MPAI-OSD V1.5 Data Types – Location

1     Definition	2     Functional Requirements	3     Syntax
4     Semantics	5    Conformance Testing	6     Performance Assessment

1      Definition

Location is a Data Type representing a portion of Space-Time defined as a wrapped region composed of connected elementary space portions.

A Location SHALL define:

• a wrapped region (boundary enclosing space)
• a set of elementary space portions composing the region
• structural relationships (connectivity) between the portions

a hierarchical composition down to non-subdivided Basic Locations

2      Functional Requirements

The Location Data Type SHALL support the following formats:

• Box Set (Parallelepiped-based, also called Simple Location)
• Tetrahedral Set (e.g. Delaunay-based)
• Voxel Grid

Each format SHALL conform to:

• Functional Requirements
• Format Specification
• Semantic Definitions

Common Functional Requirements

All Location formats:

• SHALL represent a portion of Space-Time
• SHALL define:
  • a closed (wrapped) region
  • a set of elementary space portions
• SHALL include:
  • explicit volumetric elements
  • connectivity between elements
• SHALL ensure:
  • continuity of the region
• SHALL support:
  • reconstruction of the interior region
• MAY include:
  • multi-resolution representations
• SHALL be:
  • machine-parsable
  • self-contained

Basic Location Constraints

A Basic Location:

• SHALL be:
  • continuous
  • not further subdivided
• SHALL be:
  • representable as a connected set of elementary space portions

Location Object Constraints

A Location Object:

• SHALL:
  • contain Locations and/or Basic Locations
• SHALL represent:
  • hierarchical containment (topological inclusion)

3      Syntax

https://schemas.mpai.community/OSD/V1.5/data/Location.json

4      Semantics

Label	Description
Header	Location Header – Standard “OSD-LOC-Vx.y”
MInstanceID	Identifier of a virtual space including the location.
UEnvironmentID	Identifier of a real space including the location.
LocationID	Identifier of the Location instance.
LocationType	Type of Location (BasicLocation or LocationObject).
LocationData	Data structure encoding the Location according to its format.
Boundary	The wrapper enclosing the portion of Space-Time.
Connectivity	Structural relationships between elementary space portions.
SpaceTime	Space-Time attributes associated with the Location.
Hierarchy	Inclusion relationship between Locations and sub-Locations.
DataXMData	Information about this Location instance.
DescrMetadata	Descriptive Metadata.
Box Set	Section grouping semantics specific to Box Set format.
Boxes	Array of parallelepipeds defining elementary space portions.
Center	Reference point of a box.
Size	Dimensions of the box along three axes.
Orientation	Orientation of the box in space.
Connectivity	Defined by adjacency or overlap of boxes.
Boundary	Outer envelope of the union of all boxes.
Continuity	Property indicating that boxes form a connected region.
Tetrahedral Set	Section grouping semantics specific to tetrahedral format.
Vertices	Array of 3D coordinates defining points in space.
Tetrahedra	Quadruplets of vertex indices defining tetrahedra.
Connectivity	Defined by shared faces between tetrahedra.
Boundary	Faces not shared by two tetrahedra define the outer boundary.
Continuity	Property indicating that tetrahedra form a connected region.
Voxel Grid	Section grouping semantics specific to voxel format.
GridOrigin	Reference origin of the voxel grid.
GridSpacing	Distance between voxels along each axis.
Voxels	Set of occupied voxel indices.
Connectivity	Defined by adjacency of voxels.
Boundary	Interface between occupied and non-occupied voxels.
Resolution	Spatial resolution of the grid.
Continuity	Property indicating that voxels form a connected region.
Hierarchy Semantics
Locations	Set of Locations contained in a Location.
BasicLocations	Set of Basic Locations contained in a Location.
Containment	Topological inclusion relationship between regions.
DataXMData	Information about this Visual Geometry instance.
DescrMetadata	Descriptive Metadata.

5     Conformance Testing

A Location instance conforms with Location (OSD-LOC) if:

• The data validates against the Location JSON Schema
• All fields:
  • have the specified types
• The representation:
  • defines a continuous region
  • consists of connected elementary space portions

6     Performance Assessment