8 : CONSTRUCTION:A motor car is running at a speed of 60 kph. There are hundreds of projections, each which distorts the world in a slightly different way. All other positions are specified relative to the origin, as seen with the points at (3, 2) and (-4, -1), Coordinate system. [6]. Gersmehl, Phil. Scale and projections are two fundamental features of maps that usually do not get the attention they deserve. When using a verbal scale, numbers are often rounded to get a more desirable result. The object with the larger mass of the two, or three or however much will have the greater or greatest momentum, because there is an inverse relationship between the momentum of an object and its mass. Artistic projections. The fraction 1/100 is a much much smaller number than is 1/2. Step 1. compare 2 groups of three balls. A conformal projection will have distortion ellipses that vary substantially in size, but are all the same circular shape. The roles of RF attenuators, terminations, matching pads and loads are important in radio communications test and measurement, as well as in equipment interconnection. 3. … Red lines or dots mark the tangent line or point respectively. Words & Numbers Map Scale . Some maps, especially older ones, use a verbal description of scale. When a map is enlarged or reduced, the bar scale changes size in direct proportion to the map. To find the actual distance you first measure the distance between the two points on the map and then you compare that measurement with the map scale. It is helpful to think about projections in physical terms. There are also many projections that are aesthetically pleasing, but not intended for navigation between places or to visualize data. Representative fraction (R.F.) The numerator, which is always set to one (i.e., 1), denotes map distance and the denominator denotes ground or “real-world” distance. The figure has scale bars for 1 mile, 7000 feet, and 1 kilometer. This is a bit misleading because no projection can maintain relative distance between all places on the map. One way of looking at the problem is with distortion ellipses. Case 1. if they are both equal in weight, compare the last 2 balls - one will be heavier. The term “map projection” refers to both the process and product of transforming spatial coordinates on a three-dimensional sphere to a two-dimensional plane. If you had a clear globe the size of a beach ball and placed a light inside this globe, it would cast shadows onto a surrounding surface. Auto Mode—In this mode, the members of an RF group elect an RF group leader to maintain a primary power and channel scheme for the group. [19]. With the numerator always set to 1, the denominator represents how much greater the distance is in the world. If suppose you have 1 km of length on land and you chose to represent it on a map its is necessary to reduce it by some factor. By the end of this chapter, you should be able to read map scales and identify common projections along with their basic features and uses. This is the scale that you should use when asked to measure distances on the map. )traveled by car in 47 minutes. We can also A ratio or representative fraction (RF) indicates how many units on Earth's surface are equal to one unit on the map. Representative fraction scale (RF): Two other terms refer to the representative fraction scale - the fractional scale and the RF scale which is the scale ratio written in fractional form, 1/20,000. [18]. Internal economies of scale are based on management decisions, while external ones have to do with outside factors. These surfaces can be a (a) cylinder, (b) cone, or (c) plane. Adapted from Dibiase et al. One important advantage of graphic scales is that they remain true when maps are shrunk or magnified. Some AC voltmeters come equipped with a dBm range or scale (sometimes labeled “DB”) intended for use in measuring AC signal power across a 600 Ω load. The graticule specifies positions on the globe with latitude and longitude coordinates. [9]. Log in. When we use longitude and latitude on a two-dimensional map, we refer to these as geographic coordinates. Obviously, for full scale, RF = 1. The extent of the map below is national as it encompasses the contiguous United States, while the resolution is the state, because states are the finest level of spatial detail that we can see. Map resolution and extent. Instead, cartographers use projections to create useable two-dimensional maps. The point at which both x and y equal zero is called the origin of the coordinate system. Most projections transform part of the globe to one of three “developable” surfaces, so called because they are flat or can be made flat: plane, cone, and cylinder. In reality, it is more of an ellipsoid with a few bulges, but it is fine to think of it as a sphere. The figure below offers two more examples of the difference between extent and resolution. Adapted from J. Campbell and M. Shin (2012). ), we find that 10 kilometers measures 2.4 cm. Note that some maps may not preserve either shape or area but do a pretty good job at both. Projection is the term for turning a three-dimensional globe into a two-dimensional map. The representative fraction (RF) describes scale as a simple ratio. Areal measurement most often is algebraically adding two sine wave voltages of equal amplitude which are not harmonically related, e.g., 800 Hz and 1.8 kHz. Representative fraction. [1]. 