649week04 → Pictures of Prominent Tools
I mentioned Spotfire and Inxight, InfoViz tools that have enjoyed commercial success over many years and that were the product of an era when only those with access to Silicon Graphics workstations. InfoViz was exclusively the province of those who could forge partnerships between software engineers and cognitive psychologists.
http://www.inxightfedsys.com/pdfs/VizServer_Finalweb.pdf shows the three main information representations associated with Inxight, the hyperbolic browser, shown as StarTree in the brochure, Table Lens, and the perspective wall, shown as TimeWall in the brochure.
These tools share the common theme of focus and context. The hyperbolic tree browser is a technique for viewing hierarchical relationships in a very compact way. The original paper on this topic (Lamping and Rao 1996) claims that this representation can show ten times as many nodes in a given area as can what they call a conventional tree browser. This technique implements a fisheye view as the means of providing focus plus context. The fisheye view concept should be familiar to you from your foundational courses and was popularized by Furnas (1986). The center of the fisheye provides a large area around the item of interest, while the periphery compactly summarizes vastly more relationships.
hyperbolic tree browser
You might ask what makes this hyperbolic? It is a model of hyperbolic geometry. A famous model of hyperbolic geometry by M.C. Escher reveals the key property that the distance from a point on a circle in hyperbolic space grows exponentially with the radius of the circle. The way that Circle Limit IV reveals this is that you can count the number of angels or demons and see how fast they increase from the center. This exponential growth property makes the hyperbolic plane attractive for InfoViz in that it directly addresses the problem of information overload.
Escher, Circle Limit IV
The Table Lens is another focus plus context technique, in this case for displaying tabular data. Notice that in the following illustration you can tell many properties of the data at a glance and that the evident properties help you identify rows of the table to zoom in on for more detail.
table lens
The Perspective Wall is another fisheye view technique. Notice that you can see an overview of the two oblique walls and detail on the facing wall. George Robertson, one of key people in the development of InfoViz, studied how people navigate this structure extensively. I believe that I heard one of his colleagues say that this was among the formalisms of Robertson’s invention selected for inclusion in Microsoft Vista, more than a decade after its introduction. Unfortunately, Robertson’s formalisms were apparently discarded as Microsoft Vista was delayed.
perspective wall
Tags: fisheye-views, focus+context
Among all visualizations here and in the readings, it seems that color is the most effective and popular retinal variable to distinguish different objects. It is primarily because color is the most salient visual stimulant for most users, and marking data by color provide an intuitive way for people to discover patterns and correlations. Value and size are also commonly used variables, while orientation and texture are not used in the examples from this weeks’ readings. In Ahlberg 1996, except the hues, brightness is used as another variable in Spotfire.
I love focus + context viz, and the concept is executed well in the examples here. Maybe it’s the key to info viz without information loss - you can get the big picture without having to actually delete any information - you simply have to interact to actually view the smallest details.
Color is effective, but it can also overwhelm. Color works well in the hyperbolic tree because it enhances patterns. Looking at the perspective wall, I can’t figure out what the colors might represent without finding a further description or interacting with the tool. So is color always helpful for enhancing learning? Does it always reduce the cognitive load? I’m not sure…
Information visualized in a fisheye view technique can be especially effective since the audience can grasp the details of entire context. As the users are faced with the reality of searching and retrieving simultaneously with multiple sources that differe in content and medium, digital library will require creative and efficient ways of presenting the rich data to the users. One idea of this is to maybe to incorporate a fisheye technique to allow the users to view the details of the context at large.
Now that I think about it, using different color on the interaction map turned out to be very effective. For our interaction map (for SI622), we had differentiated each task that a user would be doing on the website by red, green, and blue, and it was really effective in lessening the amount of effort that a reader needs to understand the map.