Datasheet

So why are raster images even used if you can’t scale them well? Most common displays
and output methods such as television or computer screens, or even printers, are actually
raster displays. The display devices need raster images to display the pictures properly. The
term raster originally referred to the display area of a television or computer monitor. To
form an image, the electronics in these devices “paint” it as a grid of red, green, and blue
pixels on a glowing screen. Every image generated by a computer, therefore, must either
begin as a raster image or be rasterized as part of rendering for display.
Vector Images
Why does the interface for 3ds Max look so different from Photoshop’s interface? Where
is the original image that gets altered in 3ds Max? Autodesk 3ds Max and other 3D pro-
grams work with vectors. Vectors are created using mathematical algorithms and geo-
metric functions. A vector program defines its images using coordinates and geometric
formulas to plot points that define areas, volumes, and shapes instead of defining the color
of each and every pixel in a grid of a raster image.
Popular vector-based image applications include Adobe Illustrator and Macromedia
Flash, as well as practically all computer-aided design (CAD) programs, including Auto-
CAD and SolidWorks. These programs let you define shapes and volumes and add color
and texture to them through their toolsets.
Vector files store the scene in 3D space using coordinates and equations of points in
space; and the color values are assigned through materials. Therefore, when a vector image
is scaled, the image does not suffer from the same blocky limitations as a raster image would.
As you can see in Figure 1.4, vectors can be scaled with no loss of quality. They will never
pixelate because they always redraw at the new scale.
Motion in a raster movie, such as a QuickTime movie, is stored in a long sequence of
image files that, when played back, show animation or movement. By contrast, motion in
vector programs is stored in the changes in the coordinates of the geometry and in the
math that defines the shapes and volumes.
When a Flash cartoon plays on a web page you are visiting, for example, the informa-
tion for that cartoon is downloaded into your computer in vector form. The data contains
the position, size, and shape of all the elements of the animation. The vector information
is then converted into raster images (called rasterization) so you can view the final image
or animation. Your computer renders this information on-the-fly, in real time, into a
raster display that you can enjoy on your screen.
This is roughly how things are done with 3D programs such as 3ds Max. You begin
your work in Max’s 3D space in vectors. When you are ready to render, Max renders the
scene contents into raster images or movie files that you can display. You use the tools in
3ds Max to change the geometric information, which in turn changes the scene, and then
rerender to show the output. Changing a raster image, such as a digital photo, alters that
16 ■ chapter 1: Basic Concepts
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