Visualization is a technique for creating a graphical representation of a reality, with possible augmentations. It can be used in a wide variety of applications in the area of robotics. An example usage is for teleoperation, where a human operator can control a robot from a different location by having the robotic process visualized in real-time. Furthermore, visualization software can also be used for doing detailed analysis of a process, for instance to debug a system that is under development.This thesis proposes and implements a system that visualizes robot cells in 3D. The system presented here uses RViz as the actual visualization program, and Robot Operating System (ROS) to connect the different parts of the system together. In all, the system is organized in a way that makes it easy to combine several different robots and other devices in one view. The main part of the system presented in this thesis is a Graphical User Interface (GUI), which is used to control the actual visualization, as well as the rest of the system. This GUI provides functionality to record and play back measurement data from the different devices and sensors, making it possible for a human operator to pause, resume and step through the data one value at a time. To be able to use this general system on a real robotic process, it has to be customized by specifying the available devices, and information about these, in a configuration file.The developed system was tested on the Ekornes sewing cell at SINTEF Raufoss Manufacturing. The sewing cell consists of a sewing machine and two industrial robots, that are used for sewing together leather covers. Based on this testing it was seen that the program is a powerful tool for analyzing robotic processes, because of the possibility to record and replay data, as well as providing the operator with a very informative visualization view.