The Dataset Structure

In Orbit, all 'datasets' consist of at least one model. Each model contains objects or Spatial Information Objects (SIO) , and is defined by a Spatial Component and an Attribute Component.

• The Spatial Component defines the type of geometry (point,line or area) of the objects in the model, and the number of coördinates (2D or 3D) by which each vertex is defined. A vertex can be considered as a special kind of point which describes the geometric shape.
  
  
• The Attribute Component holds the descriptive data in tabular form. This consists out of one or more Attribute Sets (or Attribute Tables) which is the equivalent of a table definition: a range of attributes (or fields) with their datatype definition. For each Attribute Set, the Attribute Component can hold one or more data rows. Each row contains a value for each field in the Attribute Set.

The properties of the Dataset Structures differences in various file formats:

• A Shapefile always consists of just one model (and therefore contains objects of only one geometry), and contains only one Attribute Table.
  
  
• A native OVF-file can consist of several models and contains therefore more possibilities: One can create a dataset with spatial objects that belong with each other but that have a different geometry (for example, roadmarks consists of lines, areas and points). It reduces the number of files which simplifies its management. It reduces the number of datasets in the datasetlist adding clarity to the global view. The OVF-format can contain more Attribute Sets (or Tables) and different values for one attribute.