Mapping Japanese City Spaces: Introduction to the Maps
Turns out the Japanese Ministry of Land, Infrastructure, Transport and Tourism has shape files for all the country’s DIDs for all census years, freely available on its website here. These aren’t images, but raw data that have to be opened by a specialized mapping program. To the best of my knowledge there are no pictures using this data, so I’ve created maps of Japan using the DID shapes on a Bing Maps base, which provided the best contrast, and balance between detail and simplicity.
I colored in the shapefiles to represent the population density of the DIDs, with a color gradient as such:
with a change of 100 people per square kilometer corresponding to a change of 2 RGB points. Those points are subtracted from G for yellow to red, subtracted from R for red to black, divided among all three and added for black to white, subtracted from G for white to purple, then divided among R and B and subtracted for purple to black. This seemingly haphazard gradient was chosen because a simple yellow-to-red gradient didn’t provide enough contrast between the density levels most common in urban areas, and a rainbow gradient created too much color clash between the “warm” and “cool” parts of the spectrum.
In reality, most local area DIDs are all under 5,000 /km^2, with densities approaching 10,000 /km^2 seen only in the most populous metropolitan areas. Only the densest wards of Osaka and Tokyo proper are around 20,000 /km^2. Densities around 30,000 /km^2 were seen in the densest wards of Osaka and Tokyo proper back in 1960 before de-centralization and sprawl. Any higher densities were only seen sporadically in the apartment block projects built on the outskirts of cities in the 1960s through 1980s, originally built stand-alone with no non-residential neighborhood buildings to dilute their density. They were populous enough to be counted as DIDs in their own rights but too removed from the city center to be seen as part of a continuous cityscape. Since then, most of these high-density apartment projects have either been absorbed into the cityscape, or have decreased in overall density due to non-residential buildings emerging around them.