Adobe 12040118 - After Effects Standard, Руководство

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Overview of shape layers, paths, and vector graphics
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About vector graphics and raster images
About paths
About shapes and shape layers
Groups and render order for shapes and shape attributes
About vector graphics and raster images
Vector graphics are made up of lines and curves defined by mathematical objects called vectors , which describe an image according to its
geometric characteristics. Examples of vector graphics elements within After Effects include mask paths, shapes on shape layers, and text on text
layers.
Raster images (sometimes called bitmap images ) use a rectangular grid of picture elements (pixels) to represent images. Each pixel is assigned a
specific location and color value. Video footage, image sequences transferred from film, and many other types of images imported into After
Effects are raster images.
Vector graphics maintain crisp edges and lose no detail when resized, because they are resolution-independent. This resolution-independence
makes vector graphics a good choice for visual elements, such as logos, that will be used at various sizes.
Example of a vector graphic at different levels of magnification
Raster images each consist of a fixed number of pixels, and are therefore resolution-dependent. Raster images can lose detail and appear jagged
(
pixelated ) if they are scaled up.
Example of a raster image at different levels of magnification
Some images are created as vector graphics in another application but are converted to pixels ( rasterized ) when they are imported into After
Effects. If a layer is continuously rasterized, After Effects reconverts the vector graphics to pixels when the layer is resized, preserving sharp
edges. Vector graphics from SWF, PDF, EPS, and Illustrator files can be continuously rasterized.
Aharon Rabinowitz’s “What are Raster and Vector Graphics?” video tutorial—part of the Multimedia 101 series on the Creative COW website—
provides a general introduction to raster images and vector graphics.
About paths
Several features of After Effects—including masks, shapes, paint strokes, and motion paths—rely on the concept of a path . Tools and techniques
for creating and editing these various kinds of paths overlap, but each kind of path has its own unique aspects.
A path consists of segments and vertices . Segments are the lines or curves that connect vertices. Vertices define where each segment of a path
starts and ends. Some Adobe applications use the terms anchor point and path point to refer to a vertex.
You change the shape of a path by dragging its vertices, the direction handles at the end of the direction lines (or tangents ) of each vertex, or the
path segment itself.
As a path exits a vertex, the angle and length of the outgoing direction line for that vertex determine the path. As the path approaches the next
vertex, the path is less influenced by the outgoing direction line of the previous vertex and more influenced by the incoming direction line of the
next vertex.