Map Scale Can Be Expressed In Three Ways
- Using linear and this is known as a linear scale
- using ratio this is known as ratio fraction or RF
- using a statement where the scale is expressed in words, for example, I cm on the map represent 10 kilometers on the ground
To sum up, the map scale is just a ratio that is used to calculate the actual area or distance which is represented by the map.
So Let Me Introduce You To The Concept Of Scale And Map Scale
before understanding the map scale first you need to understand what is scale? The scale is the ratio that is used to calculate the actual size or area of items which has been reduced in size.
so why would someone want to reduce something? sometimes it is difficult to study something because it is too big or too small.
Check this video to see how the map scale looks like
for example, if you want to study bacteria it is difficult to study it with our bare eyes at its original size therefore you need to magnify it several times in order to see it. However, in order to understand the actual size of the bacteria, you will need to know how much you have magnified it in order to know the actual size of the bacteria.
if you need to study big things like let us say a country, it is difficult to study unless you reduce it in the size you can see it and the only way you can reduce it without losing the ability to calculate the actual area of original size is by using the scale.
Scale In Geography And Cartography
cartographic to problem scale
When the term scale is employed, it is contingent on the existence of a range of content-specific sub-scales. If something is said to be scale-dependent or scale-specific we can assume that there are spaces in which that phenomena flourish . While this is true, these types of statements do not suggest anything about the special nature of the scale for the phenomenon or the process. For example, Grizzly bears in the Canadian and US Rocky Mountains require vast tracts of open wilderness for survival. Habitat for the individual bears must be available at a scale appropriate to provide a source of food and security . The survival of the Rocky Mountain bear population can be considered to be at least partially scale dependant. Taking a relatively common use of scale in geography, cartographic scale, as an example, one can see that the range of scales that become possible within this single definition of scale.
When cartographic scale increases the area on Earth that can be displayed decreases, while the detail of the geography being represented can increase .
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What Are The Types Of Scale In Geography
Three Types of Scale:
- Fractional or Ratio Scale: A fractional scale map shows the fraction of an object or land feature on the map.
- Linear Scale: A linear scale shows the distance between two or more prominent landmarks.
- Verbal Scale: This type of scale use simple words to describe a prominent surface feature.
Point Scale For Normal Cylindrical Projections Of The Sphere
The key to a quantitative understanding of scale is to consider an infinitesimal element on the sphere. The figure shows a point P at latitude Ï
. Clearly the area of the ellipse increases by the same factor.
The Mercator projection maps the sphere to a rectangle by the equations
- }=\,\cos \varphi }
The calculation of the point scale in an arbitrary direction is given below.
The vertical and horizontal scales now compensate each other and in the Tissot diagram each infinitesimal circular element is distorted into an ellipse of the same area as the undistorted circles on the equator.
Graphs of scale factors
The graph shows the variation of the scale factors for the above three examples. The top plot shows the isotropic Mercator scale function: the scale on the parallel is the same as the scale on the meridian. The other plots show the meridian scale factor for the Equirectangular projection and for the Lambert equal area projection. These last two projections have a parallel scale identical to that of the Mercator plot. For the Lambert note that the parallel scale increases with latitude and the meridian scale decreases with latitude in such a way that hk=1, guaranteeing area conservation.
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Scale Variation On The Mercator Projection
The Mercator point scale is unity on the equator because it is such that the auxiliary cylinder used in its construction is tangential to the Earth at the equator. For this reason the usual projection should be called a tangent projection. The scale varies with latitude as k Ï tends to infinity as we approach the poles the Mercator map is grossly distorted at high latitudes and for this reason the projection is totally inappropriate for world maps . However, at a latitude of about 25 degrees the value of sec Ï is about 1.1 so Mercator is accurate to within 10% in a strip of width 50 degrees centred on the equator. Narrower strips are better: a strip of width 16 degrees is accurate to within 1% or 1 part in 100.
What Is A Vernier Calliper Used For
A vernier caliper is usually used to measure the diameter of circular objects. The circular jaws of the vernier caliper fits perfectly on the circumference of round objects. Vernier caliper consists of two scales, a main scale which is fixed and a moving vernier scale. The main scale has readings in millimeters.
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The Meanings Of Scale
The word scale has a few different uses related to mapping.
