地理坐标系与地图投影1

1、Map Projections and Types共四十七页CartographyThe art and science of making maps, including data compilation, layout, and design. Also concerned with the interpretation of mapped patterns. A stone tablet found in a cave in Abauntz in the Navarra region of northern Spain is believed to contain the earlies

2、t known representation of a landscape.共四十七页MapsVisual representation of the earths surface or the phenomenon (any observable occurrence) that occur on the earths surface.共四十七页Map ScaleThe degree to which a map “zooms in” on the area it is representing. Scale tells you what extent the portion of the

3、earth represented on the map has been reduced from its original size to fit on the map.共四十七页For example, 1 inch on a map may equal 10 miles in the real world. That scale might be written as 1 inch = 10 miles. Sometimes, scale is indicated as a fraction. “1/10 miles” or “1:10 miles” means 1 inch on t

4、he map equals 10 miles in the real world. 共四十七页THIS IS THE TRICKY PARTCounterintuitive part of mapping: “LARGE” OR “SMALL” scale.The more “zoomed in” the map is on an area, the larger is its map scale.large-scale map depicts a smaller areaThe less “zoomed in” the map is on an area, the smaller is it

5、s scale.Small-scale map depicts a larger area共四十七页共四十七页共四十七页Map Projections共四十七页Earth is ROUND!共四十七页So?Transforming something spherical into something flat means that the 2-D image will never exactly represent what is visible in three-dimensions. Geographers use numerous mathematical equations to pr

6、oduce map projections. 共四十七页All flat maps have some distortion in their representation of:DistanceShapeAreaOr direction. 共四十七页Types of ProjectionsEqual-area (or equivalent) projections: maps that maintain area but distort other properties.Conformal (or orthomorphic) projections: maps that maintain s

7、hape but distort other properties (it is impossible to have a projection that is both conformal and equal area).Azimuthal projections: maps that maintain direction but distort other properties.Equidistant projections: maps that maintain distance but distort other properties. 共四十七页Mercator Projection

8、Cylindrical map projectionUseful for navigation because it maintains accurate directionFamous for their distortion in area that makes landmasses at the poles appear oversized共四十七页Mercator Projection共四十七页Peters ProjectionCylindrical map projection Attempts to retain all the accurate sizes of all the

9、worlds landmassesSometimes used as a political statement- that we should refocus our attention to the tropics, home to large landmasses and many of the worlds poorest countries. 共四十七页Peters Projection共四十七页Fuller ProjectionMaintains the accurate size and shape of landmasses Completely rearranges dire

10、ction such that the four cardinal directions (north, south, east, and west) no longer have any meaning. 共四十七页Fuller Projection共四十七页Robinson ProjectionAttempts to balance several possible projection errors. Does not maintain completely accurate area, shape, distance, or direction, but it minimizes er

11、rors in each.Used by National Geographic共四十七页Robinson Projection共四十七页Azimuthal ProjectionPlanarFormed when a flat piece of paper is placed on top of the globe and, as described earlier, a light source projects the surrounding areas onto the map. Either the North Pole or South Pole is oriented at the

12、 center of the map which gives the viewer the impression of looking up or down at the earth. 共四十七页Azimuthal Projection共四十七页Map Types共四十七页Reference MapShow locations of places and geographic features.共四十七页Thematic MapTell a story about the degree of an attribute, the pattern of its distribution, or i

13、ts movement.共四十七页Thematic Map共四十七页Contour Maps (Isopleths)Isolines- Lines on a map depicting areas of same or like values. Contour maps use isolines, or contour lines, to depict where the same elevation exists.Thecontour intervalof a contour map is the difference in elevation between successive cont

14、our lines.共四十七页Contour Maps共四十七页Proportional Symbols MapThe proportional symbol technique uses symbols of different sizes to represent data associated with different areas or locations within the map.共四十七页Proportional Symbols Map共四十七页Proportional Symbols Map共四十七页A dot may be used to locate each occu

15、rrence of a phenomenon. Where appropriate, a dot may indicate any number of entities, for example, one dot for every 100 voters.Dot MapMilitary families in Ohio共四十七页Choropleth MapShows statistical data aggregated over predefined regions, such as counties or states, by coloring or shading these regio

16、ns. For example, countries with higher rates of infant mortality might appear darker on a choropleth map.共四十七页Choropleth Map共四十七页CartogramAcartogramis amapin which some thematic mapping variable is substituted for land area or distance. The geometry or space of the map is distorted in order to conve

17、y the information of this alternate variable.共四十七页Cartogram共四十七页Cartogram共四十七页Cartogram共四十七页GIS mapA geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and cha