Eyeon Dimension Optical Flow Overview Video Lecture - Eyeon Fusion A Practical

this video is a brief overview of the
optical flow workflow within ion
dimension ion dimension works within ion
fusion and requires fusion 6.31 or later
dimension could be accessed by the bin
system menu tools inside fusion and of
course tool access scripts like control
spacebar let's have a look at an optical
flow workflow in this example we have
footage of a monkey climbing in a tree
the first thing we need to do is
generate the optical flow the optical
flow creates a series of BAC vectors and
forward vectors between the two adjacent
frames this data lets us know how the
pixels are flowing between the series of
frames once generated we can then go
into flow speed to retime the footage
the optical flow has two different
methods of generating vector results
these are computationally expensive
methods that are very accurate in
working out what's happening in the flow
of pixels between the images there is an
advanced set of controls that have been
preset to give the best results in their
default settings while this workflow is
rather simple made up of just four tools
and because the optical flow can be
expensive in terms of computational time
we suggest you write the optical results
out to an intermediate format like e^x
ARS this format can store images and the
vector data ion offers groups of render
nodes for use on a render farm or other
computers to expedite this process once
you have the intermediate format the
optical flow tools are very quick and
interactive using the flow speed we have
now slowed this footage down five times
the other tool is the flow stretcher
which uses a spline to do nonlinear
speed changes here we're gonna have it
very slow speeding up and right at the
end slow down again let's have a look at
the results
a closer look at these time-based tools
show that the interpolation method in
these tools have the choices of nearest
blend and flow the flow method uses the
vectors that we pre generated to create
the in-between frames there are four
checkboxes under the source frame and
warp directions heading what this means
is that they use the previous frame with
the forward vector and the next frame
with its forward vector to create the
in-between these two results will be
blended together we can also use the
previous frame with the back vector and
the next frame with its back vector as
well or we can use all four results that
can get blended together to receive our
final result depending on your footage
you may have to experiment with
combinations to achieve the desired
results the next item is depth ordering
you have a choice between the slowest
vectors on top or the fastest vectors on
top this is used to determine which
parts of the frame need to be on top of
the others as parts of the image will
overlap this parameter controls the
overlap rendering in our example the
monkey is moving but the vectors are
actually moving from the tilt from the
camera which is happening very slowly
the slowest vectors will be the ones
that we use on top and the monkeys
vectors will sit below two additional
tools that use the optical flow method
are the repair frame and the tween tool
the repair frame tool looks at
sequential frames and repairs frame
contaminants like dust and scratches for
example we have a single scratch on this
frame so if we navigate there we can use
the repair frame and that will fill in
the difference from the forward and back
frames and remove the scratch the repair
frame self generates the optical flow
directly and uses blend between the
previous and next frame using the
forward vectors and the previous and
next frame using the back vector
depth ordering choices our fastest or
slower on top a similar tool is the
tween tool and it can be used to
generate a frame that's completely
missing out of the sequence for example
we have frame 1 and frame 3 and we want
to create frame 2 between tool solves
this by looking at two frames and
creates the in-between frame using the
results of the optical flow data the
optical flow controls in the repair
frame and tween use the same methods of
deriving the vector data as in the
standalone optical flow tools including
the advanced controls the primary
difference is that the tween contains an
interpolation slider that allows for
nonlinear control of the warp from frame
0 the frame before and frame 1 the frame
after a practical example of its use is
if there were a sink difference on two
cameras that is not a full frame we can
solve that by using the tween tool to
generate the adjustments with a
nonlinear interpolation such as a half
or quarter frame this video covered a
simplified explanation of the dimension
optical flow toolset for a more in-depth
coverage please consult additional
master class videos and the dimension
online manual at manual DF expedia.com