Kartographie 10

-graticule: a graph (grid) imposed on earth to specify locations

-planar geometry (flat 2D surface): easy mathms, but great distortions, good for small areas

-sperical geometry (curved 2D surface): minimal distortion, but more difficult maths, good for larger areas

-measurements units: planar: metrics, imperial; angular: degrees

-geodesy: shape & size of the earth: size: circumference: 40 075km;

shape: prolate vs oblate speroid, geoid, datums, reference ellipsoid

earth's coordinate system, ch landesvermessung,universal mercator system (UTM)

graticule: longitude/latitude

geometry: sperical

coverage: global

sexagesimal system: 1°= 60' (minutes) = 60'' (seconds)

reference lines: equator and prime meridian (greenwich)

latitude: parallel to äq., 90° N/S

longitude: 180°E/W

äq. + all meridians are great circles

lenght of latitude: 1°= 110km= 69 miles; x= cosinus of x * lenght of Equator

length of longitude: 1°= 111 km= 96 miles; x= cosinus of (x° lat.) * lenght of Equator

geometry: planar

coverage: switzerland

units: metrics

reference ellipsoid: Bessel 1841

position &orientation base: Alte Sternwarte Bern; origin E 600 000m, N: 200 000 m

in meters from origin: called easting, northings

control point network: LV 03, LV 95

notation always positive: 500 000 m east; 100 000 m north

permament recording

geometry: planar, minimize distortion with stripes

coverage: narrow stripes arround globe from pole to pole, use for gps, army, easy

units: metrics

U-niversal: global, not for other planets

T-ransverse: the cylinder is rotated 90° alligning a cental meridian rather then the equator

M-ercator: flemish cartographer

developed in US army

coverage: 60 stripes (zones) arround entire globe oriented north /south; W>E from the international data line

6 DEG wide?

2 false origins (N/S) and a central meridian, locations measured in meters( eastings/northings) from origin, always positive, encreasi towards east/north

map projection: process to flatten out the globe out the globe

approximations, transformations (alway include distortion)

examples of azimuthal perspective projection;

- orthographic (light source infinitely)

-stereographic (light source at opposite side of the sphere)

-gnomonic projections (centrally located light source; special properties : great circles and lines)

-> distortions increase from standard point or line

definition: series of mathematical coordinate transformations

earth geoid / reference ellipsoid

infinite number of map projections possible;there's no best projection, only best matched one

map projections characteristics:

class: plane, cone, cylinder

case: tangent, secant

aspect: equatorial, oblique, polar

distortion: angle,area, distance, direction

types: preserving metric, perspectiove projections, projection by surface, compromise projections

three common map projection classes:

-plane: projection onto a flat piece of paper (azimuthal projection class)

tangent location is a pont (on hte sphere) or standard line (cut though sphere)

e.g. tangent at a pole, mid-latitude or eq.

example: Azimuthal-Equidistance

-cylinder: projection onto a paper cylinder (cylindric projection class)

tangent at one or more lins:standard lines, most common one: eq.

distortion increases away from tangent, distortion based on: area, angle, distance, direction

example: mercator

-cone: projection onto a paper cone (conic projection class)

tangent: sone or more standard lines

ideal for mapping continents

distortion increases away from tangent, can be varied to preserce angle, distance, area or direction

example: lambert equal area conic

inevitable consequence

scale factor= local scale/ principal scale

paper touches globe along a line-> tangent

paper cuts globe globe along a line -> secant

different surface projections create different distortions

you cannot preserve attributes (area, angle/ shapes, distances, directions) at the same time!

distortion is greater in smaller scales (larger areas)

3 distortion types:

-area: equivalence

-angles: conformality

-distance: equidistance