Over the last few years, a number of vision or optical systems became commercially available to determine particle size distributions of ore or other material on a conveyor belt, or in some cases at the discharge of a truck or even in a pile in some cases. Most such systems were designed as standalone measurement devices, which generate information for the operators or for an independent control system. The VisioRock system is innovative both from the hardware and software point of view. It is based on the USB technology although it can use either analog or industrial USB cameras-and the software is integrated within the vision module of the OCS(C) advanced control software. It is possible to install VisioRock cameras at many different locations in a comminution circuit, which interact with the control system and help to increase plant performance. The paper describes the VisioRock technology and some of the possibilities which result from its integration with OCS(C). For instance, in addition to measuring the particle size distribution of solids, VisioRock can determine texture and color separately for each size class, discriminate between ore types and size distribution for different type of particles, and ability to seamlessly combine image analysis algorithms with other artificial intelligence tools such as expert systems, fuzzy logic, neural networks or phenomenological process models. (C) 2004 Elsevier Ltd. All rights reserved.