7.3.4 Environment structure

7.3.4.1 General

The environment consists of the terrain, buildings, objects, and traffic areas, for example roads. It also includes all stationary traffic items, such as traffic signals, signs or lights.

The environment’s 3D geometry is structured according to the node structure defined in Model structure. The structure begins with a root node, which is the parent of all other nodes. If applicable, the origin of the root node should match that of the corresponding OpenDRIVE map. Children of the root node are terrain, environment objects, and the road network. The latter is further detailed by its child nodes, the drivable area, sidewalks, roadmarks, road objects, and signals.

An example environment asset is provided in the examples folder.

Groups with a local transform are indicated in the structure by a (T). This is only an indicator in the documentation and must not be contained in the actual node name.

7.3.4.2 Naming convention

Every object has a unique name and represents a part of the environment. All included meshes are part of a group to indicate which kind of object type it represents. All meshes should be named meaningful.

If needed, the user is free to add more groups and new keywords, which are not part of the standard, for himself.

7.3.4.3 Model structure

7.3.4.3.1 Structure overview

7.3.4.3.2 Grp_Root

The environment consists of the terrain, buildings, objects, and traffic areas, for example roads. It also includes all stationary traffic items, such as traffic signals, signs or lights.

If applicable, the origin of the root should match the inertial coordinate frame of a corresponding OpenDRIVE map.

Table 109. Grp_Root
<Header>
Origin	Origin matching the inertial coordinate frame of an associated OpenDRIVE map (if available).
x-axis	Pointing to the right (east for maps with geographic reference).
y-axis	Pointing up (north for maps with geographic reference).
z-axis	Pointing out of the drawing plane (up for maps with geographic reference).

7.3.4.3.3 Grp_Terrain

The terrain is characterized by the environment’s ground structure, such as hills, mountains, or flat territory, meaning, the landscape in general. It does not include local elevations like vegetation, buildings, or other human-made structures.

Grp_Terrain is used as parent for all nodes defining the terrain of an environment. It shares the coordinate system with Grp_Root, see Table 109.

Figure 52. Grp_Terrain

7.3.4.3.4 Grp_Environment_Objects

Environment objects includes buildings, vegetation, and any other (stationary) objects in the environment. An environment object causes a local elevation or other addition to the terrain.

Grp_Environment_Objects is used as parent for all environment objects in an environment. It shares the coordinate system with Grp_Root, see Table 109.

Figure 53. Grp_Environment_Objects

7.3.4.3.5 Grp_Buildings

A building is a human-made structure and includes houses, towers, or skyscrapers.

Grp_Buildings is used as parent for all buildings of a Grp_Environment_Objects. It shares the coordinate system with Grp_Root, see Table 109.

Figure 54. Grp_Buildings

7.3.4.3.6 Grp_Vegetation

Vegetation includes all organic growth or plants that are part of the landscape. Vegetation can grow on the terrain or on human-made structures, for example between roads and buildings.

Grp_Vegetation is used as parent for all vegetation objects of a Grp_Environment_Objects. It shares the coordinate system with Grp_Root, see Table 109.

Figure 55. Grp_Vegetation

7.3.4.3.7 Grp_Road_Network

The road network is the entirety of a road. It includes the drivable area, sidewalks, and any other traffic objects, such as traffic signals, signs, or traffic lights.

Grp_Road_Network is used as parent for all nodes defining the road network of an environment. It shares the coordinate system with Grp_Root, see Table 109.

Figure 56. Grp_Road_Network

7.3.4.3.8 Grp_Drivable_Area

The drivable area is a traffic space that is dedicated to vehicles. It is the surface part of the road structure on which vehicles drive and includes lanes and parking areas. The drivable area for ASAM OpenMATERIAL 3D is comparable to the scope of the ASAM OpenDRIVE standard for on-road use cases.

Grp_Drivable_Area is used as parent for all nodes defining the drivable area of a road network. It shares the coordinate system with Grp_Root, see Table 109.

Figure 57. Grp_Drivable_Area

7.3.4.3.9 Grp_Sidewalks

A sidewalk is a traffic space that is dedicated to pedestrians and sometimes cyclists. Sidewalks are usually adjacent to the drivable area.

Grp_Sidewalks is used as parent for all nodes defining the sidewalks of a road network. It shares the coordinate system with Grp_Root, see Table 109.

Figure 58. Grp_Sidewalks

7.3.4.3.10 Grp_Road_Marks

Road marks include any markings on the road and traffic spaces.

Grp_Road_Marks is used as parent for all nodes defining the road marks of a road network. It shares the coordinate system with Grp_Root, see Table 109.

Figure 59. Grp_Road_Marks

7.3.4.3.11 Grp_Road_Objects

Road objects includes all other objects on or nearby the road, excluding signals.

Grp_Road_Objects is used as parent for all road objects of a road network. It shares the coordinate system with Grp_Root, see Table 109.

Figure 60. Grp_Road_Objects

7.3.4.3.12 Grp_Signals

A signal in the context of traffic is a visual sign used to control the flow of traffic. A traffic signal can be both a sign and a light. Signals describe the relevant area or volume of a traffic signal only. Posts and gantries are considered road objects.

Grp_Signals is used as parent for all signals of a road network. It shares the coordinate system with Grp_Root, see Table 109.

Figure 61. Grp_Signals

7.3.4.3.13 Grp_Sign_<signal_idx> (T)

Traffic signs belong to traffic signals. They are indexed using a <signal_index>. The <signal_index> can be taken over from ASAM OpenDRIVE or ASAM OSI. If no predefined indices exist, they can be generated by iterating over all signals from (0,…,n). The indices are used for both traffic signs and traffic lights. A traffic sign cannot have the same index as a traffic light in a single environment.

Figure 62. Grp_Sign_<signal_idx>

Table 110. Grp_Sign
<Header>
Origin	Geometric center of the signs face.
x-axis	Concentric and coaxial to the surface normal of the sign face.
y-axis	Completes the right-handed coordinate system.
z-axis	Perpendicular to the x-axis, pointing vertically upwards.

7.3.4.3.14 Grp_Traffic_Light_<signal_idx> (T)

Traffic lights belong to traffic signals. They show temporary changes in illumination. The <signal_index> can be taken over from ASAM OpenDRIVE or ASAM OSI. If no predefined indices exist, they can be generated by iterating over all signals from (0,…,n). The indices are used for both traffic signs and traffic lights. A traffic light cannot have the same index as a traffic sign in a single environment.

Figure 63. Grp_Traffic_Light_<signal_idx>

Table 111. Grp_Traffic_Light
<Header>
Origin	Geometric center of the traffic light signal area surface.
x-axis	Concentric and coaxial to the surface normal of the signal area surface.
y-axis	Completes the right-handed coordinate system.
z-axis	Perpendicular to the x-axis, pointing vertically upwards.