Analog dial gauge reader for handheld devices

In a typical process industry, there are several critical dial gauges wherein the readings are to be monitored on a periodic basis. Most of these dial gauges are still analog in nature and currently these are being monitored manually. The manual capture of readings is a tedious task and is also prone to error. This paper outlines an algorithm that can automatically identify the dial gauge readings using image captured by a PDA device. This will help in reducing the error in readings as well to provide a record of the actual reading for future reference. Our algorithm uses polar representation of the dial gauge image to identify the needle position as well as the start position of the dial gauge. Once these are obtained the reading of the dial gauge can be estimated with prior calibration information. The algorithm was tested on multiple dial gauge images captured in a local chiller plant and is shown to obtain the readings reliably in about 95% of these images.