Transcript cartogram
Map Projections and Types Cartography The 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 earliest known representation of a landscape. Maps Visual representation of the earth’s surface or the phenomenon (any observable occurrence) that occur on the earth’s surface. Map Scale The degree to which a map “zooms in” on the area it is representing. Scale tells you what extent the portion of the earth represented on the map has been reduced from its original size to fit on the map. 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 the map equals 10 miles in the real world. THIS IS THE TRICKY PART Counterintuitive 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 area The less “zoomed in” the map is on an area, the smaller is its scale. Small-scale map depicts a larger area Map Projections Earth is ROUND ! 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 produce map projections. All flat maps have some distortion in their representation of: Distance Shape Area Or direction. Types of Projections Equal-area (or equivalent) projections: maps that maintain area but distort other properties. Conformal (or orthomorphic) projections: maps that maintain shape 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. Mercator Projection Cylindrical map projection Useful for navigation because it maintains accurate direction Famous for their distortion in area that makes landmasses at the poles appear oversized Mercator Projection Peters Projection Cylindrical map projection Attempts to retain all the accurate sizes of all the world’s landmasses Sometimes used as a political statement- that we should refocus our attention to the tropics, home to large landmasses and many of the world’s poorest countries. Peters Projection Fuller Projection Maintains the accurate size and shape of landmasses Completely rearranges direction such that the four cardinal directions (north, south, east, and west) no longer have any meaning. Fuller Projection Robinson Projection Attempts to balance several possible projection errors. Does not maintain completely accurate area, shape, distance, or direction, but it minimizes errors in each. Used by National Geographic Robinson Projection Azimuthal Projection Planar Formed 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 center of the map which gives the viewer the impression of looking up or down at the earth. Azimuthal Projection Map Types Reference Map Show locations of places and geographic features. Thematic Map Tell a story about the degree of an attribute, the pattern of its distribution, or its movement. Thematic Map 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. The contour interval of a contour map is the difference in elevation between successive contour lines. Contour Maps Proportional Symbols Map The proportional symbol technique uses symbols of different sizes to represent data associated with different areas or locations within the map. Proportional Symbols Map Proportional Symbols Map Dot Map A dot may be used to locate each occurrence of a phenomenon. Where appropriate, a dot may indicate any number of entities, for example, one dot for every 100 voters. Military families in Ohio Choropleth Map Shows statistical data aggregated over predefined regions, such as counties or states, by coloring or shading these regions. For example, countries with higher rates of infant mortality might appear darker on a choropleth map. Choropleth Map Cartogram A cartogram is a map in which some thematic mapping variable is substituted for land area or distance. The geometry or space of the map is distorted in order to convey the information of this alternate variable. Cartogram Cartogram Cartogram GIS map A 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 charts. GIS map Location Chart Visualizations Visualizations Cognitive Map Mental map. Map drawn from memory.