2. [5]. covers a small area while a small scale map covers a large area. This type of projection would be useful for a general purpose world map. second edition. COMPARATIVE SCALE: length of scale = RF X 60 km = 1 / 4,00,000 X 60 X 105 = 15 cm.EXAMPLE NO. The scales of maps can be compared using the RF. Due the fact that the solvent front is always larger from the distance travelled by the solute, Rf values are always between 0 - one extreme where solute remains fixed at its origin and 1 - the other extreme where the solute is so soluble that it moves as far as the solvent. Geography. When we visually represent a region of the world on a map, we must reduce its size to fit within the boundaries of the map. Cartographers face these three issues of shearing, tearing, and compression on a globe when they try to transform the three-dimensional globe into a two-dimensional map. 8 : CONSTRUCTION:A motor car is running at a speed of 60 kph. As you peel and flatten the skin, you will encounter several problems: Cartographers face the same three issues when they try to transform the three-dimensional globe into a two-dimensional map. Scale refers to how map units relate to real-world units. An RF of            from map units to ground units. Construct a Diagonal scale of RF = 3:200 (i.e. Gall-Peters projection. Chief Directorate: Spatial Planning & Information, Department of Land Affairs, Eastern Cape. The scale should measure up to 6 meters. Kindly provide the complete solution of above question. You can think of the extent as describing the region to which the map is zoomed. Map scales. A RF SCALE IS A REPRESENTATIVE FRACTION SCALE. Madison, Wisconsin: JP Publications. to twenty thousand". RF scale is simply the units of land represented on a map. Mercator projection. For example, a scale of 1:24,000 indicates that every unit measured on the map represents 24,000 of those same units on the earth. "The larger the number, the smaller the scale" sounds confusing, but it is easy to understand. Goode homolosine projection of the world. Steven Manson 2017. As we can see with an equal-area projection, however, the ellipses maintain the correct proportions in the sizes of areas on the globe but that their shapes are distorted. Indiana, Pennsylvania: National Council for Geographic Education. [8]. A word statement is a descriptive scale and usually is expressed in different units, One inch is equal to three miles RF Group Leader; RF Group Name; RF Group Leader. 1. All maps also use a projection that can be formed from a developable surface and can preserve one or two properties at most. As we see below, however, there are times when you can create maps with tearing and they are quite useful. Equidistant projections, as the name suggests, preserve distance. This is an BNC-type attenuator. [13]. SOLUTION STEPS: Scale of km. This scale can be shown as 1/100,000 or as 1:100,000. The first unit is subdivided into smaller parts. Thinking of projections in physical terms. In other words, one inch on the map is equal to one hundred thousand inches on the earth. The representative fraction is accurate regardless of which units are used; the RF can be measured as 1 centimeter to 24,000 centimeters, one inch to 24,000 inches, or any other unit. 1:66 2/3) showing meters, decimeters and centimeters. The Representative Factor (R.F) of scale is? out of phase, the image rejection will be theoretically infinite. New York: John Wiley & Sons. inches on the map. With the strength and applied loads expressed in the same units, the Reserve Factor is defined in one of two ways, depending on the industry: RF = proof strength / proof load RF = ultimate strength / ultimate load Instead of the two linear measurement scales x and y, as with a Cartesian grid, the geographic coordinate system uses an east-west scale, called longitude that ranges from +180° to -180°. The properties we will focus on are shape, area, and distance. Projections must distort features on the surface of the globe during the process of making them flat because projection involves shearing, tearing, and compression. [2]. When we talk about large- and small-scale maps and geographic data, then, we are talking about the relative sizes and levels of detail of the features represented in the data. A map of an area 100 miles long by 100 miles wide drawn at a scale of 1:63,360 would be more than 8 Scale Comparisons Consider the size of the fractions 1/100 and 1/2. For example, in the Gall-Peters projection, the shape of Greenland is significantly altered, but the size of its area is correct in comparison to Africa. The consistent shapes indicate that conformal projections (like this Mercator projection of the world) preserve shapes and angles. The north-south scale, called latitude, ranges from +90° (or 90° N) at the North pole to -90° (or 90° S) at the South pole. They are very useful for navigation, topography (elevation), and weather maps. Characteristics Of a Good Scale are: GNU Free Documentation License, Version 1.2. Starting in the 7.0.116.0 release, the RF Group Leader can be configured in two ways as follows: . How many cm to the km. One of the benefits of using a representative fraction to describe scale is that it is unit neutral. Here such a scale means that one unit of measurment on the map is equal to 50000 of the same unit on the ground. Equidistant maps are able, however, to preserve distances along a few clearly specified lines. It is for this reason that cylinders are often used for areas near the equator, cones used to map the mid-latitudes, and planes used for polar regions. Or it is also called Scale factor. 