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Composition

Asset composition defines how different types of content relate to each other within MVMD metadata. Understanding these relationships is crucial for creating well-structured, maintainable metadata for complex assets.

Primary Entity (mainEntity)​

Schema.org: Thing > Property :: about : mainEntity

The mainEntity property identifies the primary subject or focus of a metadata object. This is particularly useful when one object serves to describe or represent another.

Basic Usage​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "ImageObject",
  "name": "Character Preview",
  "contentUrl": "https://example.com/preview.jpg",
  "thumbnail": "https://example.com/preview-thumb.jpg",
  "mainEntity": {
    "@type": "3DModel",
    "name": "Hero Character",
    "contentUrl": "https://example.com/character.glb",
    "encodingFormat": "model/gltf-binary"
  }
}

Common Use Cases​

  • Preview images describing 3D models
  • Documentation describing an asset
  • Thumbnail representing a larger work
  • Landing page for a virtual location

Component Parts (hasPart)​

Schema.org: Thing > Property :: hasPart

The hasPart property defines direct components or pieces that make up a larger asset. This is crucial for describing modular or composite assets.

Component parts are mentioned in further detail in the composable page of the implementation section.

Basic Structure​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "CreativeWork",
  "name": "Modular Vehicle",
  "hasPart": [
    {
      "@type": "3DModel",
      "name": "Chassis",
      "contentUrl": "https://example.com/chassis.glb",
      "position": "base"
    },
    {
      "@type": "3DModel",
      "name": "Body",
      "contentUrl": "https://example.com/body.glb",
      "position": "attachment"
    }
  ]
}

Nested Components​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "CreativeWork",
  "name": "Complex Assembly",
  "hasPart": [
    {
      "@type": "CreativeWork",
      "name": "Main Module",
      "hasPart": [
        {
          "@type": "3DModel",
          "name": "Base Component",
          "contentUrl": "https://example.com/base.glb"
        },
        {
          "@type": "3DModel",
          "name": "Top Component",
          "contentUrl": "https://example.com/top.glb"
        }
      ]
    }
  ]
}

Common Use Cases​

  • Modular assets
  • Complex assemblies
  • Multi-part environments
  • Composite objects

Associated Media (associatedMedia)​

Schema.org: Thing > Property :: associatedMedia

The associatedMedia property links to related media assets that support or enhance the main asset.

Basic Usage​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "3DModel",
  "name": "Interactive Display",
  "contentUrl": "https://example.com/display.glb",
  "associatedMedia": [
    {
      "@type": "ImageObject",
      "name": "Texture Atlas",
      "contentUrl": "https://example.com/textures.jpg",
      "encodingFormat": "image/jpeg"
    },
    {
      "@type": "VideoObject",
      "name": "Usage Tutorial",
      "contentUrl": "https://example.com/tutorial.mp4",
      "encodingFormat": "video/mp4"
    },
    {
      "@type": "AudioObject",
      "name": "Sound Effects",
      "contentUrl": "https://example.com/sounds.mp3",
      "encodingFormat": "audio/mpeg"
    }
  ]
}

Common Use Cases​

  • Textures and materials
  • Supplementary media
  • Tutorial content
  • Preview content

Embedded Content (encodesCreativeWork)​

Schema.org: Thing > Property :: encodesCreativeWork

The encodesCreativeWork property indicates content that is embedded within or encoded by the main asset.

Basic Usage​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "3DModel",
  "name": "Information Kiosk",
  "contentUrl": "https://example.com/kiosk.glb",
  "encodesCreativeWork": [
    {
      "@type": "ImageObject",
      "name": "Screen Content",
      "contentUrl": "https://example.com/screen.jpg"
    },
    {
      "@type": "TextObject",
      "name": "Display Text",
      "contentUrl": "https://example.com/text.txt"
    }
  ]
}

Common Use Cases​

  • Screen content in 3D models
  • Embedded documents
  • Internal textures
  • Bundled resources

Schema.org: Thing > Property :: subjectOf

The subjectOf property links to documentation, descriptions, or other content about the asset.

Basic Usage​

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "3DModel",
  "name": "Complex Machinery",
  "contentUrl": "https://example.com/machine.glb",
  "subjectOf": [
    {
      "@type": "DigitalDocument",
      "name": "Technical Documentation",
      "url": "https://example.com/docs/technical.pdf",
      "encodingFormat": "application/pdf"
    },
    {
      "@type": "VideoObject",
      "name": "Assembly Guide",
      "contentUrl": "https://example.com/guides/assembly.mp4",
      "encodingFormat": "video/mp4"
    }
  ]
}

Common Use Cases​

  • Technical documentation
  • User guides
  • Assembly instructions
  • Educational content

Complete Composition Example​

Here's an example showing all composition types working together:

{
  "@context": {
    "@vocab": "https://schema.org/",
    "mvmd": "https://mvmd.org/v1/"
  },
  "@type": "ImageObject",
  "name": "Virtual Vehicle Preview",
  "contentUrl": "https://example.com/preview.jpg",
  "thumbnail":  "https://example.com/preview-thumb.jpg",
  "mainEntity": {
    "@type": "CreativeWork",
    "name": "Modular Vehicle",
    "hasPart": [
      {
        "@type": "3DModel",
        "name": "Chassis Base",
        "contentUrl": "https://example.com/chassis.glb",
        "associatedMedia": [
          {
            "@type": "ImageObject",
            "name": "Metal Texture",
            "contentUrl": "https://example.com/metal.jpg"
          }
        ]
      },
      {
        "@type": "3DModel",
        "name": "Interactive Dashboard",
        "contentUrl": "https://example.com/dashboard.glb",
        "encodesCreativeWork": [
          {
            "@type": "ImageObject",
            "name": "Display Graphics",
            "contentUrl": "https://example.com/display.jpg"
          }
        ]
      }
    ],
    "subjectOf": [
      {
        "@type": "DigitalDocument",
        "name": "User Manual",
        "url": "https://example.com/manual.pdf"
      }
    ]
  }
}

Best Practices​

  1. Clear Hierarchy

    • Use mainEntity for the primary subject
    • Keep component hierarchies logical
    • Group related media appropriately
    • Document relationships clearly

  2. Relationship Management

    • Choose appropriate relationship types
    • Avoid circular references
    • Maintain clear ownership
    • Document dependencies

  3. Resource Organization

    • Group related resources
    • Use consistent naming
    • Maintain clear structure
    • Plan for updates

  4. Documentation

    • Document all relationships
    • Explain complex structures
    • Provide usage guides
    • Maintain version history