m a cartographer.

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Map Projections

Why Every Map Distorts Reality — and Why That Is Normal

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A map is not reality.

It is a transformation.

The Earth is a sphere (more precisely, an oblate spheroid).
A map is flat.

To transfer curved space onto a plane, distortion is unavoidable.

There is no “perfect” projection.

There is only a projection appropriate for your task.

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What Is a Map Projection?

A map projection is a mathematical method of converting geographic coordinates (latitude and longitude) into flat, two-dimensional coordinates.

Every projection transforms:

• Shape

• Area

• Distance

• Direction

You cannot preserve all four simultaneously.

You must choose what matters.

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The Four Types of Distortion

Understanding distortion is critical for professional cartography.

1. Shape Distortion

Objects may become stretched or compressed.

Example:
Greenland appears much larger in Mercator projection than it actually is.

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2. Area Distortion

Some projections preserve shape but distort size.

Equal-area projections preserve true size relationships.

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3. Distance Distortion

Distances may be accurate only along specific lines or directions.

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4. Direction Distortion

Certain projections preserve compass bearings, others do not.

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There Is No Perfect Projection

This is one of the most important principles in cartography.

If someone says:

“This projection is correct.”

They are wrong.

The correct question is:

“Correct for what purpose?”

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Common Projections Used in Modern Cartography

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Mercator Projection

Most commonly used for web maps.

Advantages:

• Preserves angles

• Useful for navigation

• Rectangular grid

Disadvantages:

• Extreme area distortion near poles

Suitable for:

• City maps

• Navigation

• Small regional projects

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Equal-Area Projections

Preserve true area relationships.

Useful for:

• Thematic maps

• Statistical visualization

• Environmental maps

Shapes may appear distorted,
but area is correct.

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Robinson Projection

A compromise projection.

Balanced distortion of area and shape.

Used in:

• Educational atlases

• World maps

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Goode Homolosine Projection

Interrupts oceans to preserve landmass proportions.

Suitable for:

• Continental emphasis

• Thematic world maps

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Dymaxion Projection

Projects Earth onto an icosahedron.

Advantages:

• Preserves continental continuity

• Minimizes distortion across land

Disadvantages:

• Visually unconventional

• Requires careful design

Used in:

• Experimental cartography

• Global thematic projects

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Choosing a Projection for Print Maps

For most city maps:

Projected coordinate systems or Mercator-based systems are acceptable.

For country maps:

Consider equal-area or compromise projections.

For world maps:

Avoid naive Mercator unless distortion is intentional.

Projection choice must match:

• Map scale

• Geographic extent

• Purpose of the map

• Audience expectations

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Practical Rule for Beginners

If you are mapping:

• A single city → local projected system

• A region → suitable national projection

• A continent → equal-area or compromise

• The world → avoid web Mercator

Projection should serve clarity.

Not habit.

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Projection and Production Workflow

Projection affects:

• Scale accuracy

• Label spacing

• Line curvature

• Generalization behavior

• File export precision

Changing projection mid-production is risky.

Choose projection at the beginning.

Stick with it.

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What Happens If You Ignore Projection

You may experience:

• Misaligned layers

• Incorrect distances

• Distorted shapes

• Printing inconsistencies

• Inaccurate measurements

Projection mistakes are subtle.

They become visible only when it is too late.

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Professional Mindset

Projection is not decoration.

It is structural geometry.

Treat it as:

• Engineering decision

• Mathematical transformation

• Foundational layer of the map

Not as a stylistic option.

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Summary

A map projection:

• Converts spherical Earth to flat space

• Introduces unavoidable distortion

• Must be chosen according to purpose

There is no distortion-free map.

There is only informed distortion.

Understanding projection is what separates a map user from a cartographer.

Next Chapter

Now that projection is defined,
we address a production-critical topic:

→ Chapter 6 — Map Generalization and Scale Control

Go to Start Page: Technology of Vector Map Production

Frequently Asked Questions

Is there a projection without distortion?
No. Every map projection introduces distortion in shape, area, distance, or direction.

Why is Mercator distorted near the poles?
Mercator preserves angles but significantly enlarges areas near the poles.

Which projection is best for world maps?
There is no universal best projection. Equal-area or compromise projections are often preferred over Mercator.

Should projection be changed mid-project?
No. Projection should be chosen at the beginning and kept consistent.

Table of contents

Chapter 1 — What Is a Vector Map?
Chapter 2 — Obtaining and Preparing Geodata (SHP, OSM, GeoJSON)
Chapter 3 — Street Network as a Graph (Nodes and Edges Explained)
Chapter 4 — Cartographic Layer Hierarchy and Visual Structure
Chapter 5 — Map Projections and Why Distortion Is Inevitable
Chapter 6 — Map Generalization and Scale Control
Chapter 7 — Vector Formats: SHP, GeoJSON, AI and PDF
Chapter 8 — Professional Map Production Workflow
Chapter 9 — Preparing a Vector Map for Print in Illustrator
Chapter 10 — Common Mistakes in Vector Map Production