Creative Commons License
Where the stuff on this blog is something i created it is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License so there are no requirements to attribute - but if you want to mention me as the source that would be nice :¬)

Friday, 15 December 2017

30 sec animated clip - if we pulled out a 10m plug that was at the bottom of the #marinas trench what would happen

Text from you tube "A simulation of draining the world's oceans by pulling a hypothetical "plug" in the Marianas Trench, inspired by the work of Randall Munroe of XKCD: "

Text from this reddit string of posts "A few years ago I bought the book What If? by Randall Munroe of XKCD fame, which included a map showing what would be left of the world's oceans if you pulled a 10m plug in the Marianas Trench. He did a post about it online here as well. I decided to build a model (likely similar to what he built, given the similarity of the final result) that would allow me to animate it.

I used the ETOPO1 Global Relief Model, which has a pixel size of about 1.8km across. It's the equivalent of a 233MP photograph in size and includes of the earth's elevation and bathymetry (i.e. ocean elevation). I also used the Natural Earth Oceans and Lakes + Reservoirs data sets from here. Much of this data was combined or converted between vector and raster using various GDAL tools, whose scripts you can see here

Most of the processing was done using GeoTrellis in Scala. Full source is here. The key was a scanline flood fill algorithm (a fancy term for the paint bucket tool you might have used in MS Paint) that was adapted from Lode Vandevenne's work, which was modified to support wrapping at the edges so that it could be used on a globe. It's here in the source.

The math for calculating the time is based on a simplified version of the Bernoulli incompressible flow equation. Basically, the volume of the water that drained divided by the flow rate calculated from this equation. It can be seen here. It slows down near the end because each frame represents a 10m drop in the ocean, which takes less time as the volume of accessible water decreases.
If you're interested in a less brief and easier to understand explanation of all this, let me know and I'll put a blog post together covering the technical side in a more digestible way.

Also, for those asking:
  • Here's a video version to make it easier to view for some
  • It's going to Mars
  • Other oceans aren't necessarily deeper than the Pacific, they just get landlocked and stop draining
  • Many lakes will likely stick around since they are fed from rivers and direct rainfall
  • The continents drift, but not that much, over this time span
  • The plug is 10m in diameter (that's metres, for the Americans)
  • No, there's not actually a plug

Thursday, 14 December 2017

6min 51sec @TheRSA clip - Why We Need #Global Solidarity More Than Ever with Elif Shafak

Text from you tube "Award-winning novelist, public intellectual and political commentator Elif Shafak offers cautionary advice about the provisional nature of democracy in the west and the rise of populism – and how close we are to slipping back at any point."

Wednesday, 13 December 2017

3min 20sec #haylevels clip - Thomas Telford - his story by Julian Glover


Text from you tube "Thomas Telford began as a shepherd boy and became one of the most influential engineers of British history. Julian Glover timelines his life and work."

Sunday, 10 December 2017

2min 21sec @wef clip - when young people don't believe in democracy

Text from you tube "When young people don't believe in traditional governance, they don't participate, says OECD Secretary-General Ángel Gurría, which has led to some very unexpected results in the past year. He insists that the time is now to embrace multilateralism, not shy away from it."

Friday, 8 December 2017

5min 49sec @TheEconomist clip - Elon #Musk 's #hyperloop could revolutionise public transport

Text from you tube 

"Elon Musk's Hyperloop technology has the potential to revolutionise the way we travel. In a contest he held in Los Angeles, some of the world's brightest engineers gathered to find the best way to make this billionaire's pipe dream a reality."