3D layers can be classified using polygons (generally from a feature layer) that contain attribute data relevant to the mesh layer. These classification polygons enable you to visually distinguish different areas of the 3D layer, access the attribute data of the classification features and perform spatial and attribute queries on the feature layer that is classifying the 3D layer. The classification can be displayed either by colorizing or by displaying a 3D polygon around the intersecting layers and objects. The classification is dynamic, reflecting any changes to the polygon features, and requires no pre-processing. This means that multiple feature layers can classify a single 3D layer and multiple 3D layers can be classified by any particular classification feature layer.
Skyline continues to provide legacy support for classification layers created in older versions of TerraExplorer Pro that have been pre-processed with specific 3D layers.
To use a feature layer as a classification layer:
- Load the required feature layer.
- In the layer's property sheet, set the Altitude Method to Relative to Terrain or Absolute, and set the Classification Mode. More about: Volume classification >
- Set the appearance, e.g., fill color, altitude, or visibility, of your classification polygons. More about: Setting and editing feature layer properties >
To create a new classification layer:
- On the 3D Layer tab, in the Volume Classification group, click Create Layer. The Create Classification Layer dialog box is displayed.
- Enter the following information:
- Layer Name - Name of the classification layer.
- Altitude Mode - When creating a classification layer for buildings, generally the layer’s Altitude Method should be set to Relative to Terrain and Extrude Up / Front and Down / Back should be set to fixed values that correspond to the height of the tallest building. When creating a classification layer for other building elements, e.g., floors, windows, and doors, the layer’s Altitude Method should generally be set to Absolute and Extrude Up / Front and Down / Back should be set to By Attribute. Each individual polygon’s altitude and extrude values should then be set according to the element being classified.
- Extrude Up / Front and Extrude Down / Back - Length to extrude the layer’s polygons upwards/frontwards or downwards/backwards in the direction of each polygon’s normal. Select either: Fixed Value – Fixed value in meters for all layer polygons or By Attribute – The extrusion value for each of the layer’s polygons is taken from the value set for the polygon’s “Front” attribute.
- Attribute Name - Add as many attributes as required. For each attribute, type a name and enter the attribute type. If you want to colorize the layer based on one of the attribute's values, switch Color Classification on for that attribute.
- Click Create.
- In the Project Tree, select the created classification layer, and set additional properties if required. In the Volume Classification section of the property sheet, set the Classification Mode for the classification polygons to either colorize or display a 3D polygon around the intersecting areas of the mesh layer. More about: Polygon property sheet parameters >
- Add the required classification polygons. More about: Adding a feature to a layer >
If Extrude Up / Front and Down / Back were set to “By Attribute”, enter values for the front and back attributes added to each polygon.
The appearance, e.g., fill color or altitude, of the classification polygons can be based on layer attribute fields. More about: Basing native feature layer properties on attribute fields >