Map Projections_Remote Sensing_Map Analysis.pptx

2-3 Maps and Map Projections What are some advantages of maps? Spatial relationships Enormous amount of information What are some limitations of maps? Impossible to present a “spherical” planet on a flat surface All flat maps are distorted 2-3 Maps and Map Projections The geographic grid has four ma...

2-3 Maps and Map Projections What are some advantages of maps? Spatial relationships Enormous amount of information What are some limitations of maps? Impossible to present a “spherical” planet on a flat surface All flat maps are distorted 2-3 Maps and Map Projections The geographic grid has four major geometric properties: 1. parallels of latitude are always parallel, 2. parallels are evenly spaced, 3. meridians of longitude converge at the poles, and 4. longitude and latitude lines cross at right angles. It is impossible to have all of these properties on the same map! 2-3 Maps and Map Projections Shape Large world regions cannot be depicted on a map without distorting either their shapes or their comparative sizes. Yet, there are map projections that depict the correct shapes of continents, regions, mountain ranges, islands, and water bodies. Maps that maintain the correct shapes of mapped areas are conformal maps. To preserve the shapes of Earth’s features, meridians and parallels on a conformal map must cross at right angles just as they do on the globe. 2-3 Maps and Map Projections Area Cartographers can create a world map that maintains correct area relationships, which means that all areas on the map have the same size proportions to each other as they have in reality. Maps with this property are called equal-area maps and should be used if size comparisons are being made between two or more areas. Equal-area maps should be also used when displaying spatial distributions. However, equal-area maps distort the shapes of mapped features because it is not possible to show both equal areas and correct shapes on the same map. 2-3 Maps and Map Projections Which kind of world map would you prefer, one that preserves area or one that preserves shape? Why? 2-3 Maps and Map Projections Map projections: any presentation of the spherical Earth on a flat surface. Planar Conic Cylindrical (Mercator) Does not display all areas accurately 2-3 Maps and Map Projections Compromise Projections Maps that compromise true shape and true area in order to display both fairly well. An interrupted projection can also reduce the distortion of landmasses by moving much of the distortion to the oceanic regions. 2-4 Remote Sensing of the Environment What is remote sensing? Remote sensing Collection of information about the environment from a distance, usually from aircraft or spacecraft photography, radar, and infrared. 2-4 Remote Sensing of the Environment Passive systems remote sensing systems that record the natural reflections or emissions of energy from a surface. Aerial photography Near-infrared (NIR) Thermal infrared (TIR) Active systems remote sensing systems that emit their own energy source and record reflected returns from surface features. Radar (radio detection and ranging) Weather radar Imaging radar 2-5 Modern Mapmaking and Analysis Geographical Information Systems (GIS) A versatile computer software/hardware system that combines the features of cartography and database management to produce maps and other displays of spatial data for solving geographic problems. What a GIS does Visually overlay images Solve problems Spatial data analysis