Complete chapter Vehicle structure (7.3.3)

[LudwigFriedmann]

Is your feature request related to a problem? Please describe. (TBD) Currently, the chapter and its subchapters are lacking text and illustrations. Even though the vehicle structure has slightly changed, https://github.com/asam-ev/OpenMATERIAL/blob/OpenMATERIAL_Legacy/model_structure/Vehicle_Structure.md and the Miro board can serve as sources of information.

Describe the solution you'd like Text and illustrations are added to the chapter.

Describe alternatives you've considered

Additional context

[LudwigFriedmann]

Open questions from the Miro Board:

• Do we need one parent object for the multiple parts?
  • Yes that makes sense, we should add a root node and call it "Root"
• Problem: Nodes cannot be named the same. So two vehicle parts cannot both contain a Grp_Exterior node
  • Proposal: Add vehicle_part_idx as suffix to all subnodes of a specific vehicle_part
• What about Caster and Camber angles?
  • Proposal: for definition of the z-Axis: Perpendicular to the x-axis, pointing vertically upwards not affected by caster and camber angles at neutral load conditions. Caster and Camber angles might be added to the asset file later.
• Where is the origin of the seats? (e.g. at the bottom, in the middle of the backrest, etc.)
  • For placing a passenger it makes sense to put the origin at the middle of the seat surface.
• What about the rear bench with 3 seats? Is this one seat or 3?
  • For placing a passenger it makes sense to have three different coordinate frames.
• Should we remove the eye point coordinates? They could be calculated from the seat position. To be further discussed.

[ipg-sig]

Where is the origin of the seats? (e.g. at the bottom, in the middle of the backrest, etc.) For placing a passenger it makes sense to put the origin at the middle of the seat surface. What about the rear bench with 3 seats? Is this one seat or 3? For placing a passenger it makes sense to have three different coordinate frames. Should we remove the eye point coordinates? They could be calculated from the seat position. To be further discussed.

Proposal: Origin of the seats: Middle of the seat cushion, so the helper bone for the seating can be used

For seated Humans (e.g. as drivers/passengers in a vehicle, we need a helper bone (seat) underneath hip bone We can then use the helper bone to position the 3D Model and we can also calculate the eye level with the length of the bones (with LOD3 of pedestrians, Hip to Head straight for Z, Head to Eye for X) if needed (could be done automatically by the exporter)

Bench with 3 sets: Can be one objects, but would need 3 seat positions, because you want to use all available seat positions.

Eyepoints: Could be calculated automatically from the seat position by export and would be indepenedant from the actual asset/ human upper body height which can differ vastly betweens passengers. This would allow us to calculate it specifically for each individual passenger or keep it simple by using the average sizes. So I would like to keep them in the definition, but they should be calculated by the exporter if needed.

[ipg-sig]

Addition for the seat positions: Count the seat index per level from first level right to left and front to rear, to the next level from right to left and front to rear. Note: A rear bench with 3 seats will be consideres as 3 seats, because 3 passengers could take a seat on it.

[LudwigFriedmann]

Discussion on details and coordinate frames takes place in #103. This PR can serve as a basis and should be merged quickly.

Proposal: Move any content that is not object-class specific to 7.2 General.

Proposal: Merge chapters 7.3.3.1 and 7.3.3.2 (remove headline "Model Creation"). Have object-class specific information either in 7.3.3.1 General or 7.3.3.3 Model Structure as introduction.