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The scale ratio of a 
model
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...
represents the proportional ratio of a linear dimension of the model to the same feature of the original. Examples include a 3-dimensional scale model
A scale model is a physical model which is geometrically similar to an object (known as the prototype). Scale models are generally smaller than large prototypes such as vehicles, buildings, or people; but may be larger than small prototypes ...
of a building or the scale drawings of the elevations or plans of a building.
In such cases the scale is dimensionless
A dimensionless quantity (also known as a bare quantity, pure quantity, or scalar quantity as well as quantity of dimension one) is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or 1) ...
and exact throughout the model or drawing.
The scale can be expressed in four ways: in words (a lexical scale), as a ratio, as a fraction and as a graphical (bar) scale. Thus on an architect's drawing one might read 'one centimeter to one meter', 1:100, 1/100, or . A bar scale would also normally appear on the drawing. Colon may also be substituted with a specific, slightly raised ratio symbol , ie. .
General representation
In general a representation may involve more than one scale at the same time. For example, a drawing showing a new road in elevation might use different horizontal and vertical scales. An elevation of a bridge might be annotated with arrows with a length proportional to a force loading, as in 1 cm to 1000 newtons: this is an example of a dimensional scale. A weather map at some scale may be annotated with wind arrows at a dimensional scale of 1 cm to 20 mph.In maps
Map scales require careful discussion. A town plan may be constructed as an exact scale drawing, but for larger areas amap projection
In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitud ...
is necessary and no projection can represent the Earth's surface at a uniform scale. In general the scale of a projection depends on position and direction. The variation of scale may be considerable in small scale maps which may cover the globe. In large scale maps of small areas the variation of scale may be insignificant for most purposes but it is always present. The scale of a map projection must be interpreted as a nominal scale. (The usage ''large'' and ''small'' in relation to map scales relates to their expressions as fractions. The fraction 1/10,000 used for a local map is much ''larger'' than 1/100,000,000 used for a global map. There is no fixed dividing line between small and large scales.)
Mathematics
Inmathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
, the idea of geometric scaling
Scaling may refer to:
Science and technology
Mathematics and physics
* Scaling (geometry), a linear transformation that enlarges or diminishes objects
* Scale invariance, a feature of objects or laws that do not change if scales of length, energ ...
can be generalized. The scale between two mathematical objects need not be a fixed ratio but may vary in some systematic way; this is part of mathematical projection
Projection, projections or projective may refer to:
Physics
* Projection (physics), the action/process of light, heat, or sound reflecting from a surface to another in a different direction
* The display of images by a projector
Optics, graphic ...
, which generally defines a point by point relationship between two mathematical objects. (Generally, these may be mathematical set
Set, The Set, SET or SETS may refer to:
Science, technology, and mathematics Mathematics
*Set (mathematics), a collection of elements
*Category of sets, the category whose objects and morphisms are sets and total functions, respectively
Electro ...
s and may not represent geometric objects.)
See also
* Aspect ratio *List of scale model sizes
This is a list of scale model sizes, listing a variety of size ratios for scale models.
* ResourceScale Conversion Calculator Model scales
References
{{DEFAULTSORT:List Of Scale Model Sizes
Scale model sizes
* ...
*Scale (analytical tool)
In the study of complex systems and hierarchy theory, the concept of scale refers to the combination of (1) the level of analysis (for example, analyzing the whole or a specific component of the system); and (2) the level of observation (for examp ...
*Scale invariance
In physics, mathematics and statistics, scale invariance is a feature of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor, and thus represent a universality.
The technical term ...
*Scale space
Scale-space theory is a framework for multi-scale signal representation developed by the computer vision, image processing and signal processing communities with complementary motivations from physics and biological vision. It is a formal theor ...
*Spatial scale
Spatial scale is a specific application of the term scale for describing or categorizing (e.g. into orders of magnitude) the size of a space (hence ''spatial''), or the extent of it at which a phenomenon or process occurs.
For instance, in phy ...
References
{{Fractions and ratios fr:Échelle it:Scala di rappresentazione