Real-Life Communication
You are a computer animator and you are talking with a new client,
Sherry, about a commercial she wants to make for her Internet service. She
has decided she wants an animated sequence and has come to you for help.
In
order to figure out what to create for the client, you need to go over her
ideas. You take up your pen and paper and listen as Sherry tells you what
she wants.
"Your main job is to draw and to add color, but you have
to know what your client wants," says animator Caroline Paul. "You have to
be able to communicate with the client about the subject, and then through
animation, be able to communicate the idea."
You also need to know
what type of rendering would be most appropriate to use for the sequence.
Rendering is the process a computer uses to create an image from a data file.
"We have lots of different ways to get a result," says Paul.
You suggest
that Sherry's idea would be best done in ray tracing rendering. She doesn't
understand what you mean, so you explain rendering to her.
Read the
excerpt and answer Sherry's questions:
Rendering
Rendering
is the process a computer uses to create an image from a data file. Most 3D
graphics programs aren't capable of drawing the whole scene on the run with
all the colors, textures, lights and shading. Instead, the user handles a
mesh, which is a rough representation of an object. When the user is satisfied
with the mesh, he then renders the image.
Flat shading is the quickest
rendering method. Some programs are able to render flat shaded objects in
real time. When rendering using flat shading, the computer creates an average
color for an object and then renders each face with different amounts of black
or white added to simulate shading. Objects look flat and unrealistic. No
textures are applied in this mode.
Gourad rendering takes flat rendering
one step further. The computer figures out values of a color on vertices of
a face and then applies a gradient to the face to simulate shading. This mode
isn't much slower than flat shading.
Phong rendering takes rendering
one step further again. It actually probes every pixel in the visible area
and tries to determine a correct color for it. It takes into account all lights
and textures. This is often as good as many low-end programs. The results
are pretty good and the time that it takes to render isn't too long.
Ray
tracing gives the best rendering quality. It also takes very long but the
results are excellent. Everything is rendered including shadows, lighting,
reflections and transparencies. It also gives light a physical attribute,
which no other types of rendering do.
For example, a pencil in a glass
of water will give the same diffraction effect that nature does. That is,
the pencil will appear broken. When a computer ray traces an image, it simulates
a beam of light going out of every pixel on the screen. It reflects and deflects
the beam of light in a similar fashion to nature.
(excerpt from: Graphic
definitions created by Krys Cybulski and David Valentine)
These
are Sherry's questions:
- How is Gourad rendering different from flat shading?
- What type of rendering do good low-end computer programs usually use?
- What is the big advantage of ray tracing?