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Many picture books and graphic novels with dynamic and interesting styles

For commercial reasons, publishers create derivative digital products including animation and games

When digitising these books for animation or games backgrounds and scenes are just static images, which appear instantaneously or through fading

The entertainment industry is asking for alternatives

Commercial opportunity as Case Study:Bo children's book series Bo = transparent piglet aimed at ages 4-6 teach children how to

deal with emotions multiple traditional

painting techniques Recreate scenes from the book the way that the artist

made them unique recreation of the visual style to visualise the progression of the story/game

(as the player continues, more and more is revealed)

Tools to allow artists to quickly and intuitively create and animate hand-painted scenes

capturing the way an artist creates his picture books allowing traditional hand-painted strokes to be generated digitally Real-time animated recreation of hand-painted scenes

running on mobile devices animated recreation of captured scenes

(e.g., stroke by stroke) optimisation for mobile devices Integration in existing (game) engine Unity3D

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Physical simulation

Non-photorealistic Rendering (NPR)

Raster graphics

Raster graphics

Trade-off Accuracy

indistinguishable from reality

Performance speed of recreating captured data

Animatability ability to animate stroke by stroke drawing from start to finish

Changeability flexibility when designing (e.g., moving drawn strokes)

Artistic freedom

Immediate Mode Rendering (IMR) < PC graphics industry

forward facing polygon -> rendered -> shaded -> textured -> Z-buffer -> frame buffer

(most) android devices

Tile-Based Deferred Rendering (TBDR) < PowerVR architecture

tile based (parallel) + deferred rendering (hidden surface removal)

all Apple mobile devices

Original plan Raster graphics and TBDR Bad benchmarking test: ARM + PowerVR architecture

write-to-texture operations not efficient for pixel-based strokes

Mesh-based Strokes Combination of NPR and raster graphics

Creation: strokes are flat meshes approximating the contour of brush strokes

Colouring using textures: GPU shader program

Allows for fast rendering of meshes on the GPU

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Main characteristics Rubber paint roller for background elements Paper cut stencils for adding details Scanned paintings for animals and insects Blending for the final composition

Sampling of input points (< digital tablet) Pressure determines width Boundaries determine geometry of brush footprint Fading out of paint Use uv-coordinates as a length-parameter to determine start

and end of the stroke as a shader has no context

General fading out supported by base stroke Background consist of transparant, slowly fading strokes new parameters: fade offset + fade multiplier Unique strokes create wide texture using two dollops of paint for each stroke randomly select narrow band from texture

Pattern of white dots when rolling back and forth in a fanning pattern

due to the relief created by the paint itself as thin layers of dried paint on the surface of the roller prevent paint in between from touching the paper

Employ a black and white mask white representing spots where the paint should adhere,

black where it doesn’t add mask as texture and multiply

Create effect of individual blades of grass artist: achieved by ripping of a corner of paper, dipping it in

paint and dragging it over the canvas tool: mask with transparent inside and grass-like outside is

stretched over the length of the stroke

Using masks and additional parameters Oily brush Stencil roller brush Stamp brushes

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Management of brushes, preview canvas…

Painting, timeline, recording functionality…

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60 strokes 4500 vertices 2400 triangles

150 strokes 3600 vertices 2300 triangles

iPad2 Initially frame rate dropped from 60 fps to 5 fps

due to overdraw of transparent strokes: cover significant amount of the screen and, hence, there is much overlap

Render-to-texture (RTT) render to image first i.o. rendering to screen

drawback: background is flattened

RTT for strokes that have been drawn completely and need not to be animated anymore do this for every 10-20 new strokes Consistent frame rate of 60 fps