Scientists at the University of Edinburgh in the UK have developed interfaces based on real objects, such as sheets of paper, and interaction modalities fashioned on projected virtual characters, namely animals that crawl on walls, to enliven participation at business meetings and for use in creative industries and exhibitions. Through the 'Natural interaction with projected user interfaces' (NIPUI) project, they have created controllable projection units for the projection of virtual documents on to real paper. However, having succeeded in building a prototype of such an interface, it quickly became clear that the resolution of the projectors used was not sufficient to be able to project documents as virtual sheets of A4 papers in a way that they were readable. They have since improved this design by using a high-definition projector in a second prototype. The Edinburgh team also looked at enhancing projected user interfaces to allow virtual characters to be projected on to room surfaces. They believe that virtual characters can provide a 'novel, powerful and fun' user interface, in particular when combined with speech technologies. Therefore, during the project they developed a system that allows them to model the room as a set of surfaces representing the physical surfaces on which the characters live. They used cartoon versions of animals that can crawl on walls - geckos in particular - as characters, and to further increase credibility, they simulated their motion, in particular that of their feet, on the surface. To let the character 'talk', they used speech synthesis which means the character's lips move synchronously with the speech output. They also used a hypersonic sound speaker, which is a directional speaker system which can be described as a spotlight for sound, to make the sound seem to appear from the character's mouth.