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| == Map and projection basics == geoid ???? take slides from cartography exercise some words Tissot's Indicatrix Geodetic datum and coordinate transformations |
== [[MapBasics | Map and projection basics]] == |
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| === Projections === {{attachment:tmerc.png||height="370px",width="494px"}} {{attachment:nplaea.png||height="370px"}} {{attachment:vandg.png||height="370px"}} {{attachment:sinu.png||height="370px"}} {{attachment:tmerc_tissot.png||height="370px",width="494px"}} Example conformal map {{attachment:nplaea_tissot.png||height="370px"}} Example equal area map |
Visualising spatial data
High level programming languages like e.g. Python, Matlab, R, IDL allow for the easy generation of maps by using specific modules. Alternatives to produce maps is special commerical or non-commercial software like e.g. ArcGIS, Generic mapping tool (GMT), ...
[[MapBasics | Map and projection basics]]
How to do it in Python
There are different ways to generate maps with geographic information within Python. These are either based on the PyNGL (Gallery) or Basemap packages. PyNGL is very flexible to handle and allows for the generation of high quality maps. However, it takes a while to generate a nice looking map in PyNGL. If you just want to visualise your data, Basemap might be a very good alternative in many cases.
Define projection
The first step is the generation of an Basemap object which includes also the definition of the projection. Which projection to choose depends on your application. You might want to have a map with specific properties like e.g. equal area or equal angular and optimized for a specific region like e.g. the polar regions.
??? generate all maps with Tissots indicatrix ???
Load some vector data
References:
- Snyder: Map projections - a reference manual