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Animosaics. Kaleigh Smith, Yunjun Liu, and Allison Klein McGill University. Eurographics Symposium on Computer Animation 2005. Abstract. Animated mosaics are a traditional form of stop-motion animation . It is time-consuming and labourious. Outline. Introduction Related Work - PowerPoint PPT Presentation
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AnimosaicsKaleigh Smith, Yunjun Liu, and Allison Klein
McGill University
Eurographics Symposium on Computer Animation 2005
Abstract Animated mosaics are a traditional form of
stop-motion animation. It is time-consuming and labourious.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Introduction Arrange and rearrange small objects or tiles from fram
e to frame. Manually placing and moving pieces is time-consumin
g. Making small changes means exactly reconstructing. Packing objects to fill a desired shape is a problem in
computer science. Create static mosaics comprised of different tile shape
s using area-based centrodial Voronoi diagram.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Related Work Simulating decorative mosaics.
[Hausner A. ‘01] Take as input a rectangular image. Generate a mosaic composed of rectangular or oval
tiles Discuss methods for tile orientation
Jigsaw Image Mosaics. [Kim & Pellacini ‘02] Define a metric that measures the quality of a tile pa
cking. Both the tiles and containers can be arbitrary shape
d.
Related Work
(a) packs a single tile shape well. (b) achieves tight packings with irregular shapes. The CAVD approach (c) handles any variety of
arbitrary shapes.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Temporal Coherence andGroup Motion Minimize temporal discontinuities while
having primitives appear attached to underlying scene object.
Even if individual primitives have temporal smoothness, uncoordinated changes among groups of NPR primitives will still yield distracting.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Construction of a Mosaic Animation A temporally coherent sequence of mosaic
images over time. Given a container C (a closed polygon over
time) and a collection of tile shapes T (called a packing of C).
Three challenges: 1) Temporal coherence 2) Stylistic coherence 3) Performance
Construction of a Mosaic Animation 1) Temporal coherence:
Tiles should move smoothly, appear attached to their underlying object
Tile appearances or disappearances should be minimized
2) Stylistic coherence: Tiles are evenly distributed, tightly packed with
minimal overlaps, Tiles’ orientations reflect the edge of the
container shape
Construction of a Mosaic Animation 3) Performance:
In order to support input from the animator, the first two properties should be achieved as interactively as possible
Conflict between these three goals: Independently packing each frame will lead to high per-
frame mosaic quality, but at the cost of distracting temporal artifacts.
Very smooth, coherent tile movements may not yield pleasing individual mosaic.
Performance requirements limit the amount of time that can be spent optimizing either for packing quality or temporal coherence.
Construction of a Mosaic Animation
Take as input an animated scene represented as a collection of 2D containers (polygons).
Pick the desired tile shapes and sizes, then pack the container’s first frame.
Generate the remaining frames in two step: 1) The system automatically advects the container’s tile
from the current frame to the next 2) The animator optionally inserts new tiles and refines
the current packing to reflect container changes.
Construction of a Mosaic Animation Mosaic Packing
Tile Orientation Tile Repositioning
Temporally Coherent Tile Movement
Construction of a Mosaic Animation Mosaic Packing
Tile Orientation Similar container shapes should lead to similar
orientation fields. [KP02] preserves container edges by fitting tiles
against boundaries and previously placed tiles. Reinforce container edges but do not preserve an
internal orientation field. [Hau01] aligns tiles to a continuous orientation field
based on feature lines. [EW03] align tiles along concentric contour lines to
emphasize container shape.
Construction of a Mosaic Animation Mosaic Packing
Tile Orientation Preserve the container shape boundary by aligning
each tile with its closest container edge. To enable tighter packings and reduce image
regularity, each tile shape may have a set of equivalent orientations.
Construction of a Mosaic Animation Mosaic Packing
Tile Repositioning Use an artist-specified collection of arbitrary tile
shapes to pack a container. centroidal Voronoi diagram vs. centroidal area Voronoi diagram
Construction of a Mosaic Animation Temporally Coherent Tile Movement
Construction of a Mosaic Animation Anchor-point mapping
Cause insertion or deletions tohappen only at the boundary.
Preserve a packing’s interiororganization.
The system automatically choosesthe anchor point with thesmallest displacement betweentwo frames.
The animator can choose ifdesired.
Construction of a Mosaic Animation Nearest-edge mapping
Preserve the packing boundaryinstead of the interior.
The interior tiles move away formthe center as a container increase.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
System Details Container Specification
Containers are specified as scalable vector graphics (SVG) animation.
SVG is a human-readable format for describing 2D graphics shapes in XML and enables easy specification of vector graphic shapes and animations.
Use a graphic SVG editor (Corel WebDraw). Translate scene elements into colored container sh
apes.
System Details Packing
The artist choose the set of shapes and the number of tiles.
The system calculate the tiles size for each shape to randomly seed in the container.
Each tile is assigned its container’s color. Tiles can be add manually or automatically. The artist can also add noise to tile positions
and orientation for a more hand-crafted look.
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Outline Introduction Related Work Temporal Coherence and Group Motion Construction of a Mosaic Animation System Details Results Conclusion and Future Work
Result
Conclusion and Future Work Meets the three challenges of temporal
coherence, per-frame mosaic quality, and performance that supports interactive input from the artist.
Use area-based centroidal Voronoi diagrams to create mosaics comprised of different tile shapes.
Blend in other NPR animation styles. Pack 3D volumes with 3D objects.