Skrifennow

My blog, imported from Blogger and converted using Jekyll.

Segmenting Topography with LandSerf and RSGISLib

Aug 3, 2014

As a training for segmenting Martian topography, I have done a little work on Earth.

Using the software LandSerf  by Prof. Jo Wood (the website www.landserf.org appears to be down at the moment), I created a number of derived topograhic layers from Shuttle Radar Topography mission data, i.e. slope, aspect, and plan, longitudinal,  cross-sectional, profile and mean curvature. I then layerstacked these files (taking the aspect in degrees from north-facing).


Using RSGISlib to segment these (using min 128px sized objects where a pixel is ~ 72m) I get results like this:

The curvature layers seem to enable it to segment along ridge and valley lines and it can sometimes be seen how the topography is orientated spatially.










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:

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