8.2 Material schema

8.2.1 metadata

The key meta information about the material properties.

Type: object
Required: Yes

8.2.1.1 name

The display name of the material, such as 'Red brick' or 'Dark asphalt'.

Type: string
Required: Yes

8.2.1.2 description

Short description of the material in 2 - 3 sentences.

Type: string
Required: No

8.2.1.3 uuid

Universally unique identifier for the material in 8-4-4-4-12 format, see en.wikipedia.org/wiki/Universally_unique_identifier. The uuid stays the same, even if version is updated.

Type: string
Pattern: \\b[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\\b$
Required: Yes

8.2.1.4 materialVersion

The version number of the material, following semantic versioning (e.g., '1.0.0').

Type: string
Pattern: ^\\d+\\.\\d+\\.\\d+$
Required: Yes

8.2.1.5 openMaterialVersion

The version of the OpenMATERIAL 3D specification used, adhering to semantic versioning (e.g., '1.0.0').

Type: string
Pattern: ^\\d+\\.\\d+\\.\\d+$
Required: Yes

8.2.1.6 copyright

Indicates copyright details, including the year and copyright holder (e.g., '© 2024 ACME Inc.').

Type: string
Required: Yes

8.2.1.7 license

Describes the license for material distribution. Use an SPDX identifier for open-source licenses (e.g., 'MIT'), or provide a URL or filename for proprietary licenses.

Type: string
Required: Yes

8.2.1.8 author

Lists the author(s) of the material as a name, email, or company. Multiple authors should be comma-separated.

Type: string
Required: Yes

8.2.1.9 creationDate

The date and time of material creation, formatted as YYYYMMDDTHHMMSSZ according to ISO 8601 (e.g., '20240703T101728Z').

Type: string
Pattern: ^\\d{8}T\\d{6}Z$
Required: No

8.2.2 materialProperties

Properties related to the material.

Type: object
Required: Yes

8.2.2.1 surfaceRoughness

Information about the surface roughness of the material.

Type: object
Required: No

8.2.2.1.1 surfaceHeightRms

Root mean square of surface height deviations, called RMS-Roughness, being a vertical measure of roughness and given in meters.

Type: number
Required: Yes

8.2.2.1.2 surfaceCorrelationLength

Correlation length of the surface height deviations, being the distance after autocorrelation function has dropped to 1/e. Thus being a horizontal measure of roughness and given in meters.

Type: number
Required: Yes

8.2.2.1.3 source

Source of the surface roughness data.

Type: string
Required: Yes

8.2.2.2 emissivityData

Emissivity data of the material

Type: object
Required: No

8.2.2.2.1 emissivityCoefficient

Emissivity describes the ability to emit energy as thermal radiation. Given as the fraction of thermal radiation emitted by a surface relative to the radiation emitted by an ideal black body at the same temperature. Here the hemispherical total emissivity is used which considers full emission over all wavelengths, directions and polarization for a given particular temperature: ε(T).

Type: number
Required: Yes

8.2.2.2.2 temperature

Temperature of material in Kelvin [K] at which the emissivity is measured.

Type: number
Required: Yes

8.2.2.2.3 source

Source of the emissivity data.

Type: string
Required: Yes

8.2.2.3 elasticityData

Information about the elasticity of the material.

Type: object
Required: No

8.2.2.3.1 youngsModulus

Young’s modulus of the material in Pa.

Type: number
Required: Yes

8.2.2.3.2 poissonsRatio

Poisson’s ratio of the material.

Type: number
Required: Yes

8.2.2.3.3 source

Source of the elasticity data.

Type: string
Required: Yes

8.2.2.4 densityData

Information about the density of the material.

Type: object
Required: No

8.2.2.4.1 density

Density of the material in kg/m^3.

Type: number
Required: Yes

8.2.2.4.2 source

Source of the density data.

Type: string
Required: Yes

8.2.2.5 retroreflectivityData

Information about the retro-reflective properties of the material in the visible light spectrum.

Type: object
Required: No

8.2.2.5.1 coefficientOfRetroreflection

Coefficient of retro-reflection in cd lx^-1 m^-2.

Type: number
Required: Yes

8.2.2.5.2 source

Source of the retro-reflectivity data.

Type: string
Required: Yes

8.2.2.6 electromagneticPropertiesUri

Relative path to a property lookup table file with electromagnetic material properties.

Type: string
Pattern: .*_emp\\.xompt$
Required: No

8.2.2.7 opticalPropertiesUri

Relative path to a property lookup table file with optical material properties.

Type: string
Pattern: .*_optical\\.xompt$
Required: No

8.2.2.8 brdfUris

Relative paths to one or multiple property lookup table files with wavelength-dependent bidirectional reflectance distribution functions.

Type: array
Required: No

8.2.2.9 reflectanceUris

Relative paths to one or multiple property lookup table files with wavelength-dependent reflectance values.

Type: array
Required: No

8.2.2.10 customProperties

Non-standardized material properties for custom tools or tool chains.

Type: object
Required: No