Functional requirements are often written using use cases formatted by textual templates. This textual approach has the advantage to be easy to adopt, but the requirements can then hardly be processed for further purposes like test generation. In this paper, we propose to generate automatically through a model transformation an activity diagram modeling the use case scenario. Such an activity diagram allows to guess in a glimpse the global behavior of a use case, and can easily be processed. The transformation is defined using the QVT-Relational language, and is illustrated on a case study using a supporting tool.