Chapter 3

Scale and Projection

Chapter 3 explores geographical thinking and giscience perspectives on scale. Thinking about cartographic scale inevitably demands exploration of map projections, which are also considered.

Links for Chapter 3

Lewis Carroll’s Sylvie and Bruno Concluded is out of copyright and freely available. See for example, this ebook (the one-to-one map appears in Chapter XI). Unfortunately…

Figure 3.4 Three twenty levels of web map hierarchy

The code below retrieves an OSM tile from level 0 all the way down to level 19 for the latitude-longitude coordinates of the Broolyn Wind Turbine in Wellington.

Figure 3.7 Two simple world projections

Use the supplied World dataset (in lat-lon EPSG 4326) and make projections as required.

Figure 3.8 A loxodrome on the sphere and projected

The figure produced below extends to ±89° which makes the point even more clearly, but doesn’t give a nice square Mercator projected map. See also Jason Davies’ page about…

Figure 3.9 Equal area world in a square

This equal-area projection could replace Web Mercator as the top level global web tile ‘world in a square’.

Figure 3.10 Raster aggregation and disaggregation

This figure shows how you can’t recover raster information after aggregation.

Questions for discussion

Is scale all in our heads?

© 2023 David O’Sullivan