inches on the map. All maps also use a projection that can be formed from a developable surface and can preserve one or two properties at most. The relationship between ground and map distance can be expressed by either a linear or This type of projection would be useful visualizing airplane flight paths from one city to several other cities or in mapping an earthquake epicenter. ∠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. RF: 1: 60,000; Verbal scale: 1 in. Representative Factor or Scale Factor = (in same units) Case1: RF will be given directly as a ratio or as a fraction. How many miles to the inch when the RF = 1:24,000? Azimuthal projections preserve distance at the cost of distorting shape and area to some extent. Graphic Scale: The graphic scale is a bar chart or "ruler" that is drawn at the bottom of a topographic map. Map makers use the term scale to describe maps as being small-scale or large-scale. This equal area projection preserves area but distorts shape, but not as much as it would if it were not interrupted. Log in. 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. Graticule projected. 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. 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. More map extent and resolution. When a map is enlarged or reduced, the bar B. Graphical Scale: On a graphical scale, the units of measurement should always be stated. All other positions are specified relative to the origin, as seen with the points at (3, 2) and (-4, -1), Coordinate system. The Language of Maps, Pathway in Geography series. The graticule specifies positions on the globe with latitude and longitude coordinates. As the length on the drawing is equal to the actual length of the object, the full scale is expressed as 1:1. Mercator projection. Balancing extent and resolution is often one of the most important and difficult decisions a cartographer must make. How many km to the cm. Note that some maps may not preserve either shape or area but do a pretty good job at both. Note that distortion is not necessarily tied to the type of developable surface but rather to the way the transformation is done with that surface. The ellipses show how imaginary circles on the globe are deformed as a result of a particular projection. The roles of RF attenuators, terminations, matching pads and loads are important in radio communications test and measurement, as well as in equipment interconnection. The first we will consider is the RF or Representative Fraction. Words & Numbers Map Scale . scale changes size in direct proportion to the map. ; RF = 1: 20,000 RF = 1 500 Case 2: RF will be given not directly, Possible ways of giving RF. Gall-Peters distortion. [20]. [13]. from map units to ground units. map. For example, Greenland is only 7-percent the land area of Africa, but it appears to be just as large! is known as the scale of a map. Parts of section 3.1 are adapted from Campbell and Shin (2011). Case 1. if they are both equal in weight, compare the last 2 balls - one will be heavier. The world is vast. Essentials of Geographic Information Systems. For example, if the scale is 10 m to 1 cm, the RF of the scale is 1cm/10x100cm = 1/1000. At higher latitudes, the length of parallels decreases to zero at 90° North and South. 5 points What is RF of a scale? You can think of the extent as describing the region to which the map is zoomed. 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 E.g. As the denominator gets larger, the fraction gets smaller. B. Graphical Scale: On a graphical scale, the units of measurement should always be stated. Projection is the process of making a two-dimensional map from a three-dimensional globe. (ii) When a map is reduced or enlarged from the original, the scale does not remain the same. On equal-area projections, the size of any area on the map is in true proportion to its size on the earth. In other words, countries’ shapes may appear to be squished or stretched compared to what they look like on a globe, but their land area will be accurate relative to other land masses. Full Scale When an object is drawn on the sheet to its actual size, it is said to be drawn to full scale. Scale descriptions using the RF provide one way of considering scale, since 1:1000 is larger than 1:1,000,000. The earth’s surface has an area of over 500 million km2and any picture of the earth that you can easily carry can only show general outlines of continents and countries. Find the RF scale for the following graphic scale: By measuring with a ruler (your results may differ depending on screen resolution and size! 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. In simple terms, longitude specifies positions east and west and latitude specifies positions north and south. A good quality map should have both the RF and Bar Scales. Start studying music88nat. 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. The Gall Peters projection is equal area. The properties we will focus on are shape, area, and distance. Muehrcke, Phillip C. 1986. A conformal projection will have distortion ellipses that vary substantially in size, but are all the same circular shape. 