Strictly Spatial #23

8 September 2016


With it officially Spring you’d hope that the days would be getting longer and warmer… But no winter strikes back! So why don’t you find a spot near the heater and settle down to read through this fortnight’s Strictly Spatial. Where on Earth do you think is less mapped than the Moon or Mars? Do you know about New Zealand’s new vertical Datum? Or how about how much land has been reclaimed over the past 30 years? If you don’t know the answer to any of these, then read on!

Strictly Spatial 23aYou’d be surprised in knowing that the planet Mars and the Earth’s moon have more accurate topographic maps that America’s 49th State, Alaska. This changed last week when The White House, the National Science Foundation and the National Geospatial Intelligence Agency released a high resolution Digital Elevation Model (DEM). The DEM has been created using 2m resolution imagery sourced from Digital Globe commercial satellites. The Daily Mail has published an article with an embedded map displaying the data. There is also an Esri Storymap and National Geographic article with some interesting facts, maps and comparisons.

Strictly Spatial 23b2Last fortnight we mentioned Australia’s new positioning system. Since then a relative media storm has arisen after the BBC suggested that Australia’s current coordinate system was out by a kangaroo – amusing, yet technically correct. Spatial Source has written a brief article on the matter which you can read here.

Strictly Spatial 23cOn the topic of coordinate systems and datum’s, Lincoln University has published a very interesting blog post on New Zealand’s new gravity based vertical datum, NZVD2016. Currently New Zealand has 13 different standard mean sea levels. This can be incredibly problematic! Fortunately, as an end-user you will notice little changes, but behind the scenes there are huge changes. I encourage you all to read and understand the blog post as it is very informative and relevant to GIS.

Strictly Spatial 23dThe land and the sea are fighting a constant battle. The sea is trying to erode the coastline whilst the land is responding by collapsing into the sea. Humans are on the lands side. Over the past 30 years the Earth has ‘gained’ 172,000km2 of land with much of it from land reclamation. This figure has been calculated from a study by Donchyts The results from their study have also been published to a webmap. At the loading zoom level, the data looks very coarse, but as you zoom in the resolution improves considerably. So much so that you can see changes that occurred with the Canterbury earthquake(s)! Check out the map here!

350 years ago the Great Fire of London began in a bakery on Pudding Lane. In just three days the fire had spread to over 13,000 houses, nearly 90 churches and damaged St Pails Cathedral. To commemorate the fire, the BBC has compiled a map of events based on Samuel Pepy’s diary. You can view the map and read his diary entries here.

That’s all for this fortnight’s Strictly Spatial. Remember to stay in contact through Facebook, @InterpretGS, LinkedIn or email!