You can find out more about the visual modeling of requirements by exploring the resources below:

• Tools
• Papers

Tools

• Enterprise Architect (Sparx Systems) with optional plugins: MDG Link for DOORS & RaQuest
  • Enterprise Architect is an award-winning UML modeling tools that adds exceptional value by extending UML to support Requirements diagrams that allow users can create and manage visual requirements directly in their UML model.  Since requirements management is built into the core product, EA provides excellent support for requirements tracking, change management, and team development. Although the RM support built into EA is comprehensive, there are two plugins available that provide extra capabilities:
    • MDG Link for DOORS plugin provides a lightweight bridge between EA and one of the market leaders for traditional RM tools, Telelogic DOORS.
    • RaQuest plugin. Provides a large number of enhancements for managing and tracking requirements.

    Free trial versions of all products are available for download and evaluation.

• RAVEN Professional (Ravenflow)
  • RAVEN automatically converts Use Case text descriptions to UML diagrams, making it easier for business analysts to detect errors and validate their requirements. A flash demo and white paper are available on their web, but no free trial version is available for download, and no pricelist is published.
• Visual Use Cases (TechnoSolutions Corporation)
  • Use Case authoring and diagramming tool. Although not as powerful as RAVEN Professional, it is priced as commodity software and offers a free trial version for evaluation.
• DOORS/Analyst (Telelogic)
  • A visual RM tool (Telelogic DOORS) that integrates a UML modeling environment (Telelogic TAU G2). This tool keeps textual requirements and visual models synchronized, ensuring consistency and traceability of requirements. Basically bundles two complementary products which you can purchase separately. However, the advanced and costly code generation features of TAU are not provided with this bundle.
• Visual Requirements (Lucid Modeling)
  • A visual requirements development tool that supports requirements elicitation, formalization, analysis and management with both graphic and text representations.
• Serena Composer (Serena)
  • Composer is a visual requirements definition and prototyping tool that helps business analysts communicate their requirements to software developers.
• iRise Manager (iRISE)
  • Visual requirements management tool that documents, manage, trace and validate requirements in the context of application simulations.

Papers

• Visualizing Requirements in UML Models, Sascha Konrad, et al., Requirements Engineering Visualization 2006 (REV '06), Sept. 2006, pp. 1-10.
• Model-Driven Visual Requirements Engineering, Helge Solheim, et al., 13th IEEE International Conference on Requirements Engineering (RE'05)   pp. 421-428