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Camera Tracked 3D Animations
Tracking the video
Firstly we stabilize the video. This process, while taxing on
a workstation, doesn't actually require much human time - just
hours of CPU time. All the the bumps and jumps from the footage
are removed and the result is silky smooth video. If the shot
is god then less stabilization is needed, but if it was taken
from a small helicopter or in turbulent weather then more is
needed and there is a slight reduction in finished quality.
The actual tracking of the video is partly automated task although
still requires a great deal of human time. The simple fact is
that it is a very complex process that cannot be done by man
or computer alone†. Points in the video are marked and
through a process of manual input and automated tracking the
computer determines a set of moving 3D coordinates that depict
where the camera was at each point in time. As you may imagine,
especially if you have a mathematical background, the computational
power to determine this and track the points is somewhat huge
and would have been next to impossible in the recent past.
The process of tracking a few minutes of video footage can take
days, possible weeks, depending on the quality of the shoot and
the subject.
Adding the 3D animation
Building the 3D model itself is a different process again, so
from this point on we will assume it is done. The camera coordinates
are brought into the 3D scene as is the stabilized footage. Then
there is another painstaking process, which is aligning the
camera and the 3D model with the video background. Even though
the footage is tracked the coordinates will not actually relate
to the 3D scene until adjustments are made. This may take hours
or days to get right.
Then the lighting in the 3D scene needs to be adjusted to match
the lighting on the actual day the video was shot. The idea is
to get a seamless combination of the model and reality.
Other factors come in to play as well, such as foreground objects
in the video. These require a technique called rotoscoping, which
is a moving layer of transparency that is added to the final
3D rendered footage to ensure that anything that is supposed
to be in front of the building is still there after the 3D footage
has been added. Once again this is a computer/human combination
that can take some time. Normal rates for Archiform 3D to create
camera tracked 3D animations do NOT include rotoscoping and we
will shoot to avoid it's need, but if you require it we can do
it for an additional fee.
Part 2 of 3
Next Uses for tracked 3D
animations, Sample movies >
< Back Introduction, Shooting the video footage
†Humans could do it but the process would
take way too long
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