Designing with a 2½D attitude

Computer graphics gives us freedom to design highly interactive 3-D information spaces, but when will these be better? An analysis of human space perception reveals that the dimension of egocentric space towards and away from an observer is perceived very differently from the dimensions orthogonal to the line of sight. Because of the this property of perceptual space a strategy of designing with a 2½-D attitude is advocated and elaborated in a set of design principles.