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测绘工程专业英语课文翻译Unit-15Map Projection

Unit15 Map Projection(投影地图)

Map projections are attempts to portray the surface of the Earth or a portion of the Earth on a flat surface . Some distortions of conformality , distance , direction , scale, and area always result from this process . Some projections minimize distortions in some of these properties at the expense of maximizing errors in others . So m e projections are attempts to only mode rately distort all of these properties . No projection can be simultaneously conformal and area-preserving .(地图投影是在平面上描绘地球或部分地球表面的投影。保形、距离、方向、规模和地区总是有些扭曲,结果F 只读此过程。一些预测最大限度地减少这些属性的扭曲,牺牲最大限度地在别人的错误。所以我的预测是试图模式地歪曲一切这些属性。没有投影可以同时保形和保面积。)

Conformality: When the scale of a map at any point on the map is the same in any direction, the projection is conformal . Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles . Shape is preserved locally on conformal maps .(协调:当规模的地图,在地图上的任何一点在任何方向上的投影是一样的,形。经线(经线)和纬线(纬线)相交于直角。保形映射局部保持形状。)

Distance: A map is equidistant when it portrays distances from the center of the projection to any other place on the map .(距离:当地图描绘从投影中心到地图上任何其他位置的距离时,地图是等距的。)

Direction: A map preserves direction when azimuths ( angles fro m a point on a line to another point) are portrayed correctly in all directions .(方向:地图保留方向时方位角(角度从线路上的一个点到另一点)被描绘在所有方向正确。)

Scale: Scale is the relationship between a distance portrayed on a m ap and the same distance on the Earth .(尺度:尺度是一个距离的M AP和地球上的相同距离之间的关系。) Area: When a map portrays areas over the entire map so that all mapped areas have the same proportional relationship to the areas on the Earth that they represent, the m ap is anequal-area map .(区:当一个地图描绘区域在整个地图上,所有映射的区域具有相同的比例关系的地区在地球,他们表示,M AP是平等的地区地图。)

Classification of Map Projection(地图投影分类)

Map projections are generally classified into four general classes according to common properties ( cylindrical vs . conical, conformal vs . area-preserving , etc .) , although such schemes are generally not mutually exclusive .(地图投影一般分为四个一般类,根据共同的属性(圆柱比。圆锥,共形对。区域保存等),虽然这种方案属而不是相互排斥。)

Cylindrical projections result from projecting a spherical surface onto a cylinder . A cylindrical projection can be imagined in its simplest for m as a cylinder that has been wrapped around a globe at the equator . If the graticule of latitude and longitude are projected onto the cylinder and the cylinder un w rapped , then a grid-like pattern of straight lines of latitude and longitude would result . T he meridians of longitude would be equally spaced and the parallels of latitude would re main parallel but m ay not appear equally spaced any more . In reality cylindrical map projections are not so simply constructed . The three aspects of the cylindrical projections are as follows:(柱面投影是将球面投影到圆柱体上的结果。一个圆柱投影可以想象的最简单的M作为一个圆柱体已被包裹在一个地球赤道。如果经度和纬度的经纬网投影到圆柱和圆柱非W敲击,然后网格状的经度和纬度的直线模式研究ULT。经度的经度是相等的,纬度的平行度是平行的,但不会出现同样的距离。实际上柱面投影是不是那么简单的构造。圆柱投影的三个方面如下:)

●Tangent or secant to equator is termed regular , or normal . When the cylinder is tangent to the sphere contact is along a great circle (the circle formed on the surface of the Earth by a plane passing through the center of the Earth ) . In the secant case, the cylinder touches the sphere along two lines, both s m all circles ( a circle formed on the surface of the Earth by a plane not passing through the center of the Earth) .(切线或割线到赤道被称为规则,或正常。当气缸的球体接触切线沿大圆(圈形成表面的地球的飞机经过克通过地球中心。在割线的情况下,圆柱体沿两条线接触球体,两个球体都是圆的(一个在地球表面上形成的圆,而不是通过虽然地球的中心)。)

●Tangent or secant to a meridian is the transverse aspect . W hen the cylinder upon which the sphere is projected is at right angles to the poles, the cylinder and resulting projection are transverse .(子午线的切线或割线是横切面。当球体被投射的圆柱体与两极成直角时,圆柱体和由此产生的投影是横向的。)

●Tangent or secant to another point on the globe is called oblique . W hen the cylinder is at so m e other, non-orthogonal, angle with respect to the poles, the cylinder and resulting projection is oblique .(切线或割线到地球上的另一个点称为斜。当气缸在M E,非正交的,相对于极角,气缸和投影是义务神游。)

