Wednesday, 18 December 2013

A Study in Scale: Meryath

My article on scale was perhaps lacking in clear examples, so I have prepared some more images to show visually what I described in that article.

To recap, I have been developing the +World of Calidar on three different scales:

• World Map, 2 km/pixel
• Continental, 0.5 km/pixel
• Local, 0.125 km/pixel

The step down between each scale is a quadrupling of the previous one.  So a single 100 x 100 pixel area of the world map would become a 400 x 400 pixel continental map, or a 1,600 x 1,600 pixel local map.  It's important to understand that these scales all show the same area.

Kingdom of Meryath, Calidar, Eroded Height Map Scale Comparison, Albers Equal Area, Stereographic Projections
Kingdom of Meryath Scale Comparison
Here's what this looks like for Meryath.  Note that the full resolution local map is far too big to display at full size here, so I have scaled all the maps down to fit.  They are still in scale with each other, regardless of what size they are viewed at.

The point to take away from this is perhaps rather obvious, but its implications are not.  Clearly, higher resolutions show more detail.  Moreover, erosion produces more realistic results at higher resolutions/larger scales.  What's perhaps not so clear, but crucially important for cartography, is that the smaller scales are not meant to show things in great detail.

What this means is that even though the local scale map is much more detailed, it doesn't mean that it's better than the other maps.  Although it could be used to make the other two maps more detailed, you have to ask yourself if that's necessary – or even desirable.  Will it actually show more detail when reduced down so drastically?  There's a real possibility that it will in fact do the opposite, obscuring the important details with a mess of barely visible tiny details.

This is the crux, which I forgot to state clearly in my article on scale: world maps need only show world level detail.  Continental maps need only show continental detail.  Local maps are where you can go all-out on fine detail, but even then, if you feel like you're crowding things in, perhaps it's time to move down to another, larger scale still.

Finally, here are the three images in the scale comparison all scaled to the same size.  The local map has been shrunk down to less than a quarter its full size; the continental map is just a little smaller than full size; and the world map has been almost quadrupled from its native (rather tiny) size.  Bearing in mind the purpose of each scale, it's interesting to compare the difference in detail shown on each map.

Kingdom of Meryath, Calidar, Eroded Height Map Local Scale, Albers Equal Area Projection Kingdom of Meryath, Calidar, Eroded Height Map Continental Scale, Stereographic Projection Kingdom of Meryath, Calidar, Eroded Height Map World Map Scale, Stereographic Projection
Local Scale Continental Scale World Map Scale
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