Any rendering style that does not try to
create a photographic look is termed non-photorealistic, thus it is
Non-Photorealistic-Rendering.
There are many advantages of non-photorealism depending on the purpose and “visual goal” such as:
· Facilitating the
interpretive process: not depicting every details
· “Amplification by
Simplification”: concentration on main features
· Immersion in
stories: more people can identify themselves
· Quick drafts: get
impression of big picture without inspecting fine details
The applied areas include:
· Technical
illustrations
§ Manuals, reports…
· Simulation of
traditional artistic technique / painterly styles:
§ Creation of
cartoons
The following presentation will give you basic idea of the authors’ system how to draw strokes directly on 3D model and render the scene from new viewpoint, and also briefly introduce the algorithm behind.
The introduced
system gives artists control over the look of a scene
View-dependant automatic adaptation of stroke numbers and placement
From a recent survey we can learn:
1. Much of the work
on NPR addresses the production of still images
2. Some system for
rendering 3D scenes have addressed the challenge of providing temporal coherence
for animations
The authors’ work
1. Addresses
interactive rendering
2. Maintains
temporal coherence
Basic Concepts
Media Simulation: Overall
impression of drawing, style dependent
Stroke: Colour, opacity, width,
narrowing at endpoints, halo
Base path (Cutmull-Rom spline) with offset
Visibility determined through ID reference image
Rendered as triangle strip (optionally textured)
Focus on
stroke-based rendering algorithms
Three main
categories of strokes:
Silhouette & Creases: Basis
of a drawing
Shows
shape of object
Decal: Large surface features
Hatching: Conveys light & tone from different
density of one-colour pencil strokes
Qingley will show to you details of the
implementation and Yuman will end with the limitations and results.