geGIS factsheet

A quad tree is a datastructure that allows for fast indexing and retrieval of geographic information.

Definition: The expression of a two dimensional object such as a digital image, as a tree structure of quadrants which are formed by recursively subdividing each non-homogeneous quadrant until all quadrants are homogeneous with respect to a selected property, or until a predetermined cut-off depth is reached.

For each layer it is possible to determine to what other layers snapping is allowed. Snapping always happens to the points of other geometries.

Style definitions are based on CSS styles. For each layer it is possible to predefine one or more styles, with attached filters. These styles also support transparency.

The standard zooming controls zoom in or out on click. Zooming to a rectangle or a maximum map extent is also supported.

The 'Fit' functionality is basically a 'zoom extent'. It is possible to zoom to selected objects on the map.

Panning can be done by either buttons in the toolbar, or by dragging the mouse on the map.

Selection of object on the map. (can be used for the 'fit' control, or for export of information about the selected objects)

Determining distances by dragging on the map. Supports snapping.

Creation of new geometries, editing or deleting of existing geometries.

One way of filtering is by attributes. Supported operators are <, <=, =, >=, >, LIKE, AND, OR.

Geographic filtering can be done by comparing the geometry of an object to the geometry of objects in any layer. Supported operators are: INSIDE, CONTAINS, INTERSECTS.

Currently each layer can show one of it's attributes as a label. Labels look different for each geometry type.

Tiling is the splitting of large datafiles into a grid of smaller files, so it's not necessary to search through the large file to reach the relevant information. Multi-level tiling is the repeating of this idea for more then one scale-level. This to increase efficiency. Subtiling on the other hand is the further splitting of some tiles, as a quadtree does.

This is supported for both vector and raster layers, and uses caching for performance.

Through the use of CSS in an SVG tree, it is possible to make anything transparent. This also inclues the objects in layers, whether they are raster or vector based.

Possibility of exporting all object in a layer. It is recommended to restrict this through configuration. (XML, CSV)

Support for the export of currently selected objects. (XML, CSV)

Export the current view to an image. (GIF, JPEG, PNG)

Export the current selection into a report. These reports need predefined templates. (PDF)

Export the current view for printing. Makes use of predefined templates for printing. (PDF)

Support for the usage of the online CRAB webservice.

Searching objects by attributes and displaying them in a table view.

Visible objects on the map can also be displayed in a table view (for each layer), that shows their attributes. Filtering and sorting is supported.

Overview map whitch shows the current view on the main map.

All layers are shown in a tree structure, with the possibility to make them visible/invisible, or to activate/deactivate labels, ...