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Data Structures
Datasets
Orbit Technology generalizes all types of spatial resources to Datasets. A Dataset is thus a defined and ordered bundle of spatial data.
Depending on the type of spatial resource, the internal organization of a Dataset is determined by the Resource Driver. Different storage formats present higher or lower levels of definition, structure etc.
What does a Dataset contain ?
- Properties
Every dataset contains a range of properties for which Orbit GIS presents the Dataset Properties editor. - Models and Objects
Every dataset contains one or more Models. Models contain Spatial Information Objects.
Models
Orbit Technology obliges spatial data to be structured exactly as defined. The way to organize that is to define Models, and to link all spatial data structured accordingly to that model.
What does a Model contain ?
- Model Definition
This is the definition of how a spatial object should be structured. - Spatial Information Objects
This is a list of spatial objects that comply to the Model definition
What is a Model Definition ?
The Model definition defines the structure for a group of objects.
| Element | Comment |
|---|---|
| Spatial Component Specifications | Defines the nature of the spatial part of a Spatial Information Object : Point, Line, Area or Image |
| Attribute Component Specifications | The structures of the attributes : one or more tables containing one or more fields with exact type definition. |
| Reference Component Specifications | Definitions about references to other objects, if any : nature of relationship, list of referred datasets, etc. |
| Layout Component Specifications | Definition of used Layout Styles, if any. |
According to the storage format, the model definition is either extracted from the stored data, or dynamically generated by the Resource Driver.
What about Legends ?
Technically spoken, a legend is not a part of the data structure, but merely a description on how the data must be graphically represented. A legend is therefore defined at the level of a Model, since the Model contains the definition for the objects to be drawn.
Practically, since models build up a dataset, a legend for each model is put together are stored in a single legend file containing the legend for all models in a dataset.
Legends may also include definitions for symbols, labels or charts.