ch空間信息基礎ppt課件-展示頁
2025-05-14 12:04本頁面
【正文】 ons. 地圖投影 直接建立在球體上的 地理坐標，用經(jīng)度和緯度表達地理對象位置 建立在平面上 的直角坐標系統(tǒng)，用（ x， y）表達地理對象位置 投影 我國常用的地圖投影 1： 100萬：蘭勃特投影 （正軸等積割圓錐投影） 大部分分省圖、大多數(shù)同級比例尺也采用蘭勃投影 1： 50萬、 1： 25萬、 1： 10萬、 1： 5萬、 1： 、 1:1萬、 1： 5000采用高斯 — 克呂格投影 高斯 克呂格投影 GaussKr252。s surface in a particular area. A point on the surface of the spheroid is matched to a particular position on the surface of the earth. This point is known as the origin point of the datum. The coordinates of the origin point are fixed, and all other points are calculated from it. datam 一、地球模型 — 高程系統(tǒng) Elevation referencing 任意水準面 大地水準面 H180。s center of mass. An earthcentered, or geocentric, datum uses the earth39。s surface is defined by a sphere or spheroid. ? Although the earth is best represented by a spheroid, the earth is sometimes treated as a sphere to make mathematical calculations easier. ? The assumption that the earth is a sphere is possible for smallscale maps (smaller than 1:5,000,000). At this scale, the difference between a sphere and a spheroid is not detectable on a map. ? However, to maintain accuracy for largerscale maps (scales of 1:1,000,000 or larger), a spheroid is necessary to represent the shape of the earth. Between those
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