Navigation

This section describes the mechanisms that the WorldView viewer provides for getting from "point A" to "point B" in a Virtual Reality Modeling Language (VRML) world. Navigating in a three-dimensional space can take some getting used to; initially, you may find some of the techniques described here more comfortable than others.

There are four parts of the WorldView window:

• The vertical toolbar, which contains buttons you use to specify how to move within a world.
• The horizontal toolbar, which contains buttons that allow you to perform corrective actions and view a world from previously defined locations.
• The viewing area, which in this picture is showing the WorldView startup screen.
• The pop-up menu, not shown in this picture, which you access by pressing the right mouse button while the cursor is in the viewing area.

Using Viewpoints

The easiest way to move around a VRML world is by using Viewpoints, which are specific locations that the VRML author has defined for you. Not all worlds contain viewpoints, but when they do, you can use them to "tour" a world just as the author has intended.

You can see a menu that lists of all the viewpoints in a world by clicking on "View" in the horizontal toolbar, or by choosing "Viewpoints" from the pop-up menu. You may move to a particular viewpoint by choosing it from either of these menus.

You may also move to the next or previous viewpoint using the arrow buttons on the horizontal toolbar. If there are no viewpoints in a world, these arrows appear grayed out.

Moving around: Walk, Pan, Turn, and Roll

Once you've gotten the hang of viewpoints, it won't be long before you'll want to start exploring on your own. This section describes the four navigation options that WorldView offers. Unlike Viewpoints, when you're navigating you control how you move by clicking the mouse and dragging in an appropriate direction. The movement that results is different for each option; it can be very helpful to experiment with them while you read this. However, there are two key concepts you should keep in mind while you're learning about navigation:

• The direction in which you drag the mouse -- from the point where you depressed the button -- determines the direction in which you move. If you change the direction in which you're dragging, the direction you're moving in will change, too.
• The distance that you drag the mouse determines the speed with which you move. If you stop moving the mouse, you'll continue moving at a constant speed until you release the mouse button.

When you select a navigation type from the vertical toolbar, your cursor will change to a shape that is similar to the icon on the toolbar. Both the toolbar icon and cursor are shown here.

Use Walk to move forward and backward along a single horizontal plane. To move forward, click the mouse button and drag straight up, toward the top of the screen. To move backward, click and drag straight down, toward the bottom of the screen.

If you click and drag upward toward the left or right, you'll move forward at an angle; if you click and drag downward to the left or right, you'll move backward at an angle.

Use Pan to move up, down, left, or right within a single vertical plane. Drag straight up to move upward, drag to the left to move left. If you drag on an angle, you'll move along the same angle.

It's important to remember that you'll move in the same direction in which you drag the mouse, which means that the world will appear to move in the opposite direction.

Use Turn to change the angle of your view. Unlike real life, you can turn upward, downward, and at other angles, in additon to left and right. To turn right, drag the mouse directly to the right. To turn downward, drag the mouse directly downward. As with Pan, you move in the same direction as the mouse, the world will appear to move in the opposite direction.

Dragging in any direction will cause you to turn in that direction. This can be confusing at first -- you might, for example, end up with the floor rotating toward you at a 45-degree angle, which isn't something we're used to in real life. Until you've gotten the hang of it, you might want to be careful to always drag the mouse directly up, down, left or right, rather than at an angle (you might find the arrow keys especially useful for this). If you've already turned at an odd angle and are now disoriented, read Getting your bearings, below.

Use Roll to rotate either clockwise or counter-clockwise within a single vertical plane. Drag the mouse to the right to rotate clockwise; drag to the left to rotate counter-clockwise. Unlike other types of navigation, vertical movement of the mouse has no effect with Roll.

 

Examining objects: Goto and Study

Goto and Study are two types of navigation in WorldView that are specifically designed to help you examine individual objects within a scene.

Use Goto to pick and object in a scene to move to. When you select on the Goto icon in the toolbar, the cursor will change to a crosshair; click on an object in the world and you'll move directly to it. If you decide after selecting Goto that you don't want to move, press the Esc key or simply click on the background in the world rather than an object.

The way that Goto works is tied closely to the way that a world was authored, which means that there can be situations where it doesn't work as you expect. Goto will always center the object that you choose on the screen. However, it's sometimes hard for you to tell how large an object is. For example, if you click on an interesting piece of architecture that turns out to be part of a single large building object, Goto will zoom your view out so that you can see the whole building, rather than just the detail you're interested in. If this happens, use another type of navigation to move close to the detail you'd like to examine.

