My blog, imported from Blogger and converted using Jekyll.

The population of Wales represented as a multicomponent 0-manifold.

Jul 14, 2014

Martian glaciers in Crater "Greg"

Jul 13, 2014

As mentioned by Hartmann et al., there are a number of glacier-like features in the Martian Crater "Greg".

I am studying Martian glaciers, based on the list published in Souness et al. 2012 for my MSc dissertation.

Here are a couple of graphics, showing the Souness glaciers in the Greg crater:

I have used Google Fusion tables to plot these and exported to a KML for use in Google Earth using the CTX camera mosaic as a backdrop. The centres are plotted as snowflakes, heads in blue and termini in yellow, with purple and green used for the channel sides at the midpoint.

Below, I have tried using RSGISlib on Mars, using a layerstack combining topography and imagery from Mars Express HRSC, using a colour palette to show a segmentation. I'm not yet convinced the segmentation is picking them out, but work continues...

Cornish identity in the 2011 census - part 2

Jul 10, 2014

Here is a map showing people throughout Cornwall, England and Wales, who listed Cornish as their national identity:

These are random dots below 300m.

Here is a map of people expressing Welsh identity:
And English (reduced in number by a factor of 10):

Cornish identity in the 2011 census

Jul 9, 2014

Here is a dot map representing all people in Cornwall declaring Cornish national identity in the 2011 census, generated using random points clipping the census output areas to the OS OpenData buildings layer.

As a heatmap, classifying by powers of 2:

Speakers of the Welsh language according to 2011 census.

Jul 8, 2014

Much was written about a relatively small drop in the percentage of Welsh speakers in Wales as recorded by the 2011 census. I'm sure an astronomer wouldn't believe it was anything other than statistical noise if her data showed a 1% change from one survey to another....

Nevertheless, it is possible to visualise the data in a different way to the standard colorised maps you often see about these things.

One way is the restriction of the census output polygons to where buildings exist as the Datashine project did. However their website does not display statistics for Welsh language skills, since the detailed question was not asked to census respondents living outside Wales.

How about we use a QGIS plugin to give each Welsh speaker in Wales (or actually here, anyone claiming any skill in Welsh) a circular piece of land 50 metres wide, randomly located somewhere below 300 metres above sea level in his output census area polygon:

So here we have the opposite problem to the issues with the typical visualisations with colourised choropleth maps where large but sparsely populated areas dominate visually,namely that denser areas are oversaturated at this scale.

It is also possible to take this random dot distribution and make it into a heatmap (click on the image for a larger version):

I also downloaded the OS OpenData buildings layer for the relevent grid squares covering Wales, and produced another dots distribution (this took QGIS some time).

This produces the following dot maps, giving each Welsh speaker 50 metre and 20 metre diameter circles of land respectively:



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