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Orbit Legend File
OLG stands for Orbit Legend File. This is an extension file that can accompany any spatial storage format.
Structure
An orbit legend defines values for rendering parameters, stored in a text file.
For each rendering parameter a default value can be specified. In Orbit terms such a set of default values is called the “Basic Appearance” of a model. Depending on the spatial type of the model the rendering parameters may differ. Rendering parameters can be directly linked to the value of a specific attribute of each individual object.
A more advanced feature of the Orbit Legend system is defining a model-level classification on one attribute and then defining rendering parameters for each of the classification groups. That way individual objects will be rendered according to which classification group they belong to. Multiple classifications can be made within one model, as long as the rendering parameters defined for the classification group are not used in another classification. Classification is available for models of any spatial type.
Piechart rendering is a special rendering style rendering a pie in the middle of each object in the model. Pie slices can be determined by listing a number of attributes. That way the size of each slice is directly linked to the attribute value of each individual object.
Another approach is to create an object-level classification on one attribute. A color and label can be assigned to each classification group. That way the size of each Pie slice is defined by looking at the size of the classification group for the individual object. Using an object-level classification is only useful when an object has multiple attribute sets. Piechart rendering is available for models of any spatial type.
More information about the Orbit Legend tools : Dataset Legend Editor
Reasons to use
- offers extensive possibilities to customize data display, see Structure above.
- one file can be used for multiple datasets or multiple OLG-files can be used to display one dataset
- can be used to display all supported spatial resources
Create and Update
Generally a OLG file is stored on the same location and has the same name as the dataset itself. However, if no such “sibling” legend file is found, Orbit will automatically generate a default legend. Saving an unsaved legend (save button) will result in a legend file on the same location and with te same name as the dataset itself. It is not necessary to define the location and name to the file.
It is possible to store a legend file as a different name or on a different location. This option is common in the following cases :
- One dataset with more legend files - This is used for datasets which maintain a lot of information,which will be represented by several legends. Legend files with different names are legends that represent spatial information on a specific way such as classification, labels and/or Pie Charts.
- One legend file for more datasets - This is used for datasets who are similar to each other. This means having exactly the same model(s) and attributes, but the content is different.
Define the legend once and apply it for all other datasets.
The EOS Console will automatically recognize the legend file that is stored on the same location and with the same name as the dataset. It is not necessary to define it. When another name or location is used, the legend file must be defined. When another name or location is used, the legend file must be defined.
- One dataset with more legendfiles - One dataset can be set as many resources if each resource is linked to another legend.
- One legendfile for more datasets - Link one legend to more resources.