ECON 370 1st Edition Lecture 2 Outline of Last Lecture I. What is a map?a. Defining the mapb. Reference versus thematic mappingc. All maps lieII. But what makes a map a map? MapicityIII. What is cartography?: cartographic dichotomies Outline of Current Lecture II. Map ProjectionsIII. Map projection mechanicsIV. Map projection distortionsCurrent Lecture- Map projections: from a round earth to aflat mapo Background: geodesy and thegeographic coordinate system Geodesy: the science andpractice of earthmeasurement, with thegoal of accurately/preciselydescribing the surface ofthe earth - Geoid: magneticsphere of earth- No necessary information but good background to know  Coordinate system: a system of units used to specify locations on a description of the earth - Geographic coordinate system: a system of specifying locations onthe earth (i.e., a coordinate system) that is based on principles of spherical geometry- If not familiar with this, read chapter 7These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Geographic coordinates (2):- Latitude: the angular distance (in degrees) of a position on the earth north or south of the equatoro A line of latitude is called a parallel, as it does not intersectany other lines of latitude Approximately equal spaced   Parallels run east/west  Parallels are measured in north/south- Longitude: the angular distance (in degrees) of a position on the earth east or west of a fixed origin (the prime meridian)o A line of longitude is called a meridian, with all meridiansintersecting at both the north andsouth poles   The distance of 1 degreelongitude depends on thelatitude o Meridians run north/southo Meridians are measured east/westo Measuring longitude with an chronometer   15 degrees longitude equates to one hour of time (360 degrees/24 hours = 15 degrees/hour) Graticule: the coordinate system imposed on the earth based on the network of meridians and parallels - Great circles: the shortest distance betweentwo points on earth  o The route produced by a plane thatintersects the two points of interestand the center of the earth o All meridians are great circleso The only parallel that is a great circle is the equator - Rhumb lines/loxodromes: a line of constant bearing or direction between two points on earth o Map projections: the basics  Map projection: a translation from a 3Ddescription of the earth to a 2D maprepresentation of the earth - Translation facilitated bygeographic coordinates and thegraticule  Reference globe: the description of theearth that is reduced down to the scale ofthe map page Developable surface: the flat surface ontowhich the reference globe is translated General ways to characterize map projections (2):- Mechanics: variation in the process of translating the reference globe to the developable surfaceo Altogether described as the projection parameters - Outcome: variation in the map properties that are either maintained or distorted as a result of the translationo Altogether described as the projection parameters o Map projection mechanics Class - Class: the shape of the developable surface onto which the reference glove is projected  Primary classes of developable surfaces (4):- Cylindrical: a map projection with a developable surface shaped like a cylinder, with the cylinder then unrolled to produce the mapo Resulting map looks rectangularo Parallels appear horizontallyo Meridians appear vertically Primarily good for navigation, as all straight lines are #rhumblines  Mercator is common to web mapping services because of the rectangular appearance of the graticule - Conic: a map projection with a developable surface shaped like a cone, with the cone then unrolled to produce the mapo Resulting map looks semi-circularo The cone point itself is removed due to the large levels of distortiono Parallels: ends curve in the direction of the cone pointo Meridians: appear straight and radiate out from the cone point- Planar: a map projection with a developable surface shaped like a flat plane (i.e., the map is the developable surface)o Resulting map looks circularo All planar projections are #azimuthalo Parallels appear as concentric circleso Meridians appear straight and radiate out from center - Mathematical: the translation of geographic coordinates from reference globe to map is determined by a mathematical function  Case:- Case: the way in which the developable surface intersects the reference globe- Primary cases of developable surface (2):o Tangent: a map projection with a developable surface that rests on top of the reference globe o Secant: a map projection with a developable surface that slices through the reference globe - Secant projections distort the map less overall because they have an additional standard line, or have a single standard line instead of a standard point- Cartographic scale: the ratio between distance measurements on the map and distance measurements on the earth - Standard line/point: the location(s) on the map where the reference globe and the developable surface tough o Cartographic scale is only accurate at standard lines/points Where the scale factor is equal to one (map scale atthe given location is equal to the reported map scale, SF=1) Therefore, distance is distorted everywhere but thestandard