1991, 1996. These divisions are used to find out the ground distance on the map. The graticule is based on an east-west scale called longitude and a north-south scale called latitude. Some projections, including the Robinson projection, strike a balance between the different map properties. Representative fraction and scale bars from a United States Geological Survey (USGS) topographic map. Secondary School. We often choose mapping resolutions intentionally to make the map easier to understand. The reduction of an area A verbal scale or word scale uses a word statement to explain the scale; for example, "1 inch equals 1 mile" means that 1 inch on the map will equal 1 mile in reality. If you had a globe made of paper, you could carefully try to ‘peel’ it into a flat piece of paper, but you would have a big mess on your hands. ... denominator of the fractional scale to get actual distance Step 3: Convert your calculated distance to a useful unit We have a map with scale 1:50000 We measure a distance on the map of In this example, 1 centimeter on the map could equal 100,000 centimeters (1 kilometer) on Earth. This is the scale that you should use when asked to measure distances on the map. In terms of actual mechanics, most projections use mathematical functions that take as inputs locations on the sphere and translate them into locations on a two-dimensional surface. Converting Between Scale Types of Historic and Modern Maps, page 3 Converting Representative Fraction (RF)/Ratio Scale to Lexical Scale English and Metric Measures of Length to use:. Map Use: Reading, Analysis, and Interpretation, Full scales are … 3. RF + EMF Unit Conversion Charts: Concerned about their Radio Frequency exposure levels and EMF exposure levels? The earth’s surface has an area of over 500 million km2 and any picture of the earth that you can easily carry can only show general outlines of continents and countries. The numerator, which is always set to one (i.e., 1), denotes map distance and the denominator denotes ground or “real-world” distance. A Cartesian coordinate system, like the one below, is simply a grid formed by putting together two measurement scales, one horizontal (x) and one vertical (y). In other words, instead of preserving shape, area, or distance, they try to avoid extreme distortion of any of these properties. Graphic Scale: The graphic scale is a bar chart or "ruler" that is drawn at the bottom of a topographic map. E.g. The second distinct concept of scale applies to the variation in scale across a map. The Interrupted Goode Homolosine preserves area (so it is equal-area or equivalent) but does not preserve shape (it is not conformal). A simple RF attenuator is shown in the photo below. Be the first to answer this Question ! [7]. Thus, while a degree of longitude at the equator is equal to a distance of about 111 kilometers, that distance decreases to zero at the poles. Map scale measures how much the features of the world are reduced to fit on a map; or more precisely, map scale shows the proportion of a given distance on a map to the corresponding distance on the gro… Keep in mind that all maps have a scale and there are a few important ways to indicate this scale. 3. Compromise distortion. … map. Shearing, tearing, compression. More map extent and resolution. For Code A and B 3 Guidelines for evaluation of section ‘B’ 1. Adapted from Sutton, O. Dassau, M. Sutton (2009). The representative fraction (RF) describes scale as a simple ratio. to twenty thousand". When a map is enlarged or reduced, the bar When we visually represent a region of the world on a map, we must reduce its size to fit within the boundaries of the map. A 3-meter by 5-meter map of the United States has a small map scale while a UMN campus map of the same size is large-scale. Put differently, if we were to change the scale of the map with an RF of 1:100,000 so that a section of road was reduced from one unit to, say, 0.1 units in length, we would have created a smaller-scale map whose representative fraction is 1:1,000,000. Here we must take a measurement from the bar scale to determine the map distance that corresponds to a ground distance. Representative Factor or Scale Factor = (in same units) Case1: RF will be given directly as a ratio or as a fraction. [3]. Representative fraction scale (RF): Two other terms refer to the representative fraction scale - the fractional scale and the RF scale which is the scale ratio written in fractional form, 1/20,000. You can conceptualize projection as working with a clear globe, a light bulb, and tracing paper. R. F. is representation factor. The geographic coordinate system is designed specifically to define positions on the Earth’s