6B-3-2 
sensor or some other sensor technology, by 
reason of the special design with some special 
mathematical serials. But it is very difficult for 
the users to confirm the heights simultaneously; 
due to they can not decode the “bar-code’' 
pattern to the naked eye. So they worry about 
the results is the way of the world and is 
understandable. The question is that how to 
dispel user’s misgivings in the surveying at the 
moment, and how to measure the heights with 
the conventional straightedge or the staff, and is 
possible to beyond naked eye vision with the 
help of robot vision or computer vision for the 
leveling and distance measurement. Our aim is 
try to resolve these problems and will give the 
“measuring” a new life. In this paper, the basic 
idea and algorithms related to software of the 
automatic straightedge recognition system was 
introduced. It will be include following parts: 
(1). The flowchart of the automatic recognition 
system.; (2) FFT method to compute distance 
and to determine the pattern position in the 
straightedge; (3). Character cutting and global 
matching to compute the height. (4). Evaluation 
and discussing. 
1. THE FLOWCHART OF THE 
AUTOMATIC RECOGNITION SYSTEM 
The main purpose of the system is to obtain the 
height of the straightedge with the help of 
image processing technology and machine 
vision. For the conventional straightedge in the 
market, there are many kinds of patterns for 
measurement. Most of them using Arabic 
■numbers to distinguish the length together with 
some designed patterns. This report is try to 
automatically recognize the Arabic numbers 
and then to compute the length (height) with 
the help of the special designed patterns based 
on some kind patterns. 
The flowchart of the two dimensional 
automatic recognition system could be shown 
as Figure 1 as below. 
Figure. 1 Block Diagram of two dimensional automatic recognition system