Tuesday, 28 October 2014

A map of Cornwall in Cornish

The Cornish Language Partnership has a list of placenames in Cornwall in the Cornish language.

I have downloaded a shapefile with locations of places from www.mapcruzin.com which ultimately derives from OpenStreetMap. To this I have added the Cornish placenames, and plotted on a map in QGIS.

I still need to add in other features like rivers etc., and find something to make sure that estuaries like the Fal are shown as water rather than appearing to be dry land.

The colour scheme might look familiar if you remember the old Bartholomews 1:100k maps.

An elevation aware cycling route planner?

For some time now, I've had an idea to produce an elevation aware cycling route planner. You see, Google Maps can give you a route, but it doesn't take account of hills when deciding it.

Basically the idea I have is based on attaching some kind of cost distance multiplier to segments of route.

One idea I have had is to use the RSGISLib tools to segment a layerstacked digital elevation model, consisting on the elevation, slope, aspect (degrees from N) and then intersect this with a map of the road network (it is possible to download versions of this derived ultimately from OpenStreetMap and the OS OpenData has data available as well) to make road segments that have a consistent slope.

Then the average slope in the direction of the road could be calculated, and from this a cost-distance multiplier.

This is a segmented DEM in mid-Cornwall from the SRTM and with a pixel size of 73m, with a minimum object size of 9 pixels.

I haven't yet worked out how to complete this, one important thing is that the relevant slope is that in the direction of the road rather than the absolute value, and of course it is different if traversed in the reverse direction. So perhaps it would be necessary to convert every road into two one-way roads, so that the cost-distance could be calculated separately for each direction

Wednesday, 1 October 2014

The disappearence of Cantre'r Gwaelod

Again based on Shennan & Horton 2002:

Now just a little bit beyond the present coastline in certain places, such as near Borth where the preserved forest can be seen when the sea strips back the sand (often low tides after storms are a good time to see it).