Here is the back story to the exhibition:

 

Here is more information about the CG car crush film we made:

 

This is our initial Fiat car crushing reference.

 

We were given access to the CAD model for the Fiat 500.  We needed to convert this from surfaces to polygons for use in Maya.  The resulting polygon model resolution was important for correctness and performance of any dynamic simulations we were going to test.

We needed to decide how to crush the Fiat 3D model, so some R&D was necessary.  nCloth was one of the main options so I embarked on many tests, as shown below.

 

These are initial tests with a basic car model, and some standard nCloth presets.

The tests with nCloth presets continued with different shaped geometry, and different resolutions to see if we could replicate metal deformation, and at what resolution gave the best results.

Performance is important because a car has so many parts, so the processing power required to simulate a car being crushed is enormous.  We needed to have the geometry as low resolution as possible, so it was important to test the look of the poly models with and without smoothing,

Applying some basic shaders

Building on the tests so far, it was time to try a low resolution Fiat model to get a feel for crushing something similar to the car we were aiming to simulate crushing.  In addition, we needed to get some basic shading and redering in place to start to previs the crush.

The results so far were promising, but the geometry wasn't joined together or colliding in a realistic way.  More tests were needed.

 

Next we had to look at what resolution would be needed to give the right look, and how do we approach similating every part of the car in one simulation.

We had to start looking at how the internal structure would crush and collide againts itself with the force of all interconnecting parts acting upon one another.  A number of internal structural tests were performed.

Lastly, we needed to compare the difference between crushing models made with tri's vs quads.  This had an impact on the correctness of the simulation and also the quality of the deformed surfaces.

The next option to research was using a sophisticated dynamic simulation engine.  We did some tests with the film department's bespoke solution for dealing with realistic metallic deformations.  It is based around the bullet physics engine in Maya, and was used for all the destruction in the film 'Gravity'.

 

To create any form of realistic model destruction, first a specific dynamic simulation model needs to be built with realistic physical properties.  The model is based around building blocks linked together to form a solid structure that forces can be applied to.

From there, a poly model can be skinned to the dynamic model, and the resulting deformations can be seen below.

Next option was to look at simpler approaches that wouldn't be too processor intensive, or costly to setup.  We tested Framestore's Wrap Deformer, which uses a low poly model to envelope our high-res model, and then we deform the low-res model.

Another possibility to explore was the idea of hand animating the deformation to give us more artistic control.  One approach was to create an animation rig that the chassis model could be skinned to.  The outer panels could then be stitched to the chassis and simulated with nCloth.

Some of the final tests involved tearing.  There are a number of materials that could possibly break apart in a car, so we needed to look at ways to animate that phenomenon.

Finally, the glass smashing is a major part of the spectacle of a car being crushed.  We had to look at ways to approach this, and Houdini proved to be the best solution.

After all the R&D tests above, it was looking like an enormous challenge to simulate the realism and detail of crushing a full car.

 

After some lateral thing, one other avenue was proposed.  Contacting companies that do car crash simulations who use FEA (Finite Element Analysis).  FEA is a common approach in the auto industry to mathematically model crash scenarios for car models.  Every car model usually has an associated FEA model available.

 

We contacted Altair, who have developed 'Hyperworks' software, which is used to simulate car crashes.  They were interested in getting involved, and from there we did the next series of R&D tests to determine if it was feasible.

 

Here are renders of the first car crash test data they sent us:

 

The above tests proved we could import and use there 3D model data, however it was all one combined geometry.  Next we needed to see if we could successfully animate individual parts, and render them to a high standard.

The tests above worked and now we needed to see if the Fiat could be crushed in the way Ron Arad had visioned.  It was a very slow process to simulate the full car being crushed (approx 24 hours), so we only had a few opportunities to get it right.  The final resulting simulation is shown below.

Fortunatley the results looked great, so we were ready to see if we could import and process the full set of car crushing data.

 

A script needed to be written to import, process and link the animated crushed data for every part.  This was a lengthy process that took a number of attempts to get right and iron out any data issues.  Once all the issues were resolved, the parts were processed in stages and then put together into one master scene.

 

Here are the resulting renders of the converted and animated car crush data.

After successfully processing and animating all the car parts, it was time to start putting some realistic shaders onto the Fiat.  These are some of the initial tests.

From there, we needed to decide on the look of the lighting.  Below are a number of lighting tests.  The first image is the lighting reference from Ron Arad's team.

Here are some of the lighting options we considered.

The main crush animation did not include the glass or any smaller internal or external parts, so these needed to be simulated or hand animated separately.  Here is an example of some of the glass test images.

 

Finally, it was time to start comping all of the elements together to get the final photo-realistic look.

 

Additional hand animated parts included the front and rear wipers, car seats, steering wheel, front and rear license plate and the car arial just to name a few.

The final result after months of collaboration!