1. 3D terrain management tool

3MAP - milestone 2.

interaction design : principles : navigation

Design Principles

Navigation in the Virtual Reality geospatial enviroment



Humans live in three dimensions, but navigate in two. Gravity constrains us to the ground plane.

Generalised VR navigation systems typically allow unconstrained movement in three dimensions, leading to user disorientation [Clarke-Willson, 1998].

Flight is problematic; humans need training to navigate in three dimensions. Unless performing aerobatics, even pilots navigate in two dimensions, constraining themselves to level flight. Changes of altitude are considered as separate manæuvres from two-dimensional steering.

It is important to provide a simpler navigation system in order to facilitate non-expert use of the system.



Lessons from game design show us that navigating 3D space can be simple and effective if users are given appropriate affordances and constraints.

Therefore: constrain navigation to two dimensions. Change in altitude should be accomplished with a separate control.

Task flow

Proximity to the planet is closely linked to user task flow. The following modes are being developed:

  1. High Orbit. Rotate globe to select an area of interest.
  2. Satellite. Nadir-facing (looking straight down), users can move across the surface of the planet.
  3. Aerial. Corresponds to aerial photography. Nadir-facing with lateral movement. This mode is appropriate for locality-based information seeking.
  4. Flight. Like a low-flying helicopter. Initially facing diagonally down, but with control of view angle, users can fly at a constant height above the ground. This terrain-following flight view is appropriate for exploring the environment, selecting nodes for detailed information discovery, and placing geometry.
  5. Walk. Viewpoint is at eye level, and now faces horizontally. Lateral movement follows terrain, simulating gravity. Vertical motion that mirrors real-world constraints has been shown to increase immersion in game worlds. A slight bobbing up and down of the viewpoint during forward movement simulates the motion of walking, and also provides extra occlusion and parallax cues, heightening the 3D feel.The availability of a Jump button has the same effect.




From orbit, the view frustrum (in yellow) is locked to the centre of the Earth. Navigation is constrained to the orbital sphere. Following the standard set by PC games, movement can be controlled with the mouse, with the cursor keys, or with the numeric keypad.


At any point the user can zoom up or down a vector from orbit toward the earth's centre, terminating at the planetary surface. The view snaps to logical positions along the vector, with a single keystroke to zoom from high orbit to satellite to aerial view (Z zooms in, A zooms out). At any given altitude, navigation is constrained to that altitude.


From aerial, the user can zoom down to flight view, and then down to walk mode. During this stage of the descent the view angle automatically tilts up from vertical (nadir-facing) to horizontal.