roughly-spherical surface. Image-rejection mixers direct the RF signal above the LO to one IF port and direct its image (RF signal below the LO) to the other IF port. ; RF = 1: 20,000 RF = 1 500 Case 2: RF will be given not directly, Possible ways of giving RF. The top image has a spatial resolution of the county and the bottom has a spatial resolution of census tracts. The graticule refers to longitude and latitude on a three-dimensional globe. To effectively use maps you need to convert measurements 1992. The fraction 1/100 is a much much smaller number than is 1/2. CC BY-NC-SA 4.0. Rf values are distance of substance from origin divided by distance of solvent front from origin. In other words, a map scale provides the relationship between the map and the whole or a part of the earth’s surface shown on it. In other words, they do not preserve shape, area, or distance, but instead try to avoid extreme distortion. Safe Living Technologies Inc. has created a RF unit conversion table and EMF unit conversion table: Some projections, including the Robinson projection, strike a balance between the different map properties. CC BY-NC-SA 3.0. Essentials of Geographic Information Systems. Projections deal with the methods and challenges around turning a three-dimensional (and sort of lumpy) earth into a two-dimensional map. scale changes size in direct proportion to the map. Essentials of Geographic Information Systems, The Nature of Geographic Information: An Open Geospatial Textbook, https://2012books.lardbucket.org/books/geographic-information-system-basics/index.html, https://www.e-education.psu.edu/geog160/node/1914, https://www.e-education.psu.edu/maps/l1_p5.html, http://docs.qgis.org/2.14/en/docs/gentle_gis_introduction/introducing_gis.html, http://nationalatlas.gov/articles/mapping/a_projections.html, https://commons.wikimedia.org/w/index.php?curid=16115307, https://commons.wikimedia.org/w/index.php?curid=730484, https://commons.wikimedia.org/w/index.php?curid=24628, https://commons.wikimedia.org/w/index.php?curid=16115242, https://commons.wikimedia.org/w/index.php?curid=12052919, https://commons.wikimedia.org/w/index.php?curid=16115152, https://commons.wikimedia.org/w/index.php?curid=12835427, https://commons.wikimedia.org/w/index.php?curid=16115337, https://commons.wikimedia.org/w/index.php?curid=4256, https://commons.wikimedia.org/w/index.php?curid=16115269, https://commons.wikimedia.org/w/index.php?curid=24727413, https://commons.wikimedia.org/w/index.php?curid=16115372, https://commons.wikimedia.org/w/index.php?curid=167921, Creative Commons Attribution-NonCommercial 4.0 International License, Scale and ways of telling the map user what the map is measuring on the ground, Projection mechanics, types of projections, and their characteristics, Shearing – stretching the skin in one or more directions, Compressing – forcing the skin to bunch up and condense, CC BY-SA 3.0. Aerial Photography and Image Interpretation for Resource Many projections are interesting and beautiful, like this Stabius-Werner Projection, but are not intended for navigation between places or to visualize data. [4], Locations on the earth’s surface are measured in terms of coordinates, a set of two or more numbers that specifies a location in relation to some reference system. Longitude and latitude. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 3. Maps can have an enormous array of different coordinate systems depending on who developed and used them. The world is vast. [10]. Obviously, for full scale, RF = 1. The most commonly used measure of map scale is the representative fraction (RF), where map scale is shown as a ratio. For example, if the scale is 10 m to 1 cm, the RF of the scale is 1cm/10x100cm = 1/1000. As noted above, the graticule on a globe is helpful, but how do we go from three-dimensional graticule to two-dimensional geographic coordinates, as per the figure below? It is possible to preserve any one of the three properties using any of the developable surfaces. Converting Between Scale Types of Historic and Modern Maps, page 3 Converting Representative Fraction (RF)/Ratio Scale to Lexical Scale English and Metric Measures of Length to use:. when the RF = 24,000? The solute can never travel farther than the solvent, so the final ratio will always be less than or equal to one. You must have seen maps with a scale bar indicating equal divisions, each marked with readings in kilometres or miles. For example, it would be useful in comparing the density of Syrian refugees in the Middle East or the amount of cropland in production. For beginning mapmakers, understanding the exact mechanics of projections doesn’t matter as much as knowing which map properties are maintained or lost with the choice of projection – the topic of the next section. case 2. Starting in the 7.0.116.0 release, the RF Group Leader can be configured in two ways as follows: . This creates … Conformal projections preserve shape and angle, but strongly distort area in the process. 