In part one of the non-photorealistic rendering 
tutorial we looked at the ability 
of Krakatoa to produce
custom Lambert shading
and cartoon shading
using Gradients in the 
Global Channel Overrides
to control the Emission color
based on the angle of the 
Normals in view space.
A logical variation
to this approach would be to remove the
paint completely and keep only the outline.
We can switch the color
to a vector with 
a value of white,
switch the Ink to black,
and also
replace the background with white
in order to produce the same color inside and outside.
If we would render now,
we will get only the Ink
as a black outline
on white paper.
Of course we can control the thickness 
by changing the gradient
and in order to get 
a slightly less random
result
in the particle distribution we can 
uncheck the "Jittered Position"
in the PRT Volume.
This will produce slightly cleaner lines.
Another approach to control the Ink
on the outside of the shape of the 
object being rendered
would be to
use the motion blur
and produce a custom Velocity channel
which causes multiple 
versions of the same outline to be drawn
on top of each other
based on a custom velocity vector.
Let's create
a new
Krakatoa Channels Modified in the same 
Global Override
set the Output to Velocity,
the Input to a Vector value
with a value [0,0,-1].
This is the camera view vector looking
into the image.
We are going to 
transform this value
which is currently in view space
from view space.
This will produce
a vector in world space
and we are going to 
create the cross product
with the Normal
of each particle.
Then we'll normalize
the result
and multiply
by a Float
which will define the length of the
Velocity vector.
Let's enable the Motion Blur,
change the number of 
samples to eight
and check the "Jittered Motion Blur".
Now we are drawing 8 passes of Motion Blur
and we could compare
using the Presets and History rollout
to the previous rendering...
You see that there is a certain amount of
smoothness added to the final rendering
thanks to the multiple passes on top of each-other.
Now let's try to increase the Multiplier
used in the Krakatoa Channels Modifier.
Let's use a value of
thousand
and try to draw the same particles
with a much longer 
Velocity vector.
This starts producing a more "artistic" 
result where
multiple strokes are being used to define
the outline of the object.
Right now we're using "Jittered Motion Blur",
we can disable it
and try to render
the same particles
without the jittering, that means 
that eight
samples will be drawn 
without randomizing the
positions of the samples
and this will give us
an obvious set of eight strokes
along each line.
Currently the Krakatoa Channels Modifier
defines a vector
which is
perpendicular
to both be camera
view axis 
and the Normal and thus is
tangental to
the outline of the object.
We can of course
also change the
Shutter of the Motion Blur.
This will produce even
stronger
variation
and the strokes
and the final result look even more
"artistic".
Let's switch back to
something like 240
and try to generate a
less randomized look.
We could set up
a final rendering of an animation of this
object rotating at 360 degrees
in order to take a look at
the object from all directions
while being drawn using
this
"pencil" approach...
Here is the resulting animation
of 360 degrees 
rotation of the bunny.
We're going to load the sequence 
from 0 to 99
because frame 0 and frame 100
have exactly the same
orientation and we want
to make animation loopable.
Now let's
load all the frames and take a look
and the
"pencil animation"...
