Paint Effects goes beyond traditional paint in that the strokes are three dimensional and editable. Each stroke is an object in your scene. You can paint strokes on the grid plane of the perspective view or directly on other objects, then you can transform them, change their shapes, and change their attributes.
You can use the same traditional Paint Effects brush presets in 3D that you would use on a canvas (for example, airbrushes, felt-tipped markers, oils, pastels, pencils, pens, and watercolors). Just like painting on a canvas, these brushes leave paint along the stroke path. But better than painting on a canvas, the paint can be three-dimensional, like oil paint squeezed out of a tube. While a bumpmap texture applied to a surface only gives the illusion of three dimensions, the paint applied to Paint Effects strokes actually occupies 3D space.
But painting traditional brush strokes in 3D only touches on the capabilities of Paint Effects. Painting Strokes with tubes opens up a whole new world of possibilities. As you paint a stroke, tubes sprout from the stroke path, like plants growing from seeds. You can define how the tubes sprout to achieve very complex results with a single brush stroke.
While the stroke itself lies on a plane or on a surface, tubes can sprout from the stroke path into 3D space. You can tumble and view the tubes from another angle because they are not simply textures on a 2D plane.
In the following example, the trees were painted with a single stroke with tubes, yet each tree is distinctly defined in 3D space. The ribbon is a surface woven between the trees. The 3D nature of Paint Effects strokes makes this possible.
In 3D you can change how the paint is applied along the stroke path without having to repaint the stroke. For example, you can quickly change the look of an object without repainting it by changing the watercolor brushes attached to the strokes to oil paint brushes.
You can also apply dynamic forces to the effects you paint in your scenes and animate the display and movement of the effects. For example, you can make plants grow, make long hair blow in the wind, or make a river flow.