Flow charts are widely used in gas industry. They record parameters of a gas flow (like pressure) on a paper disc. This data is then used to calculate gas volume passed through a pipe.
The chart recorder contains two or three pens driven by sensors. These pens plot traces on a rotating paper disk. The disk performs one revolution per day or week, rarely per month. The disk is replaced after one revolution.
Currently disks are processed manually. The operator uses the vector graphics editor to convert the scanned bitmap to contours and then to tabular data. This approach relies heavily on the operator’s attention and experience. There is a high probability of mistakes. After all, such job is really boring!
We have developed an algorithm that performs this job automatically. Given a bitmap with a scanned chart, it produces tabular representation of chart data.