Fluid Sketches: Continuous Recognition and Morphing of Simple Hand Drawn Shapes

-Arvo, Novins

COMMENT

SUMMARY

In this paper a new sketching interface is described in which in which raw geometrical strokes are continuously morphed into ideal strokes. The recognition is performed by using least square fits or recognition. The main aim of the authors is to provide immediate and useful feedback. The authors claim that such type of feedback allows users to be sloppier and still gets their sketches recognised correctly.

The authors formulated a family of differential equations that determine how a user drawn shape changes with time due to continuous recognition and morphing. This parametric ODE is referred to as the fluid sketching equation. The shape of the morphing curve may be influenced by many factors in the equation. At each step the algorithm finds the best match within a family of shapes. Different techniques are used for matching to different shapes. For example to fit the curve to a circle a linear least squares method is used, and a relaxation technique is used for fitting the curve to a rectangle.

The system was tested with users who were are graduate students. Each user was asked to reproduce a previously drawn sketch using conventional sketch system and the fluid interface system. The users favoured the conventional system to draw accurately placed shapes but favoured the fluid sketching interface strongly when they had to draw approximately placed shapes. Users also felt the need to have editing features which are currently absent in the system.

DISCUSSION

The main contribution of this paper is the evaluation of an immediate feedback sketch system. Several advantages and shortcomings of the fluid sketching system are studied. One of the problems with the evaluation is that the system was studied on just two types of recognizable shapes - the box and the circle. It remains to be seen how the system would behave with multiple shapes in the domain. System might have to match the drawn stroke to each shape in the domain as each pixel of ink is drawn. This might be computationally expensive.