Figure 2-2: Nine Layers of Abstraction
We will discuss the nine layers one at a time. The first five layers, from the Real World to the Project World, deal with the abstraction of real world facts, and are not modeled in
software. The final four layers, from Points to Feature Collections, deal with mathematical and symbolic models of the world and are meant to be modeled in
software. Even so, this Essential Model of the final four layers assumes that they are real- world objects, and gives no specification, however abstract, for their implementation. The
final layer is the abstraction of reality specified in the language an information – the geometric and semantic description of a set of features or Feature Collection.
2.3. The Real World
By “The Real World” we mean the collection of all facts, whether they are known by mankind or not. Facts in the real world are understood in terms of their essence. For
example, a tree is something that belongs to the category of things that have “treeness.” Figure 2-3 is meant to represent the Real World. The cloud-like texture that occupies
most of the figure represents the wilderness of unknown facts that occupy the chaos of the universe. Only a few of these facts are recognized as familiar patterns, and some of
these are represented in the drawing.
The OpenGIS
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Abstract Specification Page
5 Volume 5: Topic 5: Features
Figure 2-3: The Real World
Figure 2-4 is an abstraction of Figure 2-3, using the Syntropy notation of [Cook94]. An object type is represented by a rectangle, with a name at the top of the rectangle.
Real World
Figure 2-4: The Real World Object Type
Figure 2-4 is an essential model in the sense of [Cook94], that is, it is intended to help understand a situation. The situation is the first step toward abstracting a part of the real
world into feature collections. Along the way, we will refine the concept of a Information Community for geospatial feature collections.
Human discourse does not take place at the Real World level. Instead, humans give names to things abstract them and communicate with each other using these names.
This naming process is exactly the method by which one interfaces to the next level of abstraction: the name method. The names are the proper and common nouns and
pronouns of our natural language, and they are the language of the Conceptual World.
2.4. The Conceptual World
