31 May 2017

Building a Web Map, part 8

Since I'm going to be running a game today,  I wanted to be able to use the web map.  A big part of that usefulness fro me is the presences of hexagons for distance measurement. I know I already have a scale bar on the map, but I always find those pretty useless on interactive maps. So I generated hexagonal tessellation in ArcMap at 3 different scales: 6 mph, 24 mph, and 96 mph. I know Mystara is traditionally mapped at 48 or 72 mph at the smallest scale, but I felt I should be consistent in size difference because 24 is 4 times 6, whereas 72 is only 3 times 24, which works for the 8 mile hex, but I'm using 6 mph because I'm trying to stay consistent with the older source material and the 6 mile hex is great for measuring in general. Yes, that was a ridiculous run on sentence.

You may notice that the hexagon layer doesn't match up with the size of the hexes in the original maps. This is due to actually placing the maps in their geographic locations on Earth. I'm am positively sure that the "Continental Map" published in X1 and "The Grand Duchy of Karameikos" map published in the Expert set were developed prior to and independently of the "Known World" map which appeared in the masters set. So the map from Isle of Dread was smashed into a place on the world map that looked like it might fit, and the scale was retroactively applied to the world map. The scale of the hexagon layer and the scale bar are the accurate scale produced by matching the "Known World" map up with the map from the Jurassic, giving me actual geographic coordinates and a basis for an accurate map. If you prefer the original scale, it is fairly simple to convert; in most places the original hexes are 2/3 the size  they are supposed to be. So the 6 mile hexes in the original map are each about 4 miles across, thus the 6mph layer would be 8mph at the old scale.

Also you may notice a distortion of the hexagons as you get closer to the poles. This of course is due to the mercator projection used in pretty much all web maps. The hexagon tessellations appear as regular polygons in the mollweide projetcion (the original projection of the Known World map), but become warped in any other projections. Displayed in another equal area projection, such as the cylindrical equal area projection, the hexagons still maintain their area while shape is distorted.