This simplifies the interaction drastically. Aside this, we present some higher-level tools that enable the animator to locally and globally control user selected parts of the drawings. The first is used to create extreme poses of the character (without the restrictive inconveniences of standard ‘point-click-and-drag’ metaphors), while the latter is employed to provide for frame-toframe coherent animation. To establish these goals we first break down the traditional drawing process into a modelling process and an animation process. We also aim at giving the animator the same freedom of expressing the artistic style he is bearing in mind as if painting in the traditional way. We focus on eliminating the time-consuming and tedious process of drawing and managing the numerous brushes that are painted on top of each other, and on avoiding temporal aliasing artifacts such as brushes popping up in successive frames. This paper introduces new techniques and tools to draw, manipulate and animate stylised brush strokes in computer assisted animation The test results showed that the proposed method can support freehand sketching based conceptual design with no limitations on drawing sequence, directions and overtraced cases while achieving a satisfactory interpretation rate. The proposed method has been tested with our freehand sketch recognition system (FSR), which is robust and easier to use by removing some limitations embedded with most existing sketching systems which only accept non-overtraced stroke drawing.

It avoids losing joint information due to segmentation of a polyline into line-segments. This method can deal with overtraced sketch strokes in both solid and dash linestyles, fit grouped polylines as a whole polyline and simply fit conic strokes without computing the direction of a stroke. The grouped strokes are then fitted with 2D geometry. The orientation and its endpoints of a classified stroke are used in the stroke grouping process.

This method can support rapid grouping and fitting of overtraced polylines or conic curves based on the classified characteristics of each stroke during its preprocessing stage. This paper describes a new method for recognizing overtraced strokes to 2D geometric primitives, which are further interpreted as 2D line drawings.

Paper and pencil animation