>> This video illustrates
the efforts of a team
of visualization and civil
engineering researchers towards
producing a high
fidelity visualization
of the September 11, 2001 attack
on the World Trade Center.
The visualization has to be
eloquent to the non-expert user.
The simulation was placed
into context by modeling
and importing the buildings
of the WTC plaza shown here
in color into a Google earth
model of Lower Manhattan.
A fine element analysis
simulation of the impact
between the Boeing 767
and the top 20 floors
of the North Tower was
computed using a state
of the art simulation code.
Then the simulation results
were imported into a state
of the art animation system
where the visualization
was produced.
The simulation tracked the
impact over three-quarters
of a second real time.
This sequence is 13 times
slower than real time.
All the animated geometry seen
here was created automatically
from the simulation of the data.
[ Pause ]
>> This sequence visualizes
the aircraft trajectory
between the facade and the
structural core of the building.
[ Pause ]
>> Notice the oscillation of
the ceiling during the impact.
This reverse angle shot
visualizes the important damage
sustained by some
of the core columns.
Using a camera with a distant
hitter plane [assumed spelling]
this sequence simultaneously
visualizes the two floors
that sustained most
direct impact damage.
[ Pause ]
>> Notice the right
engine titanium shaft
which traverses the
building virtually intact.
[ Pause ]
>> Plane debris re-emerges
on the opposite face
of the building.
The jet fuel in the central
and two-wing tanks was simulated
using smoother particle
hydrodynamics or SPH.
The nearby fuel particles
were lumped together
in the animation system
and the fuel was rendered
with reflections and refractions
using a retrace material.
Notice how the wing tank
fuel disperses first
as the wings are considerably
damaged by the facade.
The core columns are essential
to the structural
integrity of the building.
This sequence visualizes the
damage to the core columns
and to their connecting
horizontal beams
by rendering all other entities
with transparent materials.
Here are the core
columns exclusively.
These sequences also turn out
to provide a good visualization
of the overall deformation
of the aircraft
as it enters the building.
The simulation did not consider
the effects of the explosion
and of the instrument fire.
Here, the fuel particles were
used in the animation system
to automatically produce a
plausible fire visualization.
Apps can be seen in this
side by side visualization,
the simulation fuel particles
control the fire computed
by the animation system.
Elements that out or go
excessive stress are eliminated
from the computation by
the FEA simulation code.
These eroding elements
correspond to entities
that disintegrate such as a slab
of concrete turning into dust.
Although they do not
have much relevance
from the simulation standpoint,
eroded elements are important
for the visualization.
Eroded elements are used
in the animation system
to automatically create
and control visual effects
such as dust and
glass [inaudible].
The visualization produce
leverages of strength
of the state of the art
visualization system
which models the interactions
in detail based on physics based
over principles and of the state
of the art animation system
which produces a high
quality visualization
of the simulation results.
This was made possible by
developing a scalable translator
that automatically converts
the simulation [inaudible] data
into an animation scene.
The translator is
general and reusable
in the context of
other simulations.
