Contour interval in TOC

[Volcano Man]

Map scale is usually decided based on several factors...

1) The range of elevation the map will cover. In most cases, if the elevation range is 0m to 1300m, and there aren't but so many elevations "steps" (13 to be exact), then its obvious what the interval must be (about 100m per step). Some maps have varied elevation though, they might be 100m per step, then 250m above a certain elevation in these cases where elevation range is even higher. For example, I was working on a map recently where the elevation range was 0 to 1600m. I decided the contour interval would be 100m until 600m, then in intervals of 250m after that. Of course it is not optimal but you have to work with what you have, and the rationale was that once you get into the 750m elevation, you are beginning to talk about mountains, so the difference between 750m and 1000m is usually an elevation change that happens within the 1km hex anyway.

2) The source map. Usually you cannot find a source topographic map that has better than 50m resolution, and such is the case for most eastern front maps if I am not mistaken. You very well cannot make a 20m contour map if the source map is in 50 or sometimes 100m intervals. ;) And no, don't even suggest using Google Earth unless the map is going to take a year or more to make (forget it).

3) Map designer's sanity. If you have never actually made a map yourself, you cannot really understand how difficult it is to read the elevations. If you go too low on the counter steps, then the map actually loses some detail because within a 1km scale you often cannot represent 20m shifts in elevation accurately, even if the source map had that sort of contour line resolution. 50m allows the map designer to realistically make the map within something like 6 months, and not go insane doing it.

Personally I don't know who made the 20m per contour elevation maps, but there is a reason why there aren't that many of them. Maybe the source maps were fantastic, or likely they are of areas that are pretty much flat as a pancake. Usually the flatter an area is, the better the source map resolution (they might be in 10m intervals, if there are very few elevation shifts). I would would say that 50m contour interval is the established norm though, at least it is the most often used interval, especially in the largest maps.

In regards to F14, anything less than 50m interval is not practical because the elevation range of the terrain would exceed the allowed number of steps available. And in regards to EP14, the desire there was to keep it similar to F14, and to allow for greater mobility (and again, map maker sanity, source map limitation, and so on). I personally like the 50m standard myself.

Anyway, hopefully that sheds some light on the issue. ;)

edited: typos