Projection Distortion

Each of the red blobs in the map below would,  on a globe or in the real world, occupy the same amount of space (area) and be the same shape (a circle).Tissot error elipses on an unprojected lat-long world map

Tissot error elipses on an unprojected lat-long world map

tissot.zip: A tissot shapefile in geographic decimal degrees you can load into your gis to demonstrate distortion in whatever projection you like.

A really useful enhancement would be to change generate_tissot.py to generate more and smaller tissot circles for smaller localised projections like UTM. [hint hint]

The script and graphic is courtesy of Matt Perry in Examining the distortion of map projections, which has more examples and explanation.