Reading #15

Comments:
 Yue

Summary:
This paper has proposed an image-based method, which follows vision ideas. In this method, the sketch is compared with a 48 by 48 bitmap image. This algorithm is similarity transformation- invariant, and fast. It needs to mention about the rotation. They first transform the symbol image into polar coordinates and mapped into [-pi, pi] range. In polar coordinate they can easily calculate the rotation angle and again transformed into screen coordinate to continue their recognitin.  The whole system is instances-based, so it is easy to add/remove already-defined class.

Dicussion:
It is a clever idea to convert the sketch into an image, so that all the algorithm related to vision ca be applied. However, I am pretty surprised about the speed. Since I assume the convertion from sketch to image might be slow, even though they can solve the rotation efficiently.