Vision Based Liquid Level Detection and Bubble Area Segmentation in Liquor Distillation

In order to automatically measure the flow rate, alcohol strength and roughly determine the quality of distilled liquor, a system was developed with two transparent standard containers, two load cell sensors, and a camera. This paper presents the imaging part of the measurement system, including the optical path as well as a set of image processing methods to detect the position of the liquid level and calculate the amount of the bubbles on the top of the liquid. Four ArUco markers are used to locate the containers in the captured image and the containers are cropped out. Then the liquid level is detected and the area of bubbles are segmented using statistical information of the pixels in each container. According to the test results, the proposed methods archive accurate and real-time detection on an embedded processor and is robust to the change of the illumination, flowrate, liquid level and camera position.