2. Steven Manson 2017. In other words, they do not preserve shape, area, or distance, but instead try to avoid extreme distortion. Find the RF scale for the following graphic scale: By measuring with a ruler (your results may differ depending on screen resolution and size! CC BY-NC-SA 3.0. 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. Linear measurement is expressed in three ways: as a word statement, as The scale ratio is always written as one unit on the photo or map to the corresponding number of units on the ground. 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… Rf values are distance of substance from origin divided by distance of solvent front from origin. In this example, 1 centimeter on the map could equal 100,000 centimeters (1 kilometer) on Earth. How many inches to the mile when the RF = 1:24,000? Full scale: Some times the actual dimensions of the object will be adopted on the drawing then in that case it is represented by the scale and RF as Scale: - 1cm = 1cm or 1:1 and by R.F=1/1 (equal to one). 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. 1:60,000. Interrupted projections such as the interrupted Goode Homolosine projection represent the earth in lobes, reducing the amount of shape and area distortion near the poles. We often choose mapping resolutions intentionally to make the map easier to understand. The Nature of Geographic Information: An Open Geospatial Textbook. 1. Graphic Scale to RF. Map scale is represented by a representative fraction, graphic scale, or verbal description. [12]. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. It can be expressed as 1/100,000 or 1:100,000. Economies of scale can be both internal and external. Characteristics Of a Good Scale are: Map Use: Reading, Analysis, and Interpretation, The ratio of the Earth's size to the generating globe's size is called the nominal scale (= principal scale = representative fraction). The Mercator projection is conformal because it preserves shape and angle but strongly distorts area. The place where the developable surface touches the globe is known as the tangent point or tangent line. The Gall Peters projection is equal area. Some projections, including the Robinson projection, strike a balance between the different map properties. For example, if we say that the scale of a map is 1 cm : 1 km, it would be understood by only that person who is familiar with the metric system of measurement. A large scale map [3]. We use developable surfaces because they eliminate tearing, although they will produce shearing and compression. Bookmark Like 2 Dislike 0 ⚐ Report. It is possible to preserve any one of the three properties using any of the developable surfaces. Note how the shape of Greenland is significantly altered, but the size of its area is correct in comparison to other regions such as Africa. GFDL. 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. Robinson Projection. 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. As the length on the drawing is equal to the actual length of the object, the full scale is expressed as 1:1. In other words, one inch on the map is equal to one hundred thousand inches on the earth. [22]. R. F. is representation factor. Tangency. You must have seen maps with a scale bar indicating equal divisions, each marked with readings in kilometres or miles. 1 inch (in) = 2.54 centimeters 1 centimeter (cm) = 0.39 inch 1 foot (ft) = 12 inches = 30.5 centimeters = 0.3 meter 1 yard (yd) = 36 inches = 3 feet = 91.44 centimeters = 0.9 meter Interrupted distortion. Mercator projection. Join now. Representative Fraction (RF): Scale can be expressed as a ratio or representative fraction (RF). Equidistant projections, as the name suggests, preserve distance. The top image has a spatial resolution of the county and the bottom has a spatial resolution of census tracts. ), we find that 10 kilometers measures 2.4 cm. Maps showing an extent of the Pacific Northwest. Maps and the Geospatial Revolution. Reducing a 1:30,00 scale map to 50% of its orginial size changes the RF scale to The scales of maps can be compared using the RF. Full scales are … 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. This equal-area projection is interrupted in the sense that it uses lobes or sections. 8 : CONSTRUCTION:A motor car is running at a speed of 60 kph. The figure has scale bars for 1 mile, 7000 feet, and 1 kilometer. In both temperature measurements, [latex]40°[/latex] is equal to [latex]100°[/latex] minus [latex]60°[/latex]. aerial measurement. Keep in mind that all maps have a scale and there are a few important ways to indicate this scale. Take the value to find the length of the scale. Scale and projections are two fundamental features of maps that usually do not get the attention they deserve. 