VRweb Navigation Techniques

# Navigation Techniques

## Navigation Modes

VRweb offers 5 modes for navigation in scenes, each of which is described on its own page. The mode can be selected by pressing the appropriate button in the toolbar, via the Navigate menu, or by using shortcuts.

- Flip (accelerator key F4)
  is used for examining objects, whilst the viewer remains stationary.

- Walk (accelerator key F5)
  is used for strolling through a 3D environment.

- Fly (accelerator key F6)
  is like piloting an aircraft.

- Fly to (accelerator key F7)
  is a tool for controlled approach to a point of interest.

- Heads Up (accelerator key F8)
  is an easy to use navigation method for moving around in a scene by use of control icons.

## Viewpoint Control

- List of predefined viewpoints

  VRML offers the possibility of multiple predefined viewpoints. You can select one of them in the Viewpoints pullright menu. After you select one, its name is also displayed in the status line. Up to nine viewpoints can be accessed via the accelerator keys 1 to 9 (digits). The initial camera always has number one.

- Reset View (accelerator key r)

  This is your "emergency exit" if you get lost in hyperspace. Select this function and you will be brought back to the initial view. In case of multiple viewpoints you go back to the most recently selected one.

- Level View (accelerator key l)

  This function makes your view parallel to the ground plane, i.e. shows a view where you are no longer looking up or down or tilted.

- Untilt View (accelerator key u)

  This function makes your view untilted. If you wish to explore worlds without ever tilting your head, you can control this with an option (see below).

## Navigation Options

- Enable Motion with Anchors

  When turned on, you can still navigate when anchor highlighting is turned on. You have to double-click (or ctrl-click) anchors to activate them in this case.

  When turned off, you may activate anchors with a single mouse click when highlighted, however, navigation is disabled in this case.

- Velocity Control

  When enabled, mouse draggings in walk and heads up mode correspond to speed changes, which gives very convenient control. When disabled, draggings are directly mapped to motions.

- Free Rotation Control

  This allows you to tilt the view of the scene or the scene itself when enabled. Disable it if you wish to keep an upright view.

- Collision Detection

  With collision detection activated, you are prevented from "flying through walls". This imposes a small computational overhead, but gives a much more realistic feeling while exploring virtual worlds. You will also notice that you slide along walls when approaching them on moving forward/backward (you won't just stop).

## Navigation Settings

This dialog allows setting of various navigation constants. Use the sliders or field editors to change the settings. Press the OK button to accept the new values. Use the Reset button to return to the default settings, and the Cancel button to restore the previously set values. The Help button brings you to this help page.

- Collision Distance

  This is the distace you are kept away from objects when collision detecion is turned on (see above).

- Navigation Speed Factor

  This value allows an overall acceleration or deceleration in all movement metaphors. It represents a factor multiplied to your mouse movements. On fast machines you may want to decrease this value, on slow machines or large scenes you may want to increase it.

- Fly To: Zoom Speed
- Fly To: Rotation Speed

  These two values control the speed in mode fly to. They represent the fraction of motion towards the point of interest per frame. It is recommended to set the rotation value a bit larger than the zoom value to get an appropriate motion curve.

## Spaceball Control

Note: Settings made in this dialog are only effective when you have a spaceball connected to your machine. Spaceball support is currently compiled into the SGI binary and available in the source code. If you have a spaceball connected to another machine, please compile the source code yourself or contact the VRweb team.

Spaceball buttons 1 and 2 toggle Translation and Rotation. Button 3 toggles the Single Axis Filter, performing either a translation or rotation along the dominant axis (recommended for beginners). The spaceball device will beep on turning on any of these options. Note that the buttons have no effect when no scene is currently loaded.

Button 4 switches between the flip and walk metaphor. The first one manipulates the object, the second one controls the viewpoint in the scene.

Buttons 5 to 7 control the sensitivity, which is also displayed in the dialog. Button 5 halfs the sensitivity, button 6 doubles it, and button 7 resets it to the default value.

Button 8 rezeros the spaceball. You can also achieve constant motion by twisting the spaceball, pressing button 8 and then releasing it. Press button 8 again to stop.

Finally, the push button P on the back side of the ball resets the view.

## Browser Control

- Back (accelerator key b)
- Forward (accelerator key f)
- History (accelerator key h)

  These functions are passed to your web browser.

- Hold (accelerator key H)

  This function of the Navigate menu is used to hold the current window. I.e. the current scene is prevented from being replaced by another one - even when you configured VRweb to use a single window for successive scenes (remote call).

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