OHM

Open History Mapper is a project, in its early stages, whose main goal is to be an open alternative to WALS.

The need / uses

The primary use of OHM is to map linguistic features in modern languages (like WALS), but it can be used for so much more. Various ways it could be used include the following:

• Mapping linguistic features, like WALS. This doesn't have to be limited to typological features like WALS, but can be used for etymology (e.g., to visualise the geographic extent to which reflexes of a various word or form are used).
• Mapping historical sociology stuff. For example, one could look at the prevalence of various causes of death per region in 1800s Russia, given that the data were available.

Features

The software should allow users to easily

• define arbitrary areas or points,
• specify a name for the areas or points from predefined [perhaps user-generated] data (e.g., a list of languages, etc.),
• map features to areas or points (even those defined by others),
• subgroup areas and points,
• display maps of the areas and points corresponding to various values of a feature, distinguished e.g. by colour,
  • ideally include customisable and complex symbology—e.g., provide ability to display multiple features at a time, using different distinguishing properties (colour, texture?, etc.),
  • include a customisable (in terms of look, content, and placement) legend, which may include the option to switch quickly between displaying different features,
  • include d3-like mouse-hover information on areas and points,
• [down the road] upload a scanned map and geo-reference it,
• export maps for use in publications.

Software

Mapping core

The mapping core that will be used hasn't been decided on yet. Some possibilities include the following:

• OpenLayers — very powerful, but a little tricky to use?
• Leaflet — fairly powerful, easy to use
• Polymaps — seems to do a lot of cool stuff, easy to use, powerful enough?

Given the desired features, the core mapping software should support the following:

• the ability to draw points and polygons, as well as select, edit (e.g., trim stuff away, adjust points, delete points, insert points, etc.), and move them,
• ideally, the ability to display the same data in different projections (maybe a simple political background map would do this okay, but terrain wouldn't?),
• plot a bunch of stuff and have a nice legend for it (see above),
• an overview map would be nice,

Base maps

There will need to be base maps in various projections. Some requirements follow:

• Projections that preserve size are ideal due to the nature of what these maps will be used for.
• Background layers should include physical maps of the earth as well as modern political boundaries and names. Use of one or the other or both should be easily user-switchable.

Physical map options

• Perhaps the technology behind Stamen's terrain maps, but with a wider set of data?
• MapBox terrain cover, MapBox terrain – very nice, but have to pay for API
• OSM Terrain layer / TopOSM – only covers US :(
• MapQuest OSM terrain tiles