Abstract: A renderer allows for a flexible and temporally coherent ordering of strokes in the context of stroke-based animation. The relative order of the strokes is specified by the artist or inferred from geometric properties of the scene, such as occlusion, for each frame of a sequence, as a set of stroke pair-wise constraints. Using the received constraints, the strokes are partially ordered for each of the frames. Based on these partial orderings, for each frame, a permutation of the strokes is selected amongst the ones consistent with the frame's partial order, so as to globally improve the perceived temporal coherence of the animation. The sequence of frames can then, for instance, be rendered by ordering the strokes according to the selected set of permutations for the sequence of frames.

Abstract: A renderer allows for a flexible and temporally coherent ordering of strokes in the context of stroke-based animation. The relative order of the strokes is specified by the artist or inferred from geometric properties of the scene, such as occlusion, for each frame of a sequence, as a set of stroke pair-wise constraints. Using the received constraints, the strokes are partially ordered for each of the frames. Based on these partial orderings, for each frame, a permutation of the strokes is selected amongst the ones consistent with the frame's partial order, so as to globally improve the perceived temporal coherence of the animation. The sequence of frames can then, for instance, be rendered by ordering the strokes according to the selected set of permutations for the sequence of frames.

Abstract: A renderer for performing stroke-based rendering determines whether two given overlapping strokes depict an occlusion in a three-dimensional scene. The renderer may then use this information to determine whether to apply an occlusion constraint between the strokes when rendering an image or a frame from an animation. In one implementation, the renderer determines whether the two strokes together depict a single view patch of surface in the scene (i.e., a single portion of three-dimensional surface in the scene as seen from the rendering viewpoint). The renderer builds an image-space patch of surface defined from the union of the two overlapping strokes and then determines whether there exists a single three-dimensional view patch of surface that projects onto the image-space patch and that contains both strokes' three-dimensional anchor points. Which stroke occludes the other can be determined by the relative three-dimensional depth of the strokes' anchor points from the rendering viewpoint.