THE DIGITAL ARTS

Apple's QuickTime VR: Virtual Reality on a Virtual Shoestring

Johannes Paul Lang

Virtual reality - walking through computer-generated 3D environments, manipulating imaginary or distant 3D objects - is the stuff of dreams for many a multimedia enthusiast, and almost the stuff of many computer games. And there are serioius uses for VR, as well (there will be an article on VRML, the Web language for virtual reality, in a coming issue of Connect). There are limitations, though: for the motions within the environment to be totally unlimited, either the environment has to be very sketchy, or the computer has to be phenomenally powerful. So you have to accept some limitations.

Now QuickTime VR (QTVR) software for Macintosh and Windows brings virtual reality to the home or office computer without any special equipment or extra costs. With QTVR, you can experience a 3D photographic or rendered representation of any person, place, or thing. Using your mouse and keyboard to rotate objects, you can zoom in or out of a scene, look around 360 degrees, and navigate from one scene to another. This issue has still panoramas from several examples of QTVR. One is shown below; others are on pages 18-19 and 38-39.

QTVR Panoramas

QuickTime VR scenes (also known as panoramas) can be made from photographs, video stills, or computer renderings. Most scenes are made from photographs, as they provide the most realistic images.

To photograph a QuickTime VR scene, a camera (any kind of camera that produces still pictures) has to be placed on a tripod and carefully leveled, with the center of the lens exactly above the tripod's pivot point. Then, depending on the lens you are using (any lens can be used except a fisheye lens; the results with standard 35mm cameras are pretty good, but for great VR panoramas, 15mm lenses work best), you rotate the camera and take pictures at regular increments (e.g., with a 15mm lens, you would use increments of 30 degrees).

After scanning in the pictures (or negatives), or downloading digital images if you were using a digital camera or had your photographs developed on a CD-ROM, you use special software (a program called MPW, contained in the QTVR Developer Kit) to "stitch" the single images together into a single long panorama. While stitching, QuickTime VR warps the images. Then it automatically maps the overlapping features and stitches the images together into a single large PICT file; you can then edit the image with a program such as Adobe Photoshop before creating the final QTVR scene. Warping the images makes the stitching possible, but it also creates distortion. Straight lines become curved; everything looks bent. When you open a QTVR scene, though, the QuickTime VR Player corrects the distortion, unwarping the part of the image displayed in the Player window. As you look around, the software keeps up with your movements, unwarping and displaying your view of the panorama on the fly. The player allows you to zoom in and out, and to move up and down a few degrees. You can also link more than one panorama together into a multi-node panorama.

QTVR Objects

Unlike scenes, in which you navigate one panoramic image, or several, an object is composed of a number of images each showing the object from a slightly different angle. As you turn the object or tilt it up and down, the software responds to your movements, displaying the images as a QuickTime movie. In other words, QuickTime VR objects are navigable movies. Object movies and panorama movies can be combined. In a museum installation, for instance, you might move through the space, then "pick up" an object and turn it while you examine it.

Availability

The software for playing back QTVR movies is free. You need to have QuickTime installed on your PC or Mac, and you have to use a small utility program (QTVR Player) to watch the movies on your machine. All the software can be downloaded at no charge from the Web at http://quicktime.apple.com .

At same Web address, you can also obtain free software tools to create QTVR object movies and to transform a panoramic picture into a QTVR scene. If you get hooked and want to progress to advanced QTVR creations, though, you will need to purchase the QTVR Developer Kit, available from Apple Computer. [ C ]

About the Author
ic@nyu.edu

Posted 2 October 1996