MPEG_viewport_recommended

Contributors

  • ISO/IEC SC29 WG3 (MPEG Systems) - Scene Description Breakout Group
  • Contacts
    • Thomas Stockhammer (MPEG-I Scene Description BoG Chair, tsto@qti.qualcomm.com)

Status

Based on ISO/IEC FDIS 23090-14

Dependencies

Written against the glTF 2.0 spec.

Overview

MPEG_viewport_recommended provides the link from a camera object defined in glTF 2.0 to recommended viewport information by referencing to the timed accessor, where the sample of recommended viewport information will be made available.

The recommended viewport information provides dynamically changing information which includes translation and rotation of the node which includes the camera object, as well as the intrinsic camera parameter of the camera object. The client renders viewport according to the dynamically changed information.

NOTE: Another approach to achieve recommended viewport is to define an animation for a node with attached camera. The approach, however, does not support dynamically changing intrinsic camera and must be defined during the creation of glTF object.

MPEG_viewport_recommended Properties

  Type Description Required
viewports MPEG_viewport_recommended.viewport [1-*]   ✓ Yes
extensions object JSON object with extension-specific objects. No
extras any Application-specific data. No

Additional properties are allowed.

MPEG_viewport_recommended.viewports

MPEG_viewport_recommended.extensions

JSON object with extension-specific objects.

  • Type: object
  • Required: No
  • Type of each property: Extension

MPEG_viewport_recommended.extras

Application-specific data.

  • Type: any
  • Required: No

MPEG_viewport_recommended.viewport

specifying a recommended viewport.

MPEG_viewport_recommended.viewport Properties

  Type Description Required
name string The user-defined name of this object. No
translation integer Provides a reference to accessor No
rotation integer Provides a reference to accessor No
type string provides the type of camera. No, default: "perspective"
parameters integer Provides a reference to accessor No
extensions object JSON object with extension-specific objects. No
extras any Application-specific data. No

Additional properties are allowed.

MPEG_viewport_recommended.viewport.name

The user-defined name of this object. This is not necessarily unique, e.g., an accessor and a buffer could have the same name, or two accessors could even have the same name.

  • Type: string
  • Required: No

MPEG_viewport_recommended.viewport.translation

Provides a reference to accessor where the timed data for the translation of camera object will be made available. The componentType of the referenced accessor shall be FLOAT and the type shall be VEC3, (x, y, z).

  • Type: integer
  • Required: No
  • Minimum: ` >= 0`

MPEG_viewport_recommended.viewport.rotation

Provides a reference to accessor where the timed data for the rotation of camera object will be made available. The componentType of the referenced accessor shall be FLOAT and the type shall be VEC4, as a unit quaternion, (x, y, z, w).

  • Type: integer
  • Required: No
  • Minimum: ` >= 0`

MPEG_viewport_recommended.viewport.type

provides the type of camera.

  • Type: string
  • Required: No, default: "perspective"
  • Allowed values:
    • "perspective"
    • "orthographic"

MPEG_viewport_recommended.viewport.parameters

Provides a reference to accessor where the timed data for the perspective or orthographic camera parameters will be made available. The componentType of the referenced accessor shall be FLOAT and the type shall be VEC4. When the type of the camera object which includes this extension is perspective, FLOAT_VEC4 means (aspectRatio, yfov, zfar, znear). When orthographic type, FLOAT_VEC4 means (xmag, ymag, zfar, znear). The requirements on the camera parameters from ISO/IEC 12113:2021 shall apply.

  • Type: integer
  • Required: No
  • Minimum: ` >= 0`

MPEG_viewport_recommended.viewport.extensions

JSON object with extension-specific objects.

  • Type: object
  • Required: No
  • Type of each property: Extension

MPEG_viewport_recommended.viewport.extras

Application-specific data.

  • Type: any
  • Required: No

Known Implementations

Resources

  • ISO/IEC FDIS 23090-14, Information technology — Coded representation of immersive media — Part 14: Scene Description
  • ISO/IEC WD 23090-24, Information technology — Coded representation of immersive media — Part 24: Conformance and Reference Software for Scene Description for MPEG Media

License

Copyright ISO/IEC 2022

The use of the “MPEG scene description extensions” is subject to the license as accessible here: https://standards.iso.org/ and is subject to the IPR policy as accessible here: https://www.iso.org/iso-standards-and-patents.html.