Map of Betio I., Tarawa Atoll
Posted 09 October 2005 - 02:09 PM
Here I took a later chart (found on the marvellous Historic Maps and Charts page of the U.S. Coast Survey), imported it to Photoshop, cleaned it up, modified it to match the 1943 configuration of the island, and added new legends. Becuse I flattened the colors a lot to make it look fresher, it makes a very compact GIF or PNG file.
I like this pretty well. I was once a ship's navigator and like the classical nautical chart look. I've done similar charts of Wake I. as it was in Dec 1941 and Midway Is. in Jun 1942.
[I've removed the map to make room for more -- 21 Oct 2005 -- Will O'Neil]
Posted 10 October 2005 - 07:12 AM
Edit: I just saw your post in the introductions area: Welcome! That post explains your ideas behind the map a little more. Is the blue the lagoon? I think the colors are a bit non standard, and for explaining a battle (I have to admit I know very little about the pacific war) are dephts relevant? (might be better, if possible, to communicate that by shaded relief/bathymetry)
Posted 10 October 2005 - 10:02 AM
Is the blue the lagoon? I think the colors are a bit non standard, and for explaining a battle (I have to admit I know very little about the pacific war) are dephts relevant? (might be better, if possible, to communicate that by shaded relief/bathymetry)
Technically, I believe, the whole area within the circle of the atoll's perimeter (lying to the north and east of Betio in this case) is lagoon. The darker blue is the reef, but one often talks about the area within the reef as lagoon. The colors of nautical charts are not highly standardized -- these were chosen to look reasonable when printed out, but I have color adjustment layers in the original Photoshop file to permit easy modification for other purposes.
Depths are always extremely important in planning or explaining any amphibious landing, as shallow depths are the chief problem in getting the landing craft where you need them. Nautical chartmakers avoid devices such as shaded relief because they can too easily mislead navigators into a false sense of confidence. They could be used in publication maps for a general audience, but generally have not been in these contexts.
In the specific case of the landing on Betio lack of good depth information combined with lack of good knowledge of the tides to create a tragedy that cost the lives of many American Marines and nearly led to the failure of the landing. It had been thought that the landing craft could cross the reef, but in fact it proved that they could not. This forced many Marines to wade ashore through the reef area under fire, and many were killed doing so.
Posted 10 October 2005 - 06:36 PM
I think that spot depths alone are very poor at communicating patterns and the continuous surface that the earth is. As a map reader I do not like to spend a long time looking for the patterns. Spot depths alone mean that I need to scan the map and remember the values rather than visualize them ...which is how a map works. A string of numbers on a map is just a poor choice of cartographic techniques. I would strongly recommend looking into contour bathymetry if you do not like the idea of shading.
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