Why Are Topic Maps not Maps?

Recently I was experimenting with map software. No, not with Topic Maps software, but software for cartographic maps, such as GRASS or MapServer.

While the choice for the term Topic Maps is quite natural to me, it was (and still is) not yet clear to me how far the analogy with maps actually goes. There is something about cartographic maps which all graphical representations of topic maps I so far do not seem to have:

  • A metric, i.e. a concept of distance.
  • An elevation, or more generally, a spatially varying property for the 3rd dimension.

I personally miss these concepts from Topic Maps and specifically from graphical representations of maps. Conventional visualizations are all for graphs, and the only issue there seems to be which details of maps to show and which not:

  • in which detail should associations be shown?
  • should typing information be included?
  • should only a focus of the map be visible?

This is all well and good but there must be a reason that this eye candy often remains exactly this: eye candy. And as such these representations are difficult to navigate with. Too many dimensions.

Let us have another look at conventional maps.

Distance

Any distance between two points on the map corresponds to the geographical distance the real locations have, depending to a more or less high degree on the projection function which is used to connect every location on the 3D sphere (Earth, for instance) with a point onto a 2D plane.

http://kill.devc.at/system/files/world-small.jpg

One obvious choice of distance for Topic Maps is to use the distance indicated by the number of associations between two topics, but that gives us the same topology as graphs.

There are many more problems with this, one being that all associations are counted to have equal distance. Which does not really reflect the semantic distance between two topics.

Another more linguistic pathway would be to find the semantic distance between the concepts the topics represent. But that is at best a research field and would imply that there is a lookup database for coordinates. And these coordinates must be absolute, so that it is possible to relate every point to every other point. This does not seem to exist yet and if it would, it would somehow question the claim of the TM community to bring mapping order into the concept chaos.

There are actually a number of clever ideas how to make graph-like representations more meaningful, among them being cartograms and TreeMaps. The following map shows the death toll of avalanches between 1975 and 2000:

http://kill.devc.at/system/files/cartogram-small.jpg

(The Westbank in Palestine seems like a safe place to me.)

Accordingly, the space a topic occupies is somehow proportional to ... well, any number we generate for that topic. That can be the number of associations it is involved in, the number of occurrences (or even names), or any combination thereof.

It can also, and that is much more meaningful, be derived from the documents the occurrences point to. Sure, it would mean that these documents have to be analyzed for the relevance of their content, essenced and statistically processed, but that is nowadays quite trivial.

A graphical map representation would then look more like the cartogram above. Many researchers have been here before, such as for instance BibTechMon.

Elevation

But what about a third dimension? Something like this:

http://kill.devc.at/system/files/contour-small.jpg

What should it actually mean in terms of the topic map content? What are high mountains, steep slopes and long ranges?

More about that later.

AsTMa

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Posted In

maps off topic

I'm not sure about topic maps, but maps of topics I know as well. eg:

Non geopgraphic mapping: http://www.number27.org/work/maps/traveltime/index.html

Mapping of feelings: http://www.wefeelfine.org

Star mapping of earths topics: http://universe.daylife.com/

and my favourite off topic map: mapping worlds states over the last 50 years (in 3 or more dimensions): http://www.gapminder.org

Marcus Meisel (not verified) | Fri, 12/07/2007 - 02:05

Re: maps off topic

Yeah, I'm completely hooked on this map (not topic maps) thing. Very fascinating.

Still, I am looking for ideas how much of all this map technology can be leveraged into TMs.

rho | Tue, 12/11/2007 - 11:12

Visualization

FWIW, here's a site on visualizing complexity.

Maps are about finding stuff, and especially stuff at the bottom of Maslow's hierachy, like food, drink, security, safety. (Most of the work at Visual Complexity seems to be about self-actualization, the top of Maslow's heirarchy, and actualization in the form of completed project deliverables that inspire hours of contemplation.)

So, in the sense of being about finding stuff -- like food, drink, security, safety -- topic maps are definitely maps.

Now, there is no cartography of desire (that I know of) which could explain why topic maps (so far) lack metrics and elevation.

Sam Hunting (not verified) | Wed, 02/27/2008 - 18:40

Re: Visualization

FWIW, here's a site on visualizing complexity.

Yes, I found it on your blog today. The range of ways to represent things is staggering. I have been intrigued also by this eco language.

Maps are about finding stuff, and especially stuff at the bottom of Maslow's hierachy, like food, drink, security, safety.

Hmmm. But maps also allow to aggregate things, geographically or semantically. Certainly something which may help with problem solving.

So, in the sense of being about finding stuff -- like food, drink, security, safety -- topic maps are definitely maps. Now, there is no cartography of desire (that I know of) which could explain why topic maps (so far) lack metrics and elevation.

I suspect one part of the solution to be in the aggregation concept. It implies a containment relationship and that could induce a location concept.

rho | Wed, 02/27/2008 - 22:02