Conic projections result fro m projecting a spherical surface onto a cone . When the cone is tangent to the sphere contact is along a small circle . In the secant case , the cone touches the sphere along two lines, one a great circle, the other a small circle . In the Conical Projection the graticule is projected onto a cone tangent, or secant, to the globe along any small circle ( usually a mid-latitude parallel) . In the nor m al aspect ( which is oblique for conic projections), parallels are projected as concentric arcs of circles, and meridians are projected as straight lines radiating

at uniform angular intervals fro m the apex of the flattened cone .Conic projections are not widely used in mapping because of their relatively small zone of reasonable accuracy . The secant case , which produces two standard parallels , is more frequently used with conics . Even then , the scale of the map rapidly becomes distorted as distance from the correctly represented standard parallel increases . Because of this problem ,conic projections are best suited for maps of mid-latitude regions, especially those elongated in an east- west direction . The United States meets these qualifications and therefore is frequently mapped on conic projections .(球面投影到圆锥上的圆锥投影结果。当圆锥体与球面相切时,接触点是一个小圆圈。在割线的情况下,圆锥体接触球体翁两行,一一大圈,另一小圈。在圆锥投影的经纬网投影到圆锥切线或割线,在小绕地球(通常是一个mid-l 纬度平行)。在不平行的方面(斜向圆锥投影),平行线被投影为圆的同心圆弧,子午线被投影为直线在平锥顶点上均匀的角距,由于其相对合理的精度范围较小,圆锥映射在制图中的应用并不广泛。割线的情况下生产双标准纬线,更频繁地使用圆锥曲线。即使这样,地图的规模迅速变得扭曲,从正确的表示标准并行增加距离锿.由于这个问题,圆锥投影最适合中纬度地区的地图,特别是那些在东西方向拉长的地图。美国满足这些资格ND经常被映射在圆锥投影。)

Azimuthal ( Planar ) projections result fro m projecting a spherical surface onto a plane .When the plane is tangent to the sphere contact is at a single point on the surface of the Earth . In the secant case , the plane touches the sphere along a small circle if the plane does not pass through the center of the Earth , when it will touch along a great circle .(方位角(平面)投影是将一个球面投影到一个平面上,当平面与球面相切时,在地球表面的一个点上。在美国证券交易委员会如果飞机不穿过地球的中心,当它沿着一个大圈旋转时,飞机就会沿着一个小圆圈接触球体。)

Miscellaneous projections include unprojected ones such as rectangular latitude and longitude grids and other examples of that do not fall into the cylindrical, conic, or azimuthal categories .(杂项预测包括未计划的如矩形经纬网格和其他的例子,不落入圆柱形,圆锥形,或方位的类别。)

Choosing a projection is to deter mine: Location , Size and Shape . These three things determine where the area to be mapped falls in relation to the distortion pattern of any projection. One“traditional”rule described by Maling ( Maling , 1992 ) says:(选择一个投影是阻止我的:位置,大小和形状。这三件事决定要映射的区域与任何投影的变形模式有关。一个“传统”的规则描述的Maling(马岭,1992)说:)

A country in the tropics asks for a cylindrical projection .(热带地区的一个国家需要一个圆柱投影。)

A country in the temperate zone asks for a conical projection .(温带地区的国家要求锥形投


A polar area asks for an azimuthal projection .(极性区域要求方位投影。)

Implicit in these rules of thu m b is the fact that these global zones m ap into the areas in each projection w here distortion is lo west: Cylindricals are true at the equator and distortion increases toward the poles . Conics are true along so m e parallel so m e w here between the equator and a pole and distortion increases a w ay fro m this standard . Azimuthals are true only at their center point, but generally distortion is worst at the edge of the map . For a particular map-use the map may need to be conformal, equal area, or some compromise of these . In some cases, such as navigation , conformality is absolutely necessary . In statistical mapping , equivalence is necessary . T he final projection choice would see m to be a fairly straight forward function of minimized distortion and special properties .(在这四M B规则隐含的事实是,这些全球区M AP为每个投影在变形区罗西:cylindricals 在赤道向两极和失真的增加是真实的。圆锥曲线是真实的,我所以我在平行的赤道和极和失真增加的方式从这一标准间。azimuthals是真的只有在他们的中心点,但一般的失真是最严重的在地图的边缘。对于一个特定的地图使用的地图可能需要是共形,平等的地区,或一些妥协。在某些情况下,如导航、协调是绝对必要的。在统计映射中,等价是必要的。最后的投影选择将看到M是一个相当直的函数最小化失真和特殊属性。)

Universal Transverse Mercator (UTM)(通用横轴墨卡托投影(UTM))

Mercator projection was invented in 1569 by Gerardus Mercator ( Flanders) graphically .The properties of this projection are: (1) Conformal . (2) Meridians unequally spaced , distance increases a way fro m equator directly proportional to increasing scale . (3) Loxodromes or rhumb lines are straight . (4) Used for navigation and regions near equator .(墨卡托投影是在1569发明的赫拉尔杜斯·墨卡托(佛兰德)图形。该投影的特点是:(1)适形。(2)子午线不等距,距离增大的一种方式赤道与尺度成正比。(3)方位线或恒向线是直的。(4)用于赤道附近的导航和区域。)

The accuracy of Transverse Mercator projections quickly decreases fro m the central meridian . Therefore , it is strongly recommended to restrict the longitudinal extent of the projected region to + / - 10 degrees fro m the central meridian .(横墨卡托投影精度迅速下降,从中央子午线。因此,强烈建议限制的投影区域的纵向范围为+ / 中央子午线10度) The UTM system applies the Transverse Mercator projection to mapping the world , using 60 pre-defined standard zones to supply parameters . UTM zones are six degrees wide . Each zone exists in a North and South variant .(UTM系统采用墨卡托投影映射的世界,使用60个预先定义的标准区提供参数。UTM区六度宽。每个区域存在于北境南方变种。)