Camera Tracker for NUKE X - Part 3: Solving Stereo Video Lecture | Create Visual Effects with Nuke - Professional Skills

welcome to this short series of
tutorials on the camera tracker node for
new cakes in this third tutorial we're
going to look at tracking and solving on
stereo footage so I've got a clip here
with a very smooth small camera movement
and we've got a left and right side
we're going to track and solve so
there's left view and here we've got
arrived view okay so if you look at the
camera tracker in a stereo setup there's
a few differences you're going to notice
so first of all you get a principle view
you can also create a stereo rig and
under the solver tab you have a set of
solver constraints for stereo footage so
the principle view sets up which view is
used as the hero for tracking and
solving so typical style we're going to
want to set up our tracking first so
let's preview the features so the way
the tracking works is it picks up the
features in our principle view and
tracks them across to the right eye here
because we're using left as the
principle and overtime so the tracks it
creates exist in all views so I'm going
to be lazy with this shot I'm not going
to create a garbage map there's only a
few track points is picking up on the
people but actually I'm going to stick
up the number of features to track
because I'm going to have to so throw
away some of the ones that have been
picked up on the moving foreground
everything else looks pretty reasonable
so we've got lots of nice points on
fixed locations to track and solve from
and switch that off okay so let's track
so here we have to track results and we
want to review how good those tracks are
over the time line so it's picking up
quite a few points here on the people
we're going to want to make sure the
solver throws those away so let's go to
the refine tab and have a look at our
tracks first
so there are a few tracks here with a
short length so I'm just going to bring
up this minimum length threshold make
sure we're only using a nice long tracks
which are in view for a long periods of
time and you can see that there's quite
a few red points coming out in the
moving elements so this is because the
tracker
there's a camera solve as it does the
track so it's terminating these tracks
because they're moving too much
they don't fit a fixed 3d points so
straight away we can go and throw away
quite a lot of the points on the people
that's to leave those rejected points
okay we should have good tracks now
let's go and solve the camera
this let's go and have a look at our
ride fines app and have a look at the
errors we've got on our tracks so it's
not too bad there's some obviously with
some glitches so let's bring down that
Maximus threshold something reasonable
let's go for some nice round numbers
here and make sure we have some green
tracks covering the sequence you notice
it's rejecting all the ones that are
near the people where the tracking has
gone wrong and let's go in and clear
those out I'm fairly confident because I
don't have to recalculate itself because
I can see there's lots of green tracks
locks around here
okay so I'm fairly happy with the tracks
let's just go and solve it from those
tracks
okay it creates a stereo rig and let's
have a look at those cameras in 3d
so what's particularly important with
asserting CG elements here is to make
sure that we don't have any jitter
between the left and right eye because
once you put down that CG element and
the camera and shifts you'll see ruin
the stereo effect so I'm going to look
at the translations I've got out you can
see here there's a little bit of noise
coming in so one thing you can do in the
camera tracker under the solver tabs is
you can set the smoothness so what this
will do is it will smooth out the camera
path but it will recalculate the
rotation to lock the camera down to the
plate so you get a nice smooth motion
but the rotation will still satisfy the
motion
so feed the crowd translations again you
can see you've got a nice smooth path
but I should see this was one on a track
and I actually go in and look it down to
a linear path don't need me smoothness
is going to be completely straight let
us solve again with a linear camera
constraint
you can't we look at our translations
there's no just between those two left
right eyes okay so let's go in and set
up our scene let's set some ground
points check in 3d be on the grounds yep
so let's set the ground plane to those
selected points
and have a look at that camera past
again so perfectly straight so I
mentioned before you get a set of extra
silver constraints now under the silver
tab so aligned stereo cameras here means
that it's aligning the optical access so
you can see here the left and right side
perfectly sit on top of each other now
the reason for this is because there's
an ambiguity between the position so
position of the camera and the depth of
the points and the focal length it
calculates so if you want to make sure
those cameras optical axes is a lockdown
you use the align stereo cameras
constraints we can also constrain the
inter actuals so this is a locked off
stereo rig so I'm going to set the
international distance and convergence
to be constant and it will go away and
it will calculate the best distance and
best convergence okay so we've got a
locked off camera on a perfectly linear
path let's check our errors is still
good 1.17 that's reasonable now in
stereo you also get to set the inter
actual distance for the camera to scale
the world up so when you do a camera
self by default everything sits sort of
in the unit world so you'll see this is
a distance of one everything is around
worn away so that's not realistic so I
can go in and I can set an interactional
separation here and it will go and scale
up the world appropriately so there's
our scaled world
okay so that's the end of the third
tutorial in the series for the camera
tracker in UK X which just looked at
stereo camera solves stereo adds a few
more parameters into the camera tracker
you can set the principle view that is
used to pick up and track points the
tracks exist in all eyes and the solve
solves all cameras simultaneously so it
gets the best fit left and right for you
for the tracks that exist in both views
simultaneously the solver adds a few
more constraints so you can set the
optical axis is aligned you can also set
it as a locked-off inter actual and
locked off convergence under the scene
tab you can also set a locked-off
interaxial distance so you can set the
appropriate scale in the world