Three-dimensional reconstruction for high-speed volume measurement

Volume measurement is an important process for various industries such as food processing, fruit and vegetable grading, etc. Value or price is often determined by the size of product. In seafood industry, for example, oyster meat is separated into four grades before being packaged. Large size grade means higher selling price than small size. More consistent packaging size is also an indication of high quality. Product size can be measured optically with machine vision technology for on-line inspection and grading systems. Most optical grading techniques use a two-dimensional area projection or the weight of the product to estimate the actual product volume. These methods are subject to measurement inaccuracy because of the missing thickness information. An algorithm combines laser triangulation technique with two-dimensional measurement to reconstruct a three-dimensional surface for volume measurement is introduced in this paper. The result of this technique shows a significant accuracy improvement from the area-projection method.