(5303) Pen Stroke Recognition
Michael Howard , Derek Lee
East Northumberland SS



Abstract


In the twenty-first century computers have become an integral part of everyday life, however much of the computers usability is rooted in the way humans can interact or interface with them. Input devices such as the mouse and the keyboard are widely accepted, although many other input devices could be used to both increase performance of certain applications as well as generate new programs to further broaden computer horizons. The purpose of this project is to create a writing program which will convert signals from an infrared pen into computer text.

The basic principle of our pen stroke recognition software is that every letter is made up of a series of lines each with a sequence of general directions. Because computers are based on the use of precise numbers, they must be programmed to convert precise numbers into general directions. This can be done using a coordinate grid and vector math. The coordinate of (0,0) is located in the top left hand corner of the screen. The use of this grid allows us to determine the general horizontal, vertical and diagonal directions of a drawn line by finding two points on the line and finding the difference. While this is good for very general directions there is one problem. Due to the fact humans are not nearly as precise as a computer, they cannot consistently draw a perfectly horizontal or vertical line. Because of this, code needs to be written to compensate. However human error cannot be compensated in this form. Because lines can be drawn different sizes and a coordinate based exception such as an x value between 20 and +20 would not work. If the user drew a horizontal line with a length of 10, the computer would ignore it. The solution lies in the use of unit vectors. By taking the line and reducing it to a single unit direction (its still a number) we can create a generalized exception that works for any line as well as accurately determine the direction of the line.

The second aspect of the program converts the general directions, which are stored in an array of Boolean (true or false) data types into characters. Any letter in the English alphabet can be created using a four pen strokes. The standard model for our program is that four sets of directions are stored and once the four set is received the program compares both the order of the directions and the directions themselves and generates the matching character.

In conclusion, the use of this technology can be used as an alternative to a mouse and keyboard. Due to the portability of a pen and the inexpensive cost of infrared technology it is entirely possible that more portable, cost-efficient laptops could be created. Similarly the pen also has added functionality as it increases the ease at which the user can informally jot down notes as well as its potential is for further technologies, such as computer art, and computer whiteboards.