Teixeira, José CarlosRix, JoachimMadalena Quirino2023-03-092023-03-092023978-3-03868-204-2https://doi.org/10.2312/pt.19881537https://diglib.eg.org:443/handle/10.2312/pt19881537The User Interface plays a very important role in the geometric modelling systems. Different approaches have been developed in the last years, with and without the use of graphic images. As the sight is the most important human sensory, more and more efforts have been made to design effective and powerful graphical ori- ented User Interfaces. Starting with general issues and guidelines for graphical User Interface design, the paper reports the DACAD User Interface approach. DACAD is an experi- mental system that uses the methods of the constructive geometry and the technical design knowledge as a basis to create and manipulate three dimensional models.Attribution 4.0 International LicenseUser Interface, dialogue, computer aided design, modellingUser Interfacedialoguecomputer aided designmodelling10.2312/pt.19881537