Geographic Objects

G of GIS can be interpreted as Geographic Object or Spatial Object or Spatial feature or Geographic Individuals. At the planet scale, our world is only one object with the defined boundary. At the global scale, you can view our planet as water and land mass. They have their owned defined boundaries. In our planet, there is more water mass than land mass. It is interesting why our planet is called Earth rather than Water. Anyway, at the more refined scale, electric poles, rivers, roads, tramlines, water pipes, fire hydrants, lakes, vineyards, agricultural land and the forest patches are examples of geographic objects. Most of the tangible geographic objects have the defined acceptable boundary and properties such as name, types and status etc. These are called discrete geographic objects. These are also called discrete objects. For example, lake Geneva has a defined boundary. Its name (property) is called Geneva lake. After that boundary, it is not known as Geneva lake. It is one of the most famous (status) urban lakes in the world. Therefore, Geneva lake is a discrete geographic object.

• The geographic boundaries are defined non thematically or thematically.
• The national boundaries are defined as the nationality as a theme.
• Land use and land cover boundaries are defined thematically.

These geographic objects have the phenomena too. It is difficult to delineate the boundary of these phenomena. Most phenomena are intangible or perceptible by sense such as temperature. Some phenomena are tangible such as distribution of vegetation at ecotone. Ecotone is the fuzzy boundary between two ecological communities. Temperature, rainfall, elevations and ecotones are good example of phenomenon. At the global scale, we cannot draw the temperature temperature boundary of our earth. At the more refined scale, we cannot still draw the temperature boundary of Geneva lake. Because, the boundary of the phenomenon does not truly exist. It exists arbitrarily as the fuzzy boundaries. The phenomena are continuous in nature. Therefore, these phenomena are illustrated with arbitrarily defined boundary which are normally fuzzy. We will learn how to draw the fuzzy boundaries for phenomena.

These phenomena are illustrated as continuous surfaces using grid cells. Each grid cell has a real value of phenomenon (e.g. continuous temperature) based on field measurements and interpolated values.

More detail on sampling and interpolation to generate the continuous phenomenon of geographic objects will be discussed in a dedicated lesson. Moreover, we will learn how to represent continuous phenomenon surfaces into arbitrarily defined fuzzy boundaries as discrete objects in the future units.