can be no comprehensive list.

Key takeaways

List of map projections belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect List of map projections to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of List of map projections from memory before moving on to harder problems.

Reference excerpt

This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise notable. Because there is no limit to the number of possible map projections, there can be no comprehensive list. The types and properties are described in § Key.

Table of projections

*The first known popularizer/user and not necessarily the creator.

Key

Type of projection surface Cylindrical In normal aspect, these map regularly-spaced meridians to equally spaced vertical lines, and parallels to horizontal lines. Pseudocylindrical In normal aspect, these map the central meridian and parallels as straight lines. Other meridians are curves (or possibly straight from pole to equator), regularly spaced along parallels. Conic In normal aspect, conic (or conical) projections map meridians as straight lines, and parallels as arcs of circles. Pseudoconical In normal aspect, pseudoconical projections represent the central meridian as a straight line, other meridians as complex curves, and parallels as circular arcs. Azimuthal In standard presentation, azimuthal projections map meridians as straight lines and parallels as complete, concentric circles. They are radially symmetrical. In any presentation (or aspect), they preserve directions from the center point. This means great circles through the central point are represented by straight lines on the map. Pseudoazimuthal In normal aspect, pseudoazimuthal projections map the equator and central meridian to perpendicular, intersecting straight lines. They map parallels to complex curves bowing away from the equator, and meridians to complex curves bowing in toward the central meridian. Listed here after pseudocylindrical as generally similar to them in shape and purpose. Retroazimuthal Direction to a fixed location B (by the shortest route) corresponds to the direction on the map from A to B. Other Typically calculated from formula, and not based on a particular projection Polyhedral maps Polyhedral maps can be folded up into a polyhedral approximation to the sphere, using particular projection to map each face with low distortion.

Properties Conformal Preserves angles locally, implying that local shapes are not distorted and that local scale is constant in all directions from any chosen point. Equal-area Area measure is conserved everywhere. Compromise Neither conformal nor equal-area, but a balance intended to reduce overall distortion. Equidistant All distances from one (or two) points are correct. Other equidistant properties are mentioned in the notes. Gnomonic All great circles are straight lines. Perspective Can be constructed by light shining through a globe onto a developable surface.

See also 360 video projection List of national coordinate reference systems Snake Projection

Notes

Further reading Snyder, John P. (1987). Map projections – A working manual (PDF). U.S. Geological Survey Professional Paper. Vol. 1395. Washington, D.C.: U.S. Government Printing Office. doi:10.3133/pp1395. Retrieved 2019-02-18. Snyder, John P.; Voxland, Philip M. (1989). An Album of Map Projections (PDF). U.S. Geological Survey Professional Paper. Vol. 1453. Washington, D.C.: U.S. Government Printing Office. doi:10.3133/pp1453. Retrieved 2019-02-18.

Illustrations

Worked examples

Example 1 — a first encounter with List of map projections

Start with the simplest possible case. Write down what List of map projections claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to List of map projections before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about List of map projections ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of List of map projections

In research: List of map projections appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses List of map projections in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: List of map projections is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lists of maps, Map projections, so understanding it makes those chapters shorter.
In everyday life: Look for List of map projections outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study List of map projections in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what List of map projections means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain List of map projections out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is List of map projections in simple terms?

Why does List of map projections matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study List of map projections?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on List of map projections.