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

1      Definition

Visual Geometry is a Visual Data Type representing the boundary  of a spatial entity using explicitly defined geometric primitives.

A Visual Geometry SHALL define:

  • a surface representation
  • a set of geometric elements
  • structural relationships enabling reconstruction of the surface

2      Functional Requirements

The Visual Geometry Data Type SHALL support the following formats:

  • Triangle Mesh
  • Polygon Surface
  • NURBS Surface

Each format SHALL conform to:

  • Functional Requirements
  • Format Specification
  • Semantic Definitions

All Visual Geometry formats:

  • SHALL define a surface (wrapper)
  • SHALL include:
    • explicit geometric elements
    • connectivity or parametric structure
  • SHALL support:
    • reconstruction of the surface
  • MAY include:
    • normals
    • texture coordinates
  • SHALL be:
    • machine-parsable
    • self-contained

3      Syntax

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

4      Semantics

Label Description
Header Visual Geometry Header – Standard “VIS-VGM-Vx.y”
MInstanceID Identifier of a virtual space including the location represented by Simple Location.
UEnvironmentID Identifier of a real space including the location represented by Simple Location.
VisualGeometryID Identifier of this Visual Geometry instance.
GeometryType Type of geometric representation (TriangleMesh, PolygonSurface, NURBSSurface).
GeometryData Data structure encoding the geometry according to GeometryType.
Boundary The surface separating interior from exterior defined by the geometry.
Connectivity Structural relationships between geometric elements enabling reconstruction of the surface.
Triangle Mesh Section grouping semantics specific to Triangle Mesh format.
Vertices Array of 3D coordinates defining points in space.
Faces Triplets of vertex indices defining triangular elements.
Normals Vector directions associated to vertices.
FaceNormals Mapping from faces to normal indices.
TexCoords 2D coordinates for texture mapping.
VertexTexCoordIndex Mapping from vertices to texture coordinates.
Connectivity Defined by shared vertex indices across faces.
Boundary Union of all triangles not shared by two adjacent faces.
Closure Property indicating whether the mesh forms a watertight surface.
ManifoldStatus Property indicating whether edges belong to exactly two faces.
Polygon Surface Section grouping semantics specific to Polygon Surface format.
Vertices Array of 3D coordinates defining points in space.
Faces Lists of vertex indices defining polygon boundaries.
Normals Optional vectors defining surface orientation.
Connectivity Derived from shared edges between polygons.
SurfaceContinuity Property indicating continuity across polygon boundaries.
Planarity Property indicating whether polygons lie in a plane.
Boundary Edges belonging to a single face.
NURBS Surface Section grouping semantics specific to NURBS Surface format.
ControlPoints Weighted points defining surface shape.
DegreeU Polynomial degree along U parameter.
DegreeV Polynomial degree along V parameter.
KnotU Knot vector defining parameterization in U.
KnotV Knot vector defining parameterization in V.
SurfaceDefinition Parametric function mapping (u,v) to 3D space.
Continuity Smoothness level across parameter domain.
ClosureU Indicates periodicity along U direction.
ClosureV Indicates periodicity along V direction.
EvaluationDomain Range of parameters where surface is defined.
Boundary Curves defined at the parameter domain limits.
DataXMData Information about this Visual Geometry instance.
DescrMetadata Descriptive Metadata.

5     Conformance Testing

A location instance Conforms with Visual Geometry (OSD-VGM) if:

  1. The Data validates against the Visual Geometry’s JSON Schema.
  2. All Data in the  Visual Geometry’s JSON Schema have the specified types.

6     Performance Assessment