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geoscene3d:concepts:object_order

Object Order

The 3D objects are not rendered as layers on top of each other as in an ordinary 2D GIS applications. In this respect objects are considered as a group of objects or a theme rather than a layer. However, the order of objects as they appear in the Object Manager is significant if some objects are transparent.

Objects are rendered in the order they appear in the Object Manager from bottom up. This resembles the way layers are rendered in 2D GIS applications. In 2D this rendering order ensures that top layers are shown above lower layers. However, in 3D objects are not always viewed from a top down position but may be viewed from any direction including bottom up.

The 3D engine (OpenGL) checks for the distance to the camera and will not render farther opaque objects on top of nearer objects even if they are renderer later than the nearer object. However, in the object manager, partly transparent objects MUST be situated above the objects that should be visible through the transparent objects. Hence, if Object 1 is transparent relative to object 2 (object 2 visible through object 1, and object 1 closest to the camera), object 1 must bust be situated below object 2 in the object manager.

Example: If a terrain surface should be transparent allowing wells below the surface to be visible through the terrain the terrain must be rendered later than the wells. This means that the terrain surface must be situated above the wells in the Object Manager, see below image.

In general the terrain model should be positioned high in the object manager and subsurface layers and subsurface objects placed below the terrain model. This will give the right transparency effect when viewing the scene from a position above the terrain.

Permalink geoscene3d/concepts/object_order.txt · Last modified: 2020/02/17 18:15 by rebecca130301_gmail.com