The Green, Green, QGIS of Mars (Part 2)

Here is the southern mid-latitudes of Mars, in the same colour scheme as the previous post showing the northern mid-latitudes:

The lowest elevation area of Mars, the Hellas basin has areas of bright terrain which makes the colour scheme a little confusing. Download larger version.

The Green, Green, QGIS of Mars

There are many blog posts on the Internet and even scientific papers on the evils of the spectral/rainbow colour palette for continuously varying data.

The series of 6 by Robert Simmon on NASA's Earth Observatory website is particularly worth reading and references many interesting and potentially useful sources.

Incidentally while looking for that, I saw this Image of the Day of a landslide onto a glacier in the Yukon in Canada. I wonder how often they have landslides on Mars.

Thus, I now show you the north of Mars, with the elevation encoded in a single hue palette and again overlaid with "Hard Light" on the Mars Global Surveyor image mosaic.

This will not be perfect for a quantitative visualisation, since it is not possible to distinguish between intrinsically darker areas and areas that are low in elevation.

I choose the green colour, because it leaves red and blue free to plot the classifier function values for areas similar to glacier head and extents.

The various individual HRSC tiles also have the same kind of colour palette of DTM elevation scaled locally overlaid on the nadir image HRSC. Download a larger image of this here.

If there's a North there must be a South

See also previous post for the North.

Here is the southern hemisphere of Mars. Again, I have used the same equirectangular coordinates optimised for 40° latitude.

The Souness et al. glacier like forms (such as QGIS plots them at this scale) are marked and numbered.

Lots of planets have a North

Here is the North of Mars, showing the Mars Express High Resolution Stereo Camera tiles used in my MSc dissertation, colour-coded by elevation, but also with the output of the Bayesian classifier measuring the similarity to Colin Souness's glacial form.

This is possibly a bit too colourful and the classifier output isn't really useful at this scale. The segmented DTM has red indicating similarity to glacier 'head' areas, green for 'context' areas (9x area of extent) and blue for extents.

I use QGIS to blend the elevation with an underlying nadir image also from HRSC with "Hard Light". I am not sure whether the developers of QGIS intended the Red Dwarf reference.


The coordinates are in an equirectangular projection in metres optimised for a standard latitude of 40°.

An overview of glaciers in the mid-latitudes of Mars

The paper by Colin Souness et al. in 2012 (link) gave an inventory of Martian "Glacier-like forms"

Here is where they are found plotted on a layerstack of Mars Express HRSC DTM tiles, where red=nadir image, green = elevation, and blue = slope, falling back to MOLA topography in areas I don't have that tile because it didn't underlay any Souness GLFs. For MOLA I use aspect as a substitute for the image layer.

The Souness GLFs are numbered, but not all are plotted because QGIS automatically avoids plotting too many labels on top of each other.

The coordinates are Mars Equicylindrical, with a standard parallell of 40 degrees.

Northern Hemisphere (25 to 65N)

Southern Hemisphere (25 to 65 S)