GSModel Geospecific 3D Model T2DModel Tiled 2D Model MModel Moving 3D Model

67 © 2016 Open Geospatial Consortium http:opengis.netspecCDB1.0cor ecultural-representation The cultural features of a CDB data store SHALL be represented using one of the following types of modeled representations: a GTModel: 3D modeled geotypical representation of a point-feature that is anchored to the ground. b GSModel: 3D modeled geospecific representation of a point-, lineal- or polygon-feature that is anchored to the ground. c T2DModel: 2D modeled geospecific or geotypical representations of point-, lineal and polygon features that are anchored to the ground. d MModel: 3D modeled representations of point-features that are not anchored to the ground. The modeled representation of a feature primarily consists of its geometry and textures, and encompasses its exterior and interior. In this Standard, the following terms and expressions are used: ● The term Model refers to all of the modeled representations of a cultural feature. ● The term Model-LOD refers to a specific level of detail of a Model. ● The term 2DModel refers to the modeled representations of a 2D feature, i.e., a feature that has no significant height with respect to the underlying terrain. ● The term 2DModel-LOD refers to a specific level of detail of a 2DModel. ● The term 3DModel refers to the modeled representation of a 3D feature that can be readily distinguished from the underlying terrain. In the case where the 3DModel is unique, it is referred to as a GSModel. In the case where the 3DModel is instanced, it is referred to as a GTModel. A 3DModel that is capable of movement is called a MModel. In the case where a MModel is positioned by the modeler, it is called a statically- positioned MModel. ● The term 3DModel-LOD refers to a specific level of detail of a 3DModel. 3.3.1 GTModel Geotypical 3D Model A feature is said to have a 3D geotypical modeled representation if it is associated with a 3D Model that is typical of the feature’s shape, size, textures, materials, and attributes. The use of geotypical models is appropriate if the modeler does not wish to fully replicate all of the unique characteristics e.g., shape, size, texture of a feature, as they are in the real-world. When a feature is represented by a geotypical model, the modeler is in effect stating that two or more features of the same type i.e., samefeature code have the same modeled representation.

3.3.2 GSModel Geospecific 3D Model

A feature is said to have a 3D geospecific modeled representation if it is associated with a 3D model that is unique in shape, size, texture, materials, and attributes. The use of geospecific 68 © 2016 Open Geospatial Consortium models is appropriate if the modeler wishes to fully replicate all of the unique characteristics e.g., shape, size, texture of a feature, as they are in the real-world. As a result, a geospecific model usually corresponds to a unique real-world recognizable cultural feature. Real-world features such as the Eiffel Tower, the Pentagon, or the CN Tower, to name a few, are usually modeled as geospecific.

3.3.3 T2DModel Tiled 2D Model

A feature is said to have a 2D modeled representation if it is associated with a modeled representation that has no significant height with respect to the underlying terrain and generally conforms to the terrain profile. It is convenient to think of the 2D Models as a complement and as an extension to the Primary Elevation and VSTI Imagery datasets. 2D Models provide the means to represent 2D surface features that are conformed to the underlying terrain: a Modeled representation of geotypical and geospecific 2D lineal-features such as roads, runways and taxiways, stripes. b Modeled representation of geotypical and geospecific 2D polygon-features such as aprons, surface markings, contaminants, land usage campgrounds, farms, etc.. 2D Models can also be used to model geotypical terrain textures as a mesh of 2D textured polygons overlaying the terrain. This modeling technique replicates approaches used in early Image Generators which had limited ability to page-in geospecific terrain textures.

3.3.4 MModel Moving 3D Model

A moving model is typically characterized as such if it can move on its own or be moved. More specifically within the context of this standard, the model is not required to be attached to a cultural point feature. During the course of a multi-player simulation 21 , each client-device is typically solicited to provide a modeled representation of each of the players. The activation of such players requires that the client-device access the appropriate modeled representation for each of players. There are a large number of military simulations where the player types are characterized by their DIS code. To this end, the CDB data store provides a moving model library whose structure provides a convenient categorization of models by their DIS code.

3.3.5 Use of GSModels and GTModels