Ecology is a challenging application area for mobile service robots. They should be able to automate tasks that are too tedious or dangerous for humans to execute, such as collecting waste material. Such a robot must make use of several senses, of which the most important and difficult to implement is vision. This paper presents the cognitive vision system of ReMaster One, an autonomous service robot that is able to recognize and sort waste in an indoor environment. A first prototype has been built and tested with success.