A dataset is defined by a type class definition to define the structure of the data stored in the datasets and a dataset class definition to define the metadata structure of the datasets containing the data. GeolinQ supports three types of datasets:
- Administrative datasets to access administrative data
- Feature dataset to access feature data
- Point dataset to access point data
The import and export formats available are dependent on the dataset type. A dataset is the interface to data stored in GeolinQ or linked by GeolinQ. A dataset is connected to datasource by a driver. GeolinQ supports two types of drivers for entity and feature datasets:
- Catalog driver for datasets with a database table as source
- View driver for datasets with a GeolinQ dataset as source
For point datasets only the catalog driver is supported. For feature datasets and point datasets the dataset footprint or a thematic representation based on a colour scale (for point datasets) or style (for feature dataset) can be rendered on a map. Feature datasets and entity datasets can also be shown in a tabular view.
GeolinQ is designed to contain considerable amounts of datasets. Datasets are queried by the datasource, the dataset class definition or their metadata attributes, the type class. Spatial queries are supported as well.
The Datasets tab gives access to the datasets query window. The left pane shows the query dialog to enter the query and the results list with the datasets selected by the query. The right pane shows the map. The footprints (hulls) of the selected datasets are shown on the map.
The query dialog allows querying on datasource, dataset class (metadata schema) and type class. When a dataset class is selected one or more attributes of the selected dataset class can be added to the query by clicking Add attribute.
A spatial constraint can be added to the query. Press Add spatial constraint button on map toolbaar and drag a box on the map.
Press Search to execute query. The selected datasets matching the query conditions are shown in the results list. The footprints of all selected datasets are shown on the map.
When querying on point type class and all selected point datasets have a common attribute for visualisation, a picklist to select a point attribute, a picklist to select a color scale and buttons to update, delete and add color scales are added to the map toolbar.
Select an attribute from the attribute picklist and a color scale from the color scale picklist to render point datasets in a different color scale. If required a new color scale can be created or existing color scales can be updated.
When querying on feature type class, a picklist to select a style and buttons to update, delete and add styles are added to the map toolbar.
Select a style from the style picklist to render the feature datasets in a different style. If required a new style can be created or existing styles can be updated.
When clicking on a single dataset in the results list, tthe map automatically zooms to the dataset and the footprint of dataset is shown on the map in the Preview tab. The Properties tab gives the attribute values of the previewed dataset.