Figure 3. SandScape. Users alter the form of the landscape model by manipulating sand while seeing the resultant effects of computational analysis generated and projected onto the surface of sand in real time.

 

ble representations of digital models of the buildings. To change their location and orientation, users simply grab and move the physical model, rather than a mouse, to point to and drag a graphical representation on a screen. The physical form of Urp’s building models and the information associated with their position and orientation on the workbench represent and control the state of the urban simulation.

Although standard GUI interface devices (such as keyboards, mice, and screens) are also physical, the physical representation in a TUI provides an important distinction. The physical embodiment of the buildings (representing the computation in building dimensions and location) allows for the tight coupling of control of the object and manipulation of its parameters in the underlying digital simulation.

In Urp, the building models and interactive tools are physical representations of digital information (shadow dimensions and wind speed) and computational functions (shadow interplay). The physical artifacts also serve as controls for the underlying computational simulation (specifying the locations of objects). The specific physical embodiment allows dual use in representing the digital model and the

control of the digital representation.

However, Urp lacks the ability to change the forms of tangible representations during user interaction. Users must use a predefined finite set of fixed-form objects (building models in this case) and change only the spatial relationship among them, not the form of individual objects. All tangible objects in Urp must be predefined (physically and digitally) and are unable to change their forms on the fly. This is why the Tangible Media Group designed the second generation of “organic” TUI.

 

SANDSCAPE: SECOND-GENERATION TUI

The advent of new sensing and display technologies made it possible to add dynamic form development into TUIs, suggesting movement toward new digital/physical materials that seamlessly couple sensing and display capabilities. Rather than using predefined discrete objects with fixed forms, the Tangible Media Group developed new types of organic TUIs that utilize continuous tangible material (such as clay and sand) for rapid form sculpting for landscape design; examples include Illuminating Clay [ 6] and SandScape [ 2]. With the advent of flexible materials that integrate fully flexible sensors and displays, this category of organic TUI shows great potential to express ideas in tangible form.

SandScape [ 2] is an organic tangible interface for designing and understanding landscapes through a