Today,
I will explain to you guys what is Z
Depth. Because many of you will undoubtedly
not be familiar with z-maps, their creation,
or their use.
The
term z-map might be a little misleading
to those who are not familiar to working
in 3D space. In high school geometry
class the concept of two-dimensional
space: the x-axis represents horizontal
space and the y-axis represents vertical
space. Whenever you work in packages
such as Painter, Photoshop, Commotion,
Combustion or After Effects you are
working solely in 2-dimensional space.
When you work in 3D you have, in addition
to the x- and y-axes, a z-axis, representing
depth.
A
z-map is a grayscale image, similar
to an alpha channel that is a graphical
representation of depth. An alpha channel
uses 256 levels of gray to determine
masking, transparency, etc. - in a z-map
every pixel in a scene is assigned a
0-255 grayscale value based upon its
distance from the camera. Traditionally
the objects closest to the camera are
white and the objects furthest from
the camera are black.
The
following figure shows you the main
scene with z-map.
The
most common use is to use it as a control
layer for a blur operation, 3D matte
extract, Fog 3D, depth of field (simulating
what a real camera would see), depth
matte, Id matte and various others.
Depth
of Field in Action:
Depth
Matte in Action
Fog 3D in Action
I
achieve these effects in Aftereffects.
In
the end, there are two main ways to
create a z-map with a 3D application
or by faking it in 2D. If the depth
effect you are going to apply is intended
for a rendered 3D element you're better
off making one in the 3D application
itself, it's the most accurate way.
For a 2D scene you can either fake one
with gradients or replicate the scene
precisely in a 3D application and create
it there - it goes without saying that
the gradient method is the easier of
the two. But both ways in 2d are very
time-taking and if the camera is moving
then think of a God.
I
hope you guys like and learn from this
tutorial and if really learn something
and any question, comments then please
email.
