What is a Map Scale?
Map scales are useful to understand the sizes of objects and distances between objects (their relative sizes) in comparison to the actual sizes of objects and distances between them. This means that on a map it is not possible to denote the actual distances between objects or their sizes since then the map would need to be as big as the objects being measured. This would defeat the purpose of having a map in the first place.
This is what it means when it is said that maps are drawn to scale. Scales are always mentioned on the maps so that whoever looks at them can get an idea of how to navigate through them. The scale represents how much the area on the map corresponds to the actual area on the ground that it shows. For example, if a map is drawn to a scale of one inch to one kilometre, it would mean that one inch on the map is equivalent to one kilometre on the ground.
Classification of Maps
To understand what a map scale is, let us go through a few classifications of maps and map scales first. As per the common classification of maps, there are about five types of maps - thematic maps, general maps, navigation charts, topographic maps, series maps, cadastral, and plans. The types of map scale representations are discussed below. The basic type of representation of actual distance on maps is done by bar scales and lexical scales. In the bar scales used in maps, the distance ratio is expressed visually whereas, in lexical scales, the ratio is stated in words.
There are 3 ways of representing the scale of a map, namely, representative fraction, verbal, and graphic. Out of these three, the representative fraction is the most commonly used scale. For example, the topographic maps help to understand the contour and general landforms of an area and most have the scale stated in representative fraction. In topographic maps, various colours are used to represent the contour of landforms, water bodies, settlements.
Map Projections
Map projections are used to draw the parallels and meridians of the Earth systematically, on a flat surface. Various map projections are used to represent the landforms on maps. There are certain map projections that have equal-area properties. Also, projections that have the feature of conformal delineations are devised to represent the landforms on maps.
In certain cases, the outlined shape of very small regions is nearly represented in the same way on the map as it is on the ground. It is not possible to completely avoid distortions of shapes of land areas on large-scale maps. The only way to reduce the distortions is to devise the most suitable for the purpose of the particular map.
In general, the Mercator projection is devised on the navigational charts. The charts for the polar regions and the great circle charts do not devise the ordinary Mercator projections. The Great Circle charts that represent large map areas are generally depicted on quite small scales devising gnomonic projection. For example, the navigational chart for the Pacific Ocean. The navigators use these charts to lay a track between two ports and calculate the shortest distance between the ports.
Symbolization
Symbols are the graphical representations of landforms, water bodies, winds, ocean currents, settlements, transport, and communication systems for maps. It may be said that symbols make a graphical language for maps and charts. The symbols were originally ordinary pictograms, which have now developed into conventional signs and symbols for the representation and interpretation of maps.
Standardization of symbols has been brought about by the joint efforts of the UN, NATO, International Map of the World agreements, and the international technical societies. It helped to reduce the confusion that used to arise in the interpretation of maps. The symbols can be classified as hypsographic and planimetric. These symbols can also be grouped based on conventional colours.
For example, the blue colour is used to represent water bodies, black colour is used to represent occupation, cultures, and names of population, green colour is used to depict vegetation, brown colour is used to depict relief features, and red colour is used to depict types of roads and other special information. This is the standard use of colours, but there may be variations for geologic and soil maps. Planimetric features are used to represent the slopes, heights, and shapes of the land, on a map.
Nomenclature
To enhance the utility of maps, all the possible features and places are identified and labelled on a map. However, for the small-scale maps, only the important features and places are labelled, to enhance legibility. The nomenclature of maps has various parts. The geographic names are among the most troublesome parts of map nomenclature. The large-scale maps permit the naming of the minor features like streams, hilltops, ridges, etc. While making a topographic map, extensive research and documentation are carried out.
Also, the local records are referred to for identifying and labelling all the parts of the area under concern. When a topographical map is published and distributed, it is used as an official document that eliminates confusion regarding the nomenclature of the local areas. The basic types of lettering that are used in the maps are Roman style, Italic, and Gothic style.
What is the Significance of the Map Scale?
Map scales give people an accurate idea about how the distances mentioned are plotted on the map. This is useful in understanding how to go from one place to another, especially if one is a traveller or engaged in a similar profession.
For academics, a map scale is useful to measure exact distances between objects and base their work on that. This is useful in calculating operations such as measuring the demographics of an area, measuring the geographical faults of an area, keeping a note of all physical features of the area and its vegetation, and so on. Measuring and making a note of all detailed features of an area on a map is only possible through map scales. If maps were not drawn to scale then no one would be able to navigate through an unknown place all on their own.
FAQs on Map Scales
1. How can maps be measured by scale?
Since plotting a map exactly as it is shown on the ground is not practical, maps are drawn to a certain scale. This scale is usually fixed throughout the map and also mentioned there, so people reading the map can understand what scale it is drawn to and base their findings accordingly. The scale needs to be uniformly maintained throughout the map. If the map says the scale is one centimetre to one mile, that means that one centimetre on the map is equal to one mile on the ground.
2. How accurate are map scales?
When maps are drawn to a scale, it is always specified so that the reader does not get confused by the numbers present. 1:50,000 means that one centimetre on the map is 50,000 centimetres on the ground. Map scales are meant to be extremely accurate in nature. This goes for all maps, whether they are used by travellers for sightseeing, or by cartographers for plotting minute details into them. If a map scale is inaccurate then it will throw off a lot of details about geographical descriptions.
3. What is the main distinction between small scale maps and large scale maps?
Map scales can be small scale or large scale, depending on their usage. Tourists and travellers mainly use small scale maps since their job is not to search for accuracy but to simply manoeuvre their way. In small scale maps, larger areas are shown with much less detail. They will show all geographical features, like rivers and mountains. Usually, wall maps and atlases are small scale maps. Large scale maps are mostly topographical maps. They denote every tiny detail on the map.
4. What are the benefits and drawbacks of small scale maps?
Small scale maps are great for educational and informative purposes. The distance can easily be mentioned on a linear scale in small scale maps. The map will remain geographically true if it is enlarged using technology. However, using a linear scale to understand and interpret a map is not easy, and is only known by people involved with cartography. Also, for small scale maps, the scale can only be used and understood by people who are more or less accustomed to the unit of measurement the map is drawn to.
5. What are the types of large scale maps?
Large scale maps are drawn to a particular scale and they are very detailed in nature. Interpreting large scale maps is very difficult unless the reader is associated with cartography in some way. Large scale maps are topographical maps and cadastral maps. These are detailed in nature and are generally mostly used only for research purposes. Topographical maps are used to plot every detail and every feature, be it physical or geographical, of a certain place on the map. Cadastral maps are very accurate and comprehensive maps that are used in real estate to determine properties.