Use Study to examine an object from various angles. Select the Study icon in the toolbar, and then click on an object you'd like to examine. Drag the mouse to see the object from different angles. With Study, mouse movement causes spherical rotation -- drag the mouse to the left to see the left side of the object; drag upward to see the top of it.

It important to remember that the object you're studying isn't moving -- you are, and your entire view of the world will change accordingly. In other words, once you stop studying an object, you might be left in an odd orientation. Read Getting your bearings below for help on quick ways to recover.

Study can be especially useful in conjunction with Goto to explore individual objects within a world.

 

Getting your bearings: ZoomOut, StraightenUp, and Restore

WorldView provides three mechansims that can help you learn your way around a world and re-orient you if you've navigated your way into an unusual position within a world. Unlike navigation, these are automatic actions that take place as soon as you click on them.

Use ZoomOut to automatically get a far-away view of the entire world. You'll move away from the world until it can be seen on your screen in its entirety.

Use StraightenUp reposition yourself so that you're view of the world is upright. Straighten Up is particularly useful if you've turned at an angle or been left at an odd orientation once you stop studying an object.

Restore automatically returns you to the position you were in when you first loaded the world. It is not the same as clicking the Refresh button in Internet Explorer, however. If there are animations or other behaviors going on in the world, Restore won't restart them, but Refresh will.

Keyboard shortcuts for navigating

Instead of clicking on the toolbar, you can use these keyboard shortcuts.

To change navigation types:

Arrow keys can be used instead of the mouse to navigate:

To perform automatic actions:

Interacting with worlds: Locating sensors and hyperlinks

As you move the cursor over objects in a world, you may see circular lines appear around it. This indicates that the mouse is over a VRML sensor; clicking will trigger some sort of interesting activity in the scene. Exactly what happens is decided by the VRML author, the best way for you to find out is to click!

The table below shows the sensor cursors for each navigation type.

Walk	Pan	Turn	Roll	Goto	Study

The actions of Goto and Study will always override sensors. In other words, if you select Goto and click on an object that is a sensor, you'll go to the object rather than activate the sensor. (To activate the sensor, click on it again once the Goto is complete.)

You may also come across hyperlinks, which may be links to other VRML worlds, specific viewpoints within the current world, or HTML documents. When the cursor is over an object that's a hyperlink, it changes to a hand:

Simply click to follow the link.

You might also come across an object that is both a sensor and a hyperlink, in which case this cursor will appear:

Clicking the mouse in this case will activate the sensor. To follow the hyperlink, hold down the Ctrl key and click the mouse.

Seeing where you're going: Using the headlight

Occasionally, you'll encounter a world where you can't really see much because it doesn't have enough light. When this happens, you can turn on a light of your own by choosing "Headlight" from the Graphics item on the right-button pop-up menu. When the headlight is on, the area directly in front of you will always be illuminated.

VRML authors can also specify the setting of your headlight, so you might find that it's turned on or off automatically as you browse among worlds.

You may use the Options dialog to change the default setting of the headlight.

Avoiding the furniture: Preventing collisions

By default, WorldView will allow you to pass through objects in your path. If the objects are large, your view of the world may be temporarily obstructed as you move through them.

To keep from passing through objects, turn on "Prevent collisions", which is located under Movement on the right-button pop-up menu. When a check mark appears next to this item, you won't be able to "share space" with objects. Instead, they block your way and you have to navigate around them.

VRML authors can also control when you're allowed to pass through objects and when you can't. You may be able to pass through certain objects even when you have "Prevent collisions" turned on.

You may use the Options dialog to change the default setting of "Prevent collisions".

Adjusting your speed

When you're navigating in Worldview, the speed with which you move is determined by the distance you drag the mouse. The farther you drag, the faster you move. You can control the way that distance relates to speed using the items under Speed on the right-button pop-up menu.

The default setting for Speed is "Medium". If you choose a faster speed, shorter dragging distances will be needed to increase your movement speed. If you choose a slower speed, you'll have to move the mouse further to increase in your movement speed. Typically this is a matter of personal preference, although novice users might find faster speeds somewhat unweildy.

Many factors determine the maximum possible navigation speed, including the complexity of the world, the image quality you've selected, and the speed of the computer you're using. The items on this menu don't affect the maximum speed, they simply determine the amount of mouse movement required to get there.