Coordinate Systems exercise session WiSe 2020/2021 Map Projections - - PowerPoint PPT Presentation
1 Coordinate Systems exercise session WiSe 2020/2021 Map Projections Sven Gedicke Institute of Geodesy and Geoinformation University of Bonn 2 - 1 Motivation map projection point on reference surface (e.g. sphere, ellipsoid) is mapped to
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Sven Gedicke Institute of Geodesy and Geoinformation University of Bonn exercise session
WiSe 2020/2021
2 - 1
map projection point on reference surface (e.g. sphere, ellipsoid) is mapped to plane
2 - 2
map projection point on reference surface (e.g. sphere, ellipsoid) is mapped to plane → different map projections cause different distortions
3 - 1
mercator projection map areas between lines of constant latitude/longitude to rectangles that preserve aspect ratios.
b a a′ b′
a b = a′ b′
3 - 2
mercator projection map areas between lines of constant latitude/longitude to rectangles that preserve aspect ratios. → angles are preserved
b a a′ b′
a b = a′ b′
→ areas are distorted (esp. close to poles)
4 - 1
cylindrical equal-area projection map areas between lines of constant latitude/longitude to rectangles of the same sizes.
b a a′ b′
ab = a′b′
4 - 2
cylindrical equal-area projection map areas between lines of constant latitude/longitude to rectangles of the same sizes. → distorted aspect ratios
b a a′ b′
ab = a′b′
→ distorted angles
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mercator projection cylindrical equal-area projection
thetruesize.com
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QGIS is a free desktop geographic information system (GIS) application for
geospatial data.
(23. September 2020)
Download: https://www.qgis.org/de/site/
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Sven Gedicke gedicke[at]igg.uni-bonn.de