cylinder is a camera controller, whichcontrols the position and directionof the first-person view shown on theextra display. By moving the cameracontroller, users can stroll through thefully rendered 3D world. The secondcylinder is a color controller, whichcan change the color of the facade ofa building when it is placed next to abuilding cuboid. The third cylinder isa time controller, which controls thetime of day in the virtual world. Thetime controller also functions as a dialthat controls the lighting conditionsas the sun or moon moves acrossthe virtual sky and illuminates thebuildings, which in turn cast shadows.The tangibles can be employedsimultaneously, which allows multipleusers to collaborate on positioningbuildings, try out different colorvariations, and see the first-person viewat different times of the day.
In the case of Tangible Urban Planning,3D projection was employed to visualizeand explore large-scale urban planning.In a supplementary study, we developedthe Tangible Blueprint installationto further examine how this form ofinterface could support architecturalplanning on a smaller scale. A blueprintof a planned building is displayed on thetabletop, while a rectangular tangibleperpendicular to the tabletop offers a3D view into the building. This enablesusers to experience the 3D model of thebuilding, complete with surface texturesand lighting, in real time (see Figure 4and [ 9]). In contrast to the camera viewin Tangible Urban Planning, whichwas displayed on an external display,the view into the 3D world here isdisplayed directly onto the tangible.When the tangible is moved, theperspective changes correspondingly.The tangible thus acts as both an inputdevice (controlling the camera view)and an output device (showing theviewpoint in the 3D world). This systemalso supports multi-user interaction.By placing multiple tangibles on thetable, multiple users can exploredifferent portions of the building at thesame time, and different tangibles canrepresent different aspects, such as dayand night-time views and X-ray views ofwiring and tubes hidden in the walls.
Projected Play was custom-developedIFigure 3. Tangible Urban Planning.