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Definition
Functional Requirements
Syntax
Semantics
Conformance Testing
Performance Assessment

1 Definition

What a surface is made of, as far as it acts on what reaches it: for sound, the fractions of energy it absorbs, scatters and lets through. Each fraction by frequency band; a renderer maps the bands given onto its own (for example 400 Hz, 2.5 kHz and 15 kHz).

2 Functional Requirements

  1. The Data shall have Header “OSD-MTR-V1.5”.
  2. The Data shall include MaterialID.
  3. The Data may include the other properties of Table 1, each as specified there.
  4. The Data shall validate against the JSON Schema of Section 3.

3 Syntax

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

4 Semantics

Table 1 – Semantics of the Material Data Type

Label
Description
Header Material Header – Standard “OSD-MTR-Vx.y”.
MInstanceID
UEnvironmentID
MaterialID (required)
MaterialTime (SimpleTime)
Acoustic How the surface acts on sound.
– Absorption Fraction of the sound energy reaching the surface that it absorbs. (ByBand)
– Scattering Fraction of the reflected energy scattered in random directions: 0 a mirror-like reflection, 1 a fully diffuse one. Range 0..1.
– Transmission Fraction of the sound energy reaching the surface that passes through it. (ByBand)
– BandScheme The bands the per-band values are given in, by their centre frequencies: octave bands, one-third-octave bands, or others. One of: Octave, ThirdOctave, Other.
– Incidence How the values were measured or estimated: for sound arriving from all directions (random incidence, as in a reverberation room, ISO 354), or perpendicular to the surface (normal incidence, as in an impedance tube, ISO 10534). Values of different incidence are not directly comparable. One of: Random, Normal.
DataXMData (DataExchangeMetadata)
DescrMetadata

5 Conformance Testing

A Data instance conforms with Material (OSD-MTR) if it validates against the JSON Schema of Section 3. If a schema contains references to other schemas, conformance of data for the primary schema implies that any data referencing a secondary schema shall also validate against the relevant schema.

6 Performance Assessment

Not part of this specification.

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