Introduction

Relevance of the Theme

Cartographic Scales form the basis for understanding and interpreting the representation of the Earth's surface on maps. They are essential tools in cartography and map reading, aiding in the comprehension of real proportions and measurements of distances on the ground. Their importance is fundamental in various fields of geography, such as urban geography and physical geography, as well as in other disciplines, such as geology and architecture.

Contextualization

The study of scales is introduced after learning the concept of maps and their functions. Scales allow students to understand how the actual dimensions of the Earth's surface are represented on a piece of paper through a map and its reductions. They will be able to discern and convert different types of scales (numeric, graphic, and representational) and understand how each one affects the representation of distances on the map. This knowledge will be concretized with map reading in future classes, enabling precise location of points and understanding of spatial relationships on the Earth's surface.

Theoretical Development

DIDACTICS: The theory will be presented progressively, starting from the student's prior knowledge about the representation of the Earth on maps to the in-depth exploration of cartographic scales.

Components

• Representation of the Earth on Maps
  • Definition: Flat representation of the Earth's surface that maintains the proportion and spatial arrangement of geographical objects.
  • Cartographic Projections: Techniques for representing the Earth's surface on a plane that preserve some or all of the sphere's characteristics. Different projections have different distortions.
  • Types of Maps: Variety of maps based on specific characteristics, such as relief, climate, population, among others.
• Cartographic Scales
  • Definition: Mathematical relationship between the distances represented on the map and the corresponding distances on the Earth's surface.
  • Importance: Allows the representation of real distances and sizes of locations, objects, and geographical phenomena in a limited space.
• Types of Scales
  • Numeric Scale: Represented by a fraction, indicating the reduction of the measurement on the Earth's surface. Example: 1:100,000, where 1 unit on the map is equivalent to 100,000 units in reality.
  • Graphic Scale: Uses a graduated line to represent the relationship of distances on the map and on the surface. The segments of this line will be marked with appropriate values for reading the real distance on the terrain.
  • Representational Scale: Scales that use icons, drawings, or symbols to indicate the size of an object on the map and in reality. Widely used in tourist maps and building plans.
• Scale Conversion
  • Definition: Process of changing from one scale to another, either increasing or decreasing the representation.
  • Scale Ratios: The ratio between the distances on the map and the corresponding ones in reality. It serves as the basis for scale conversion. Example: In a scale of 1:100,000, the scale ratio is 1:100,000.

Key Terms

• Cartographic Scales: Tool that allows the reduced representation of reality.
• Scale Ratio: Mathematical relationship between distances on the map and the corresponding ones in reality.
• Map: Flat representation of the Earth or part of it.

Examples and Cases

• Use Cases of Scales
  • Urban Planning: Use of scales in maps that represent the real dimension of streets and buildings, aiding in the construction and location of urban infrastructures.
  • Reading Tourist Maps: Use of representational scales to determine the real distance between tourist attractions.
  • Understanding Proportions: Converting one scale to another demonstrates how objects and distances can be represented differently on the map, while maintaining their proportions in reality.

Detailed Summary

DIDACTICS: The summary is comprehensive, emphasizing examples and practical applications, facilitating the understanding and assimilation of the theme by students.

Key Points

• Importance of Scales:

  • Scales are fundamental for representing reality on a flat surface. They allow even extensive areas to be represented in a limited space, revealing the size and distance relationship between elements on the terrain.

• Types of Scales:

  • Different situations require different types of scales. Numeric, graphic, and representational scales are used according to the map's purpose and the information to be conveyed.

• Scale Conversion:

  • Understanding how one scale is converted to another is an essential skill. This helps to perceive how the representation of elements on a map can change without altering their proportions on the terrain.

Conclusions

• Mastery of Scales:

  • Understanding and effectively dealing with scales is a mandatory requirement for map reading and interpretation. Without adequate knowledge of scales, the information contained in a map can be misinterpreted or completely lost.

• Use of Scales in Practice:

  • The use of scales is vital in various practical situations, such as urban planning, reading tourist maps, and understanding proportions in thematic maps.

Exercises

1. Numeric Scale: Given a map with a scale of 1:50,000, separate an area of 5 cm² on paper. What will be the corresponding area on the terrain?

2. Graphic Scale: Use the graphic scale of a map that measures the distance between two lakes as 2.5 cm. Knowing that in this scale, 1 cm represents 1 km, what is the real distance between the lakes?

3. Use of Scales: Imagine a tourist map in a representational scale. The icon of a monument is 2 cm tall on the map, and the same monument is 50 meters tall in reality. If a nearby tower is 100 meters tall, what will be its height on the map?