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. GIS Commons: An Introductory Textbook on Geographic Information Systems, CC BY-NC-SA 4.0. The resultant projections are called planar, conical, and cylindrical. Internal economies of scale are based on management decisions, while external ones have to do with outside factors. 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. 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. = = = xcm cm m cm R F. Plain scale. New York: John Wiley & Sons. A simple RF attenuator is shown in the photo below. Sizes of Scale 3. Small scale: 1 cm = 10 miles. 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. We will discuss the process of how objects on a 3-dimensional surface (the earth) come to be represented on a flat piece of paper or computer screen. ), we find that 10 kilometers measures 2.4 cm. when the RF = 24,000? One of the benefits of using a representative fraction to describe scale is that it is unit neutral. Verbal description. (2012) Mapping our Changing World. If this surface were a piece of paper that you wrapped around the globe, you could carefully trace these shadows onto the paper, then flatten out this piece of paper and have your projection! To draw a scale, need to know the “Representative Factor (RF)”. Here we must take a measurement from the bar scale to determine the map distance that corresponds to a ground distance. Enlarging a map by 200% means to make the enlarged map two times bigger than the original We can also 1992. earth. RF Group Leader; RF Group Name; RF Group Leader. These help us to visualize what type of distortion a map projection has caused, how much distortion has occurred, and where it has occurred. 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. An area of 64 sq.km is represented by 256 sq.cm on map. One of the first maps of the world developed was by Mercator (Carta do Mundo de Mercator, 1569). This is a bit misleading because no projection can maintain relative distance between all places on the map. )traveled by car in 47 minutes. RF: 1: 60,000; Verbal scale: 1 in. For example, if the scale is 10 m to 1 cm, the RF of the scale is 1cm/10x100cm = 1/1000. 2 weighings to find the slightly heavier ball. Artistic projections. If either group of 3 balls is heavier, take 2 balls from the heavier side. Scale Comparisons Consider the size of the fractions 1/100 and 1/2. No they don't. This scale can be shown as 1/100,000 or as 1:100,000. 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 For Code A and B 3 Guidelines for evaluation of section ‘B’ 1. 1991, 1996. One centimeter on the map is equal to 24000 centimeters on the surface of the earth. Paine, David P. 1981. One inch is equal to three miles (1" = 3 miles) Graphic Scale: The simplest graphic scale is a bar scale. [14]. This creates … 3. Sizes of Scale 3. Views drawn by free-hand or with drawing instruments such as plastic foot scales are to be accepted. Representative fraction and scale bars from a United States Geological Survey (USGS) topographic map. Enlarging or reducing a map is necessary for easy comparison with another map. Step 1. compare 2 groups of three balls. second edition. A printed line that has markings on it that are similar to those on a ruler. in photo equals 5,000 ft on the ground. Eric Gab Data: U.S. NGDC World Coast Line (public domain), GFDL. [16]. The simplest graphic scale is a bar scale. This topographic map has an RF of 1:24,000, which means that one unit on the map represents 24,000 units on the ground. When a 1 cm long line in a drawing represents 1 meter length of the object, 100 1 1 100 1 1 1 . For example, on the Azimuthal Equidistant projection, all points are the proportionally correct distance and direction from the center point. 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. Projections deal with the methods and challenges around turning a three-dimensional (and sort of lumpy) earth into a two-dimensional map. If the conversion process produces signals equal in amplitude and 180 deg. 1 inch (in) = 2.54 centimeters 1 centimeter (cm) = 0.39 inch 1 foot (ft) = 12 inches = 30.5 centimeters = 0.3 meter 1 yard (yd) = 36 inches = 3 feet = 91.44 centimeters = 0.9 meter Full scales are … ∠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. In the figure, the origin (0,0) is located at the center of the grid (the intersection of the two bold lines). If no distortion had occurred in projecting a map, all of the ellipses would be the same size and circular in shape. 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:. For example, it would be useful in comparing the density of Syrian refugees in the Middle East or the amount of cropland in production. Learn vocabulary, terms, and more with flashcards, games, and other study tools. This type of projection would be useful for a general purpose world map. The line represents a unit of measurement such as the kilometer or the mile. 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. The fraction 1/100 is a much much smaller number than is 1/2.

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