Tuesday, July 12, 2016

Pyne Gould Building Collapse Simulation Video - Blender Bullet Addon Demo

What strange times we live in: I just came across a video for a Blender addon for simulating building collapses using the built in Bullet (rigidbody simulation engine) tools.  What I didn't expect though was to open the video link, and be confronted with was this:

Woah... I know this place...

This is the Pyne Gould Building, that collapsed during the Feb 22 2011 Christchurch Earthquake. It was one of the two worst hit buildings that collapsed that day, killing and trapping people. The other one was the CTV building (also in the CBD), where over 100 people died (including the mum of a classmate from primary school) when it pancaked. In other words: not really something us Cantabrians want to remember/dwell on...

My first reaction to seeing this was: Woah... this is umm... really quite close to home (literally), and for more than one reason too!

First, this is a Christchurch NZ (i.e. my hometown) event, featuring in a Blender video!?!   As you can imagine, this sort of thing doesn't really happen that much... well not yet at least!

Second, this was a building that we've parked outside on quite a few occasions... I still have memories of accompanying Dad as he went hunting for the berries of the Yew Trees located across the road from this thing...

Third, they were using the Bullet tools built into Blender for this simulation. (Sure this is a demo for their addon, which uses a few additional external libs for some extra calculations/simulation stuff, but from what I understand, the Bullet rigidbody tools play quite a role in this whole thing). The spooky thing though, is that I was responsible for laying the groundwork for bringing the Bullet rigidbody physics integration to Blender, and had been done this work less than a year before this building collapsed! Specifically, I'd been working on integrating the Bullet physics engine into Blender's viewport for GSoC 2010, and had just wrapped work on it in August that year. BUT, just a few weeks later (4th September 2010), the first of the bloody earthquakes struck Christchurch in the dead of the night - a 7.1 magnitude quake at 4:35am, kickstarting this whole series of events...

And now, 5-6 years later, we have a video, demoing some tools built on top of the Bullet rigidbody integration in Blender that I'd worked on, being used to recreate one of the grisliest and deadliest building collapses during a terrifying series of quakes in my hometown.

Woah!  Let that sink in for a moment...

** Stunned silence **

** Crickets chirping **


Umm... err... moving right along!

Back to the video itself then :)

This is a rather nice piece of work. It's quite impressive how closely they've been able to make their sim results match the actual building state. It's also quite interesting watching how the building fails during the shaking - my memory of the details of what happened there is hazy now, but IIRC, they said that this building collapsed because the outer columns failed, and that the whole building, while "up to code" (for the 1960's standard - which had long since been invalidated) was woefully inadequate (i.e. far too weak to withstand the kinds of quakes that we've since realised that buildings in NZ should be able to cope with).

The later parts of the video are also somewhat interesting (if grizzly viewing):
*  There's one shot where they show where all the people were sitting/standing in the building when the quake struck, and then we watch as these avatars fall down and/or a pinned/crushed/etc. (their colour changes when something "happens" to them...)   On one hand, it's interesting seeing the effects of the building collapse on the building occupants (it's also quite useful for the inevitable investigations that take place)... but on the other hand, I can also understand why some people may get offended/upset when they see stuff like this.

*  The other thing that really struck me while watching this was when they started doing a bit of a flythrough, with a dummy head-mounted pointlight torch, moving through the pancaked rubble. That was really quite eye opening. Even though this is all just simulated imagery (without much of the real gritty detail and detritus that would've been present), it's still some pretty freaky stuff right there... real nightmare inducing stuff, and definitely not for anyone who is claustrophobic in the slightest! For anyone who was trapped in that mess... bless them. For anyone who made it out from there alive (with or without some of their limbs): this just further underscores how amazingly lucky (in an unlucky situation) to be alive. For the first responders who risked their own lives to venture into that structure, not knowing what was inside (and without the benefit of having a complete 3d picture like this that they could have a poke around in to get a feel for what they'd be up against):  they really deserve all the thanks, kudos, and good vibes all around that we can give them for what they do, and what they did.

Anyway, it's some rather impressive work that they've done here. Hopefully some good comes out of all this work :)  It would be a great legacy of this tragic event if that were the case!

In conclusion,  it's funny how life throws some bizarre curveballs at you sometimes... :)

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