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Navigation of Virtual Reality Tutorial

(VRML and X3D)

VRML leading to X3D is a another triumph of those who work to create and maintain a standardized interface to an otherwise very esoteric capability, therefore bringing an important means of expression and potential income to the widest possible range of content creators and otherwise common persons.

Of course, you want all the hardware graphics acceleration, memory, and cpu speed (in that order) you can get.

If jumpy, reduce window size. It may increase smoothness of motion as you change your viewpoint or objects in the scene move.

While VRML/X3D is a relatively new addition to the WWW, aspects of realistic 3D UI is rapidly being assimilated into interactive applications. VRML/X3D allows a web designer to program in a truely 3D environment with an ease similar to that of advanced HTML/XHTL. There are several economical "drag and drop" scene editors, you can easily resort to a simple text editor to make additions and fine adjustments, and generally all modern computers will render VRML and X3D pretty much the same.

VRML and X3D user code is Almost Always a separate file, opened either directly as a .wrl file, like

http://www.hypermultimedia.com/JOESG/hmmJoesGarage.wrl

which will give you a full-window view of the scene, or as an object embedded in an .htm page, like

<p align="center"><embed src="../JOESG/hmmJoesGarage.wrl" align="baseline" border="0" width="800" height="600" ></p>

which will display the VRML scene similar to the way an ordinary .gif or .jpg is presented except a lot better.

If you think the the scene has finished loading (no link activity for 5-10 seconds) and a black screen is displayed, try to get a right-click Context menu. If an error was detected, an error console may be displayed. Finally, try using Refresh or Reload.

Depending upon the scene content, the loading process may go on and on. Even though X3D geometry and animation is very efficient, other types of files like sound and other artwork may be loaded along with the scene. I must beg for patience as this loading takes place. Because X3D provides the author with interfaces to control and monitor the loading process, a considerate author will provide some interesting content while any large content is loading.

A convenience is that after you have loaded the scene, you can usually view it off-line.

First try pressing PageDown and PageUp keys. These are the standard keys for moving to the next or previous viewpoint, respectively. Don't be alarmed if the scene suddenly shifts when you press one of these keys. The scene is changing because the viewer (the virtual you!) is moving from one predefined point of view to another. Various X3D viewers may provide other choices, such as buttons on a viewer control panel.

The courteous author has provided several points of view - hopefully in a sequence that guides you through an overview of the content. I suggest you take that tour now, jaunting from one viewpoint to the next until you arrive back at the initial viewpoint.

Some presentations will provide a control area including a View or Home button. Use the pointing control and left-click to select the next or previous viewpoint.

As another method, use a Context menu. Move the cursor to any part of the scene and press the right mousekey. If a menu appears, select VIEWPOINT. Select Next or Previous, or any viewpoint name or number in the list.

The thoughtful author has predefined a navigation method - Walk, Fly, Pan, Roll, Slide or Examine - at each viewpoint, so now find out what method of navigation has been selected.

Your host computer is using some specific application to present this scene, and each application may have a certain set of symbols to show you what the current navigation method is. Still, the best method for you to use is to just try it.
Besides, the author may have been able to define the optimum first navigation type at each viewpoint so that you can best free navigate to comprehend and use the information content.

If you get lost, just use the viewpoint selection process to get to a recognizable point, then try again.

If the scene changes, you are controlling some movement of the current viewpoint and thus changing your view of the scene. Depending upon the current navigation type, this moves your viewpoint orientation or position in some combination of x,y,z,w coordinates within the scene.

If you move the mouse too far or too fast, you may seem to lose control. In general, the farther away the cursor moves from it's position when you first clicked, the faster the navigation will take place.

If the author has pre-selected Walk you will generally follow the surface of the terrain. Moving the pointer up/down moves forward, while relative left or right controls the viewing direction and thus the direction of movement. In general, you will move in the direction you are looking. Just move the pointer left/right to look around, and up/down to move. Your movement may be affected by 'collision' with objects in the scene.

If you get lost, just use the viewpoint selection process to get to a recognizable point, then try again.

Fly typically eliminates the gravity effect and allows you to move in any direction without restriction, except collision. As with Walk, pointer up/down will move forward/backward and relative left/right will cause the view to yaw in the desired direction. Other controls are used to provide pitch and roll movements tp aim the view in the direction you wish to travel. Note that the arrow keys will provide movements appropriate for the selected navigation.

So, with this set, without moving the mouse:

If clicklock does not seem to work, try it again slower, or move the the marker farther, then stop. Important steps are to hold the key down, move it a short distance, stop the movement, hold the key down a little longer with no movement, then release the key.

If clicklock works, you may now move the mouse in any direction and free navigation will take place without the need to hold down the mousekey.
Use a short left-click to stop navigation.
This technique is easier for me, because I can control the mouse motion better if I don't have to hold down the key.

If clicklock won't work, you will hold the left mousekey down continually as you navigate. When you release the key, navigation stops.

