We explain what a graphic scale is, what it is for and various examples. In addition, the differences with a numerical scale.
What is a graphic scale?
A graphic scale is a straight graduated line, divided into equal parts. The units of the scale represent the relationship between the actual length of an object and the equivalent in drawing units.
It is usually used in maps , nautical charts, planes and other forms of spatial representation with unit by unit scale, that is, in which each unit drawn represents a set of real units of measurement. Not to be confused with the numerical scale , although both are cases of scale.
The graphic scale was first used in the Pisan Charter of the late thirteenth century , a document found in Pisa, Italy. It is a map of the seas Mediterranean, Black and part of the Atlantic Ocean. Its graphic scale appears as a circle whose radius is divided into three equal parts, each of which represents (not numerically) a distance from the map to scale.
This design has since changed to the shape of the straight line, generally located on the banks of the maps vertically or horizontally, and maritimely known as Log of leagues.
What is a graphic scale for?
The graphic scales give the person who queries a map information about the scale of his drawing. In other words, it explains how the representation is linked to the actual distances of the segment of the land surface that it describes.
You can do it without the need to resort to numbers or numerical relationships, but through a graphic or visual type convention, as established by the various cartographic sciences.
Examples of graphic scale
Graphic scale and numerical scale
Unlike the graphic scale, which represents the scale by visual proportions, a numerical scale is one that fulfills the same function , that is, to inform us how the proportions of reality have been represented on a plane or document, but Express the proportion through a set of numbers .
For example, a scale of 1:20 means that each unit of the representation equals 20 of real life, depending on the units in which they are expressed. Thus, it is common to see scales of 1 / 50,000 or 5/500, depending on how abstract the drawing is to be able to present huge objects or massive lengths, on a small screen or a paper cutout.
Both the numerical scale and the graphic scale are common in maps, plans, technical drawing works , architectural projections, etc.