There are a lot of criteria that you might use to choose a panorama format. One thing to keep in mind is that you might choose to create and store your panorama files in one format (such as QuickTimeVR) but choose to publish them on the Web in a different format (perhaps VRML97), just as you might choose to work with images in Photoshop's ".psd" format, but convert to JPEG or GIF before publishing them on the Web.
The following are criteria that are relevant to panoramas displayed from Web sites. Criteria that are not relevant to the suitability of a panorama format for display on the web (such as the quality or number of tools available to create panoramas in that format) are not considered. Also, only the three most popular formats are considered here; the less popular panorama formats (such as IPIX, SmoothMove, or SurroundVideo) have their own sets of tradeoffs, but, in this author's opinion, none offer a significant technical advantage.
Panoramas can be extremely large, which translates into unbearably long waits for users looking at your web site with typical modems. Live Picture and VRML97 both support storing panoramas in the standard JPEG compressed image file format, and both make it easy to store multiple panoramas in separate files. The wide availability of tools that manipulate JPEG images is an advantage over QuickTimeVR, which stores panoramas inside QuickTime movie (.mov) files. There are fewer tools available for tweaking the compression codecs that are part of QuickTime.
Both Live Picture and VRML97 support panoramas that completely surround the viewer. QuickTimeVR supports only cylindrical panoramas that have a limited vertical field-of-view-- you cannot look straight up or straight down in a QuickTime VR panorama.
Experience has shown that most people on the Internet will not download and install a special plug-in, especially if the plug-in takes a long time to download. There are panorama viewers available that are written in Java, which means that a visitor to your web site does not have to download any special plugin-- the required Java code is downloaded automatically. Live Picture distributes a Java applet that supports their panorama format for free, and gives detailed instructions on how to install it on your web site. There are also panorama viewers available for VRML97 (RubberNeck) and QuickTime VR, but it isn't clear whether these are free or not.
One drawback of VRML viewers is that their interface is designed to navigate around a complete 3D world. Because of this, their interfaces are more complicated than dedicated panorama viewers, that need only concern themselves with allowing the viewer to stand in one spot and look around. The extra functionality of a VRML viewer can make it more difficult to use.
Panoramas and 3D graphics are not yet common on the Internet, and it is difficult to get an accurate measure of the relative popularity of the various panorama and 3D graphics formats. One way of getting a very rough feeling for the popularity of the various technologies is to see how many web sites mention them; here are the results for a search using a popular search engine (Excite, as of May 12, 1998):
74,784 found, searching for VRML
16,710 found, searching for "Live Picture" or RealSpace
9,155 found, searching for QuickTimeVR or "QuickTime VR" or QTVRThe Live Picture numbers are probably inflated, because "Live" and "Picture" are common words that may be found together in contexts unrelated to the panorama technology.
VRML and Java both have a reputation for being fragile, especially on platforms other than Windows PCs. Java is still undergoing fairly rapid evolution, with Sun releasing new versions of Java every few months. Differences in Java implementations cause compatibility and stability problems for many Java applications.
VRML implementations are still being optimized and improved, and can suffer from unstable 3D hardware drivers. In general, "true" 3D graphics are much less stable on PCs and Macs than 2D graphics.
QuickTime viewers are more stable because they are all derived from the same source code (Apple's QuickTime libraries) and rely only on basic, mature 2D graphics technology.
If you want to add sound, animation, or 3D graphics objects to your panorama, then the VRML or Live Picture formats are best. Since QuickTimeVR is part of QuickTime, it is possible to integrate QuickTimeVR panoramas with QuickTime sounds and movies. However, QuickTime's limited integration with other Web technologies such as JavaScript and Java make it difficult to do this on the Web, and integration with 3D graphics is not possible on the Web.
Hot-spots are areas in the panorama that act as hyperlinks, causing some action to be performed. Live Picture and QuickTimeVR both support hotspots directly as part of their panorama's functionality. VRML has more extensive, but much more complicated, mechanisms for interaction. Adding hotspots to a VRML panorama requires a deep knowledge of VRML's interaction and scripting capabilities.
Viewers for all three formats are available for both the Mac and the PC platforms. VRML has an advantage in platform compatibility, because there are VRML viewers available for several other platforms (Linux and IRIX, for example).
VRML97 is an official International Standard, and is controlled by the Web3D Consortium, a non-profit organization. VRML implementations are available from several different sources. Live Picture's format is actually an "extended subset" of VRML97, and Live Picture publishes the details of their extensions on the Web. QuickTimeVR is part of Apple's QuickTime technology, and is not an open standard-- it is controlled by Apple, and Apple is the sole provider of the technology.
Publish your panoramas in a format supported by Live Picture's Java applet, to make it easy for anybody to see your panoramas without downloading a special plug-in.
You may also want to publish your panoramas in the VRML97 format, so your users get the benefit of hardware acceleration (if they have the necessary 3D graphics hardware), or so that you can add sound, interaction, or other 'extra' elements to your panoramas.
Publishing in the QuickTimeVR format makes sense if your users already have QuickTime (it is widely available, and is a standard part of the Mac OS and the "full" versions of Netscape Navigator and Internet Explorer), you don't require a full 360° vertical field of view, and you want a robust viewer.
Once your panorama is created, converting between the various formats is fairly straightforward. You should consider making panoramas available in several different formats, and monitoring your visitors to see which is most popular.
Create your panoramas using whatever tools you find most affordable, effective or convenient, but be aware that the criteria for choosing panorama authoring tools are not necessarily the same criteria for choosing a panorama format for your web site.