Some places just deserve to be exported in a nice high-quality export so you can properly examine all the details of the map.

The City of Sanctuary from the community atlas is certainly one of these places. This lovely city by master mapper Christina Trani and resident artist Sue Daniel is a visual masterwork of a city map. So, I decided to try to make a proper high resolution export of this map. The result is a map 200,000 by 200,000 pixels, or 40 gigapixels in size. The .png file for this map is over 12GB in size, and even though I have a powerful computer, actually opening this source image in an image editor is almost impossible without it crashing.

Of course, providing such an image for download is useless, since nobody can actually use it, but a far better approach is to provide it as a zoomable image on the atlas website. The image viewer used for such a zoomable image loads different images depending on your zoom level, ensure that you only load what you need at any one time, making it reasonably easy to explore this gigantic export with reasonable loading times as you zoom or scroll. You can explore this zoomable image yourself by going to the City of Sanctuary map page, and then click the Zoomable Image button located over the map image. It should load reasonably quickly, but your physical distance from my server would affect loading times. I recommend you click the fullscreen button in the toolbar at the bottom of the zoomable image viewer for a much more impressive experience.

So, how did I accomplish this feat? Well, let me start by underlining that this was not a simple one-click task, it did require quite some work and a lot of computer time. Continue reading »