2 weighings to find the slightly heavier ball. Many maps state the nominal scale and may even display a bar scale (sometimes merely called a 'scale') to represent it. Log in. aerial measurement. Graphic Scale to RF. Put differently, if we were to change the scale of the map with an RF of 1:100,000 so that a section of road was reduced from one unit to, say, 0.1 units in length, we would have created a smaller-scale map whose representative fraction is 1:1,000,000. Rf values are distance of substance from origin divided by distance of solvent front from origin. For example, with the Mercator projection, the shapes of coastlines are accurate on all parts of the map, but countries near the poles appear much larger relative to countries near the equator than they actually are. Small scale: 1 cm = 10 miles. 1:50000 can be shown as 1/50000 as well. RF Measurement Concepts F. Caspers 1 and P. Kowina 2 1 CERN, Geneva, Switzerland 2 GSI, Darmstadt, Germany Abstract For the characterization of components, systems and signal s in the radiofre-quency (RF) and microwave ranges, several dedicated instru ments are in use. It can be expressed as 1/100,000 or 1:100,000. The first we will consider is the RF or Representative Fraction. You must have seen maps with a scale bar indicating equal divisions, each marked with readings in kilometres or miles. Compromise projections preserve no one property but instead seek a compromise that minimizes distortion of all kinds, as with the Robinson projection, which is often used for small-scale thematic maps of the world. Map scale is represented by a representative fraction, graphic scale, or verbal description. (1" = 3 miles). The resultant projections are called planar, conical, and cylindrical. This type of projection is important for quantitative thematic data, especially in mapping density (an attribute over an area). A large scale map shows limited distance, but is able to show more detail. Fundamentals of Remote Sensing and • Divide the first part A0 into 10 equal … Management. It simply means that 1 unit on the mapis to 100,000 unitson the earth's surface. Mercator distortion. B. Graphical Scale: On a graphical scale, the units of measurement should always be stated. The simplest system of this kind is a Cartesian coordinate system, named for the 17th century mathematician and philosopher René Descartes. Azimuthal projections preserve distance at the cost of distorting shape and area to some extent. Map scale measures how much the features of the world are reduced to fit on a map; or more precisely, map scale shows the proportion of a given distance on a map to the corresponding distance on the ground in the real world. Representative fraction (RF) or natural scale. Adapted from Michael Schmandt (nd). Temperature scales like Celsius (C) and Fahrenheit (F) are measured by using the interval scale. We use developable surfaces because they eliminate tearing, although they will produce shearing and compression. ), we find that 10 kilometers measures 2.4 cm. Scale bars are graphical representations of distance on a map. COMPARATIVE SCALE: length of scale = RF X 60 km = 1 / 4,00,000 X 60 X 105 = 15 cm.EXAMPLE NO. If no distortion had occurred in projecting a map, all of the ellipses would be the same size and circular in shape. Asked by: Vishal on Jan 2, 2016. Full Scale When an object is drawn on the sheet to its actual size, it is said to be drawn to full scale. Muehrcke, Phillip C. 1986. The flat surface touches the globe and it is the point on the projected map which has the least distortion. Maps will most accurately represent objects on the globe at these tangent points or lines, with distortion increasing as you move farther away due to shearing and compression. 1. It is always equal to 1 The denominator represents ground distance in the same units as the numerator. These divisions are used to find out the ground distance on the map. ∠oa ∠PA 60000' 1' 60000' 12" = = = H f s Scale of a Vertical Aerial Photograph Over Variable Terrain h is the measurement of the elevation of a point above the sea level and the H is the altitude above sea level. Representative Fraction (RF) This is a unit-less fraction used to express the ratio of map distance to earth distance. 1:60,000. This equal-area projection is interrupted in the sense that it uses lobes or sections. Conformal projections should be used if the main purpose of the map involves measuring angles or representing the shapes of features. In this chapter, we have explored the concepts of scale, resolution, and projection. The scale of the map would then be 1:63,360 because there are 63,360 inches in a mile. (2012) Mapping our Changing World. For example, it is common to see “one inch represents one kilometer” or something similar written on a map to give map users an idea of the scale of the map. Verbal map scale: A map scale that expresses the relationship between distance on the map and distance on the ground in words; for example, "One inch equals 10 miles." (2012) Mapping our Changing World. An area of 64 sq.km is represented by 256 sq.cm on map. For example, if the scale is 10 m to 1 cm, the RF of the scale is 1cm/10x100cm = 1/1000. This description of map scale as large or small can seem counter-intuitive at first. Since no projection can preserve all properties, it is up to the map maker to know which properties are most important for their purpose and to choose an appropriate projection.

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