Not to neglect the obvious, you can probably also use the Up, Down, Right, and Left arrow keys to navigate with movements appropriate for the selected navigation.

With this knowledge and skill you can select different viewpoints and free navigate at each of them. I suggest doing a quick scan and brief navigation at each viewpoint so that you can get a better idea of the scope of the content.

Right-click to display a context menu. Select Navigation or something similar and if a submenu appears, you get to select a different method of free navigation. You might be already able to Walk or Fly, and now you can select other methods like Pan or Roll.

Walk generally follows the surface of the terrain by providing the effect of gravity. Moving the pointer up/down moves forward, while relative left or right controls the viewing direction and thus the direction of movement. In general, you will move in the direction you are looking. Walk is the simplist form when the author has provided terrain for you to walk on. Just move the pointer left/right to look around, and up/down to move. Your movement may be affected by 'collision' with objects in the scene.

If you get lost, just use the viewpoint selection process to get to a recognizable point, then try again.

Fly typically eliminates the gravity effect and allows you to move in any direction without restriction. To move in a desired direction, you first aim the view in the direction you wish to travel. As with Walk, pointer up/down will move forward/backward and relative left/right will cause the view to yaw in the desired direction. Other controls are used to provide pitch and roll movements.
Slide moves the view right or left for Walk and right/left/up/down for Fly. This movement is useful for gettin around collidable objects.
Pan will allow you to look all around the scene freely without changing your position. When you select Walk or Fly, then you can move in that direction. For Fly navigation, you may use Pan to change your heading and pitch, then return to Fly for movement.
Roll rotates the view around your view direction. This is not usually useful in Walk, but is usefull in Fly to change your 'up' when choosing movement direction.

Those are the typical basic movements available to the author and the user. The browser will also provide some set of keystrokes or a menu to make it easier to switch between the various navigation types.

In addition, the X3D browser will include a couple of navigation utilies: Examine which allows the viewpoint to move around an object, and LookAt which allows selection of the object to examine.

For example, use Pan to look around the scene for an object of interest. Select LookAt. Now move the pointer over that object and left-click. The viewpoint should move toward the object with the object in the center of view.
Select Examine. Pointer movement causes the viewpoint to move around the object at a fixed radius while keeping the selected object in the center of the view. Repeat the LookAt process to get closer, or selt another object.

Basic navigation relies on basic controls. To Walk, for instance, the mouse relative x,y position is employed for two elements of navigation. First, forward/reverse speed, and also left/right view and thus movement direction. We are trying to move in 3D x,y,z space with a 2D x,y control. This means that if you Walk toward an object in the scene, you cannot turn away and still be moving toward that object. You will be moving toward the object you are looking at.
Does this mean that you cannot Walk and Roll simultaneously? Yes, but you can Walk and then Roll and then Pan and then Walk again.
In fact that is what you will probably be doing in order to get to all points of interest in the scene.

This is different from 'Game' style navigation where interdependant actions using multiple sets of controls allow one control, for example a mouse, to control the view direction, and other controls, like maybe one or more sets of keys, to initiate/sustain movements.

The X3D browser you are using may allow selection of a GameWalk navigation, or GameFly navigation will use multiple sets of controls for gaze direction and the various available movements.

Depending upon the host application, these choices of navigation type may be easier or harder to make.
Depending upon the author's skill in content presentation, it may be easier or harder to select and then control the various navigation types and utilities so that you can locate and interact with the content.

My favorite is Pan. From the current viewpoint you can use Pan to scan the entire scene. Unfortunately, the author may not have had the opportunity to define Pan as the default method, so I suggest selecting it now.

My next favorite is LookAt. Select LookAt then just center the cursor on the object you wish to view and press the left mousekey momentarily. Your viewpoint is moved to a convenient viewing distance away from the selected object.

Without pressing the mousekey, move the cursor around the current scene. You may see that as the cursor moves over an object or area it changes shape and a notation will appear somewhere on the display that shows a description of the object or area and possibly the words Goto followed by name of the target link.

If the target name has the # symbol preceding it, this is a link to another viewpoint in the current scene.
This indicates that the author has provided a tool I am calling the HyperViewPoint.
If you position the cursor over the object and left-click you will be moved to a new viewpoint in the scene.

You may notice that if the cursor was over a hyperlink embedded in the scene, the cursor changed to a different symbol, (hopefully the same as when you are over a hyperlink in a .htm show) and a notation will appear somewhere on the display that shows a description of the link and the name of the target link.

If the target name has the words Goto preceding it, with no # symbol, this is a link to another url outside the current scene.
If you press the left mousekey momentarily the hyperlink is executed. taking you outside the current scene to another 2D or 3D scene.
What you do then is up to you, but hopefully you can always select Back.

Of course there is a ton more of stuff to learn about the relatively simple topics of viewpoints and navigation (including possible ctrl and alpha key combinations), but I hope this will help get you started.


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