- Geographic scale is âscaleâ in the sense you may be used to in everyday life, referring to the general scope or extent of things. In this sense, âlarge scaleâ for example means something affecting or covering a large area, like a country or even the whole planet.
- Cartographic scale may sound backwards at first blush. In the cartographic sense, âsmall scaleâ essentially means more âzoomed outâ than large scale. Scale on a map is defined mathematically, often expressed as a representative fraction. For example, many USGS topographic maps have a scale of 1:24,000. This means that one inch on the map represents 24,000 inches in the real world. If you âzoomed inâ an inch would represent less real-world distance, say 10,000 inches thus the fraction actually becomes a larger number and the maps scale is said to be larger. Remember it this way: an area appears larger on a large scale map, and smaller on a small scale map.
- Data has scale too, in that it was collected or digitized at some resolution, which has implications for the map scale at which it can be displayed. Ideally a map should not have a larger scale than its data. For example Census data collected at the block level works well on a large scale map, but state-level data canât be extrapolated down to block level and displayed as such. Scale or resolution also applies to how detailed the actual vector or raster geometry is.
What Is Map Scale
Map scale refers to the relationship between distance on a map and the corresponding distance on the ground. For example, on a 1:100000 scale map, 1cm on the map equals 1km on the ground.
Map scale is often confused or interpreted incorrectly, perhaps because the smaller the map scale, the larger the reference number and vice versa. For example, a 1:100000 scale map is considered a larger scale than a 1:250000 scale map.
Geoscience Australia has complete ‘small scale’ reference map coverage of Australia at scales of 1:2.5, 5, 10 and 20 million. We maintain a complete national topographic map and data coverage at 1:1 million and 1:250000 scale. We have an incomplete map and data coverage at 1:100000 and 1:50000 scales. We also produce digital products for several of these categories as well as a number of themed maps.
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Large Scale And Small Scale Maps
Maps can be described by how varied the scale is.
Maps that show a large geographic area in comparison to the relative size of the map are known as small scale maps. The small scale refers to how small the fraction is.
A map showing the entire world would be considered a small scale map whereas a map showing a neighborhood would be considered a large scale map.
Small scale maps tend to show a larger geographic area and less detailed and large scale maps show a smaller geographic area with greater detail.
In the example below, the small scale map of the Chicago area shows only major transportation routes, and rivers. In the large scale map, far more detail is available such as all the streets, building footprints, street flow direction, and increased labeling of more features.
Large Versus Small Scale
Maps are described as either large scale or small scale. Large scale maps show a smaller amount of area with a greater amount of detail. The geographic extent shown on a large scale map is small. A large scaled map expressed as a representative scale would have a smaller number to the right of the ratio. For example, a large scale map could have a RF scale of 1 : 1,000. Large scale maps are typically used to show neighborhoods, a localize area, small towns, etc.
Small scale maps show a larger geographic area with few details on them. The RF scale of a small scale map would have a much larger number to the right of the colon such as 1 : 1,000,000. Small scale maps are used to show the extent of an entire country, region, or continent.
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Representing Scale On A Map
All maps will have an indicator of the scale of the map. A map that doesnt conform to a specific scale will be indicated by the words not to scale . This notations is most commonly found on graphic style maps such as the we are here or how to get here style maps used on invitations. Since GIS relies on a minimum threshold of accuracy and precision, all GIS based maps will have a scale.
There are three ways to show the scale of a map: graphic , verbal, and representative fraction. Graphic scales, also know as bar scales, as indicated by the name, show the scale graphically.
A verbal scale is text based, with the scale shown as a number and type of unit measurement equal to a specified unit measurement on the ground. The left side of the verbal is the unit of measurement on the map and the right side of the ratio is the unit measurement on the ground. For example the verbal scale, 1 = 100 means that one inch measured the the map represented 100 feet on the ground. This type of scale is sometimes confused with Representative Fraction scales.
RF scales is also a text based scale but no units are shown. The scale is a simple ratio of map to ground measurement with a colon between the two measurements . For example, a RF scale of 1 : 1,200 means that every one unit on the map is equal to 1,200 units on the ground. There is no notation of the actual unit type used on a RF scale. Therefore a RF scale of 1:1,200 is the same scale as a verbal scale of 1 = 100.
