We’re still looking at the effects of Hiroshima and Nagasaki.

Science magazines has some striking visualizations of the atomic bombing’s long-lasting repercussions in their latest issue – and have had their graphics managing editor, Alberto Cuadra, explain what it took to get those illustrations there:

This seemed like a straightforward project. Hiroshima has been closely studied for decades by the Radiation Effects Research Foundation (RERF). Jointly operated by the United States and Japan, the organization monitors affected populations in both Hiroshima and Nagasaki, which was bombed a few days later.

As we began conceptual development, RERF provided us with statistical data. We obtained a map showing the location of all the Hiroshima survivors in the study, each location color-coded according to the amount of radiation they received during the blast.

But as we began to build the graphic, things quickly became less straightforward.

First, we found that RERF carefully protects survivors’ personal data. They declined to share the geotagged information that we needed to reproduce their visualizations of survivors in our own graphic.

Second, we could not find files showing the complete city layout as it was in 1945. Although many military aerial photographs showed the city before and after the explosion, none of them covered a large enough area of Hiroshima for us to plot our planned diagram of radiation effects.

Without a historic map of the city that our software could use, we had only two options that would work within our deadline. We could use a modern satellite image of the city, or we could manually trace a historic map into our system.

The first option seemed inappropriate. Modern Hiroshima’s urban area is significantly larger than in 1945. And it felt out of context to build a visualization about effects of the A-bomb over the modern city.

So we chose the second option, searching multiple historical maps. After reviewing all the candidates, we selected one created by the U.S. Army Map Service in 1946. This had everything we needed: a detailed layout of the city streets and a detailed account of the areas totally and partially destroyed by the bomb.

The only problem was that we needed to trace the map’s detailed information into our software by hand. This was a tedious yet strangely satisfying task, recalling the 1990s, when print maps were routinely scanned and traced into computers in newsrooms across the country. It also called to mind the exacting work of earlier generations of cartographers who meticulously created maps like this on paper in the era before modern geographic information systems were developed.

Check the link for some memorable graphics.