I spend a great deal of my time looking at maps - it’s a bad habbit, almost like a compulsive disorder, but I enjoy, for no reason, pinpointing known and unknown locations. When I’m in the compulsive/joyable mode I usually use the good old book version. Not e-book, just book.

Then there are other times when I use the e-book version - typically Norwegian map providers and sometimes Google/Yahoo! Maps. Those are times when I need to find information about a location and typically how to get there.

One day I was looking for an island off the coast of Kristiansand, Norway, and I found this map with a rather strange feautre.

In addition to zoom in (and out) using the mouse, it had this feature where one could choose the map ratio from a dropdown list (”Målestokk” is Norwegian and means “Ratio”). At first glance it made perfect sense, but then I started to think about it…

When dealing with a plain good old map, on a piece of paper, with a given ration - lets say 1:2000 - you can say that 1 meter on this map equals 2000 meters in real life. To me that makes sense. But when you apply the same to a digital map, it doesn’t make much sense anymore. When a digital map is projected on a screen everything is based on pixels, and pixels are somewhat difficult to convert to real life examples. What the map above says is that 1 pixel on this map, is 2000 pixels in real life. Or put in another way,  the small island in the upper right corner is 8 pixels wide, which means that it’s 16000 pixels wide in real life.

Then the question is then - if you plan to cross that island, and those 16000 pixels - how far is that?

This entry was posted on Monday, June 18th, 2007 at 11:20 pm and is filed under Misc. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.