CITEC Central Lab Facilities
CITEC
British Flag   German Flag

Path Drawing

Type: Navigation
Authors: Dorothe Schneider, Sara Winter
Supervisors: Nikita Mattar, Thies Pfeiffer

Original Design

User Perspective

The original method design stems from "Path drawing for 3D walkthrough" (see reference [1]) and is an extension of the flying technique (see, for example, reference [2]). The user can specify his desired path to a target by drawing it onto the ground. The drawn stroke is then projected onto the walking surface and the camera adjusted so that it follows the drawn path. This adjustment is realised by fixing the viewpoint to the tangent of the projected stroke. This way, the user can not only specify the exact route he wants to take, but also does not have to continuously press a button during movement.

Long strokes can define a path in detail. Short strokes, however, can have two different meanings. A short stroke in greater distance will let the user reach the target in a straight line, while short strokes nearby serve to change the camera orientation. Drawing mistakes can also be corrected simply by drawing a new path.

A user study revealed that the Path Drawing technique was more intuitive and more widely accepted than both the flying and the driving method (for details on the latter, see reference [1]).

Technical Details

The only hardware information given in the original paper is that the method is operated with a display integrated tablet.

Our Realization

User Perspective

Our implementation is mostly similar to the original algorithm. A path can be drawn on the ground along which the viewpoint is dynamically adjusted in order to create the illusion of movement. Furthermore, the drawn path can be interrupted by a new path before it is finished.

The means of drawing is realised as a ray which functions as a "virtual pen"; the path is drawn at the point where ray and surface intersect. The drawn path is then represented as colorful squares on the ground which give off a small glow so that they are easily distinguishable from the ground even in darker scenes.

A difference to the original paper is that no avatar is visible on-screen in order to strengthen the user's feeling of immersion - this way, it is "he himself" who moves through the scene and not just an avatar he controls.

Furthermore, our implementation does not implement the projection of the drawn stroke onto a 3D geometry, which means that it can only handle paths drawn onto a plane.

Technical Details

The user controls his "virtual pen" with a modified version of the Nintendo WiiMote which was extended with a tracker so that its position in 3D space could be determined.

Furthermore, the implementation is compatible with a pair of 3D stereo googles, as they do not interfere with the dynamic adjustment of the viewpoint.

Evaluation

TODO

References

  1. Igarashi, Takeo; Kadobayashi, Rieko; Mase, Kenji; Tanaka, Hidehiko (1998): Path drawing for 3D walkthrough
  2. Mackinlay, J.; Card, S.K.; Robertson, C.G. (1990): Rapid Controlled Movement Through a Virtual 3D Workspace