About setting the role of a 3D layer in ArcScene
Layers can play a variety of roles within the 3D view. They can float independently of other layers, drape on top of a separate 3D surface, or provide surface heights for other layers to drape on.
ArcScene does not distinguish the layer categories in the table of contents as ArcGlobe does. Similarly, you will not see the Add Data Wizard as you would in ArcGlobe; however, layers can still be configured to act in a similar manner for a particular category as they would in ArcGlobe. For example, a point layer can reference a raster surface for its base height information, which is the same result as creating a draped layer in ArcGlobe.
Elevation layers
ArcScene does not have the notion of an elevation-only layer in the table of contents. Instead, each draped layer will specify an elevation data source independently of other layers.
Elevation source layers are used to provide base heights for other layers. Example sources of elevation data include single-band DEM rasters, TINs, and terrain datasets. ArcScene cannot directly consume terrain datasets as an elevation source, so you will need to export your area of interest to either a raster or a TIN to consume the data. You can use either the Terrain To TIN tool or Terrain To Raster tool to complete the conversion.
Draped layers
Draped layers use other layers as elevation sources. Drape a layer to show it on a 3D surface. For example, you might drape an aerial photo and its associated features on a mountaintop.
Floating layers
Floating layers are used to show rasters or features that are not placed on the elevation surface. Examples of floating layers include underground or aboveground utilities, aircraft, and clouds.
In ArcScene, a floating layer is drawn independently of any surface and may get height information from a constant value or expression, or use z-values stored inside the feature layer geometry. Floating layers that do not have z-values in their geometry are initially shown with zero height values.
Rasters and 2D features are added into ArcScene as floating layers by default.
The images here depict base height options from the Layer Properties dialog box in ArcScene. The illustration changes to reflect the selections made on the Base Heights tab to show how the layer will be displayed in the 3D view.