Scales In Geography: An Overview And Simple Method Of Constructing Scales
The word scale is generally used for an instrument used for drawing straight lines. But actually in Geographers language scale means the proportion or ratio between the dimensions adopted for the map and the corresponding dimensions on the ground. It can be indicated in two different ways. Example: The actual dimensions of the room say 10m x 8m cannot be adopted on the drawing. In suitable proportion the dimensions should be reduced in order to adopt conveniently on the drawing sheet. If the room is represented by a rectangle of 10cm x 8cm size on the drawing sheet that means the actual size is reduced by 100 times.
Representing scales: The proportion between the drawing and the map can be represented by two ways as follows:
a) Scale: 1cm 1m or 1cm 100cm or 1:100
b) Representative Fraction: 1/100 is the ratio between the size of the drawing and the object.
Types of Scales and their constructions:
When an unusual proportion is to be adopted and when the ready made scales are not available then the required scale is to be constructed on the drawing sheet itself. To construct the scale the data required is 1) the R.F of the scale 2) The units which it has to represent i.e. millimetres or centimetres or metres or kilometres in M.K.S or inches or feet or yards or miles in F.P.S) The maximum length which it should measure. If the maximum length is not given, some suitable length can be assumed.
R.F X maximum length the scale should measure.
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Space Place And Scale In Past And Present
Underpinning many articles in Past and Presents earliest issues is an unspoken agreement with the nation-state as container of historical process. These articles often expose this tendency within their title, including the name of the nation along with an indication of the period studied. While this tendency reflects practical intra-disciplinary divisions , it also reveals a tacit agreement that national borders delimit bounded spaces within which social and economic practices unravel.
Nonetheless, in these early issues of Past and Present, there are deviations from this pattern. The most obvious divergences occur in articles focused on the pre-national period in Europe, which refer, instead, to regional designations of space. In these articles, the focus is on the process studied, often interpreted through the lens of social class. These studies do not emphasize local meaning, but instead treat the space within which processes occur as absolute. Eric J. Hobsbawms work in this early period deserves special mention, as his work focused on social processes that crossed national borders, giving more importance to the role of class than to the national space within which it existed.
Difference Between Large Scale Map And Small Scale Map:
1. Large Scale Map: A large scale map makes every object or a landmark appear larger. Building and roads are clearly recognizable. The large scale map shows the name of malls, bridges, and the names of streets.
2. Small Scale Map: A small scale map makes objects and landmarks appear smaller. The building, road, bridge, or any land feature is not recognizable. A small scale map does not show the names of building, road, or bridge.
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Maps serve as a model of actual geographic areas. A map may be showing an area of hundreds of square miles, but the piece of paper in which it is represented is obviously much smaller. Scale in this sense is used to show an actual representation of distance. Scale is a ratio between distance on the ground and distance on the map.
There are several different types of scales that are commonly used in geography. One of them is known as “ratio scale,” or “fractional scale.” This is commonly represented by describing an area on a map as a fraction of what it represents in reality. For instance, a map may say 1:100000. That means any inch, cm, or any other unit of measurement represents 100,000 of those units on the ground.
“Linear scale” is another common method of scale. This involves a small image of a ruler showing exactly how far a mile or kilometer actually is when projected onto the map. This method is useful when calculating road distances or the distance between landmarks.
Sometimes a map uses a “verbal scale.” Somewhereusually the map’s keywill have an explanation of the scale using words. For example, it may say something like, “1 cm equals 5 kilometers.” You’ll likely find this type of scale on maps representing large distances.
M.A. from The University of Alabama
Educator since 2008
- Representing distance
An Example Of Small Scale Versus Large Scale Representation
The representation of this harbor on maps of the area is dependent on the scale of the layer used. The layer showing the counties for the entire United States shown in the image below has a very generalized coast line for this area. The is almost no detail in the coastline and the harbor is not represented at all.
The map below shows the same coastline with a layer of all counties for the state of California. While still a small scale layer, the coastline shows more detail. The Marina del Rey harbor is represented by a small inlet on the map.
In a large scale layer created to show just the County of Los Angeles boundary, the coastline for this area contains the highest level of detail, and a recognizable harbor is represented.
The examples of how the detail of a coastline changes depending on the scale of the layer helps to illustrate as well the importance of carefully considering the scale of any data used for mapping and spatial analysis. Small scale data inherently is less accurate and less detailed than large scale data. Using small scale data for large scale analysis can lead to gross errors. Data created for small scale purposes should not be used in large scale maps. Large scale data unless generalized, should not be used in small scale maps.
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