Introduction

      HotSauce was an innovative 3D fly-through interface for navigating information spaces [1]. The concept behind HotSauce was a simple one: “why just browse when you can fly?” It was developed, largely as a one-man effort, by Ramanathan V. Guha [2] whilst at Apple Research in the mid-1990s. HotSauce was a specific 3D spatialization of the Meta Content Framework (MCF) also developed by Guha. MCF was a way of describing and organizing the structure of an information space [3]. This is called metadata [4] and is separate from the actual content. For example, a library catalogue is vital metadata that enables books to be found on the shelves.

      HotSauce worked as a plugin to an existing browser so that when a hyperlink to a MCF-enabled website was selected the user was dropped into a first-person perspective view of the Web. It was a videogame view with Web pages floating as brightly colored blocks in an infinite black space, something like the view from a starship cockpit navigating through some strange asteroid field. It was easy to fly into and around the space, using the mouse to guide the direction of flight and holding down buttons to go forwards and backwards. A page could be accessed by simply double-clicking on the relevant block.

      Individual web pages were represented by rectangular blocks, labeled with the page title, while broader 'topics' were indicated by the round-cornered rectangles and these provided an organizing structure for the information space. Different hierarchical levels of the information space were denoted by different colors of the floating blocks as well as their spatial depth in the 3D display. So, in the example screen dump, the green block represents the top-level, indicating that this is a spatialization of the website of Sailmaker Software. The red blocks are the second level and so on.

An example of the HotSauce interface, showing the Sailmaker Software website.

Making the Web Flyable

      In a recent email interview with Guha, Map of the Month asked him about the development of HotSauce. Guha's background is in artificial intelligence with a PhD from Stanford and years of research in symbolic knowledge representation. This was useful in developing the MCF information structure underlying the HotSauce visualization. A key aim was to keep MCF conceptually and technically simple, so it would be easy for non-specialists to apply to their own websites, thereby encouraging rapid adoption. The HotSauce interface began, according to Guha, as an experiment in ways to layout the large, hierarchical MCF structures in a 3D space. He chose 3D visualization because “when you take a large structure like that and view it via a 'flat' interface like html, it is hard to get a visceral feel for the structure.” Guha then found, “I needed a way to navigate this space. Hopping around from point to point was just not enough and so the next step was to fly through this space.”

      Guha says that one of HotSauce's major strengths was that it was “fun to use.” In developing the fly-through interface the key challenges were creating a non-linear layout of the hierarchy in 3D space, as well as creating display algorithms capable of drawing the text fast enough onto the screen to give the impression of smooth flight.

      Although smoothly zooming through HotSauce space is quite fun, it can be surprisingly hard to find pages and fly towards them. And once you get immersed in the space and surrounded by blocks it is easy to become disorientated. “The major weakness was that it had no terrain. ... People are not used to flying around anything,” acknowledges Guha.

      Despite the practical difficulties in actually using HotSauce for browsing the Web, it was still an important development, as Steven Johnson notes in his book Interface Culture:

      “But a day or two with HotSauce was enough to catch a glimpse of what a genuinely spatial systems might feel like. At a few, enthralling moments, I found myself groping around for a familiar document and thinking: It's back there somewhere, up and to the left a little, about two or three planets deep. For a second or two I was thinking in purely spatial terms, zooming in and out of my own private dataspace. For those few moments, there was a hint of liberation in the air, the promise of things to come.” (page 80) [5]

Flying Onwards

      Since leaving Apple Research in 1997, Guha has been active in developing the Resource Description Framework (RDF) and Smart Browsing technology as a principle engineer at Netscape Communications. RDF is major metadata initiative, and develops many of the key ideas in MCF, and potentially will greatly improve the use of the Web with new standards for describing information resources, providing advanced cataloguing and searching tools [6]. In May 1999 Guha co-founded Epinions, Inc.

      Guha still believes that information visualization is an important avenue for managing and searching the Web. However, he comments, tellingly, “but I think we still haven't found the right simple visual metaphors. It amazes me that folks still plod through long lists.” Map of the Month therefore asked what his 'dream' map of the Web would be. In his answer he pointed to the new visual search directory recently launched by Antarcti.ca [7], on which he acts as a technical advisor:

      “A 3D immersive environment where I could move around an Antarcti.ca like space, moving things around, interacting with others in that space. And I should be able to do this wherever I am!”