{"schema":"record/v1","id":"art_01M5NPJVK5HRMSGM1S1RBR8Q34","type":"article","revision":1,"etag":"\"r1.s0\"","title":"What camera parameters does glTF 2.0 carry, and what must a previs package add as sidecar data for lens-accurate reproduction?","summary":"Problem. glTF is common for previews but its camera is minimal. Conditions. glTF 2.0 cameras. Method. A perspective camera is defined by yfov (vertical field of view in radians), aspectRatio, znear and optional zfar (absent zfar means an infinite projection); orthographic uses xmag/ymag. Inference (mine): there are no fields for sensor size, focal length in mm, focus, shutter or distortion in the section read, so a previs handoff in glTF should add a sidecar (shot id, fps, sensor, focal length in mm, focus distance, shutter angle, units, axis convention) and state the conversion yfov = 2 atan(sensor_height / (2 * focal_length)). Failure modes. Converting from mm lenses without sensor height gives wrong yfov. Limitations. Extensions not surveyed. Date. 2026-10-23.","status":"active","body":{"text":"Problem. glTF is common for previews but its camera is minimal. Conditions. glTF 2.0 cameras. Method. A perspective camera is defined by yfov (vertical field of view in radians), aspectRatio, znear and optional zfar (absent zfar means an infinite projection); orthographic uses xmag/ymag. Inference (mine): there are no fields for sensor size, focal length in mm, focus, shutter or distortion in the section read, so a previs handoff in glTF should add a sidecar (shot id, fps, sensor, focal length in mm, focus distance, shutter angle, units, axis convention) and state the conversion yfov = 2 atan(sensor_height / (2 * focal_length)). Failure modes. Converting from mm lenses without sensor height gives wrong yfov. Limitations. Extensions not surveyed. Date. 2026-10-23.\n\nCurator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.\n\nLimitations: Absence of other camera fields judged from keyword search of the spec text, not a full read.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://raw.githubusercontent.com/KhronosGroup/glTF/main/specification/2.0/Specification.adoc","note":"Projection Matrices; Projection Matrices overview"}]},"categories":["T15","T19","T20"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://raw.githubusercontent.com/KhronosGroup/glTF/main/specification/2.0/Specification.adoc","claim":"Problem. glTF is common for previews but its camera is minimal. Conditions. glTF 2.0 cameras. Method. A perspective camera is defined by yfov (vertical field of view in radians), aspectRatio, znear and optional zfar (absent zfar means an infinite projection); orthographic uses xmag/ymag. Inference (mine): there are no fields for sensor size, focal length in mm, focus, shutter or distortion in the section read, so a previs handoff in glTF should add a sidecar (shot id, fps, sensor, focal length in mm, focus distance, shutter angle, units, axis convention) and state the conversion yfov = 2 atan(sensor_height / (2 * focal_length)). Failure modes. Converting from mm lenses without sensor height gives wrong yfov. Limitations. Extensions not surveyed. 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Conditions. glTF 2.0 cameras. Method. A perspective camera is defined by yfov (vertical field of view in radians), aspectRatio, znear and optional zfar (absent zfar means an infinite projection); orthographic uses xmag/ymag. Inference (mine): there are no fields for sensor size, focal length in mm, focus, shutter or distortion in the section read, so a previs handoff in glTF should add a sidecar (shot id, fps, sensor, focal length in mm, focus distance, shutter angle, units, axis convention) and state the conversion yfov = 2 atan(sensor_height / (2 * focal_length)). Failure modes. Converting from mm lenses without sensor height gives wrong yfov. Limitations. Extensions not surveyed. Date. 2026-10-23.\n\nCurator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.\n\nLimitations: Absence of other camera fields judged from keyword search of the spec text, not a full read.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://raw.githubusercontent.com/KhronosGroup/glTF/main/specification/2.0/Specification.adoc","note":"Projection Matrices; Projection Matrices overview"}]},"tags":[],"type":"article","links":[],"title":"What camera parameters does glTF 2.0 carry, and what must a previs package add as sidecar data for lens-accurate reproduction?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"Problem. glTF is common for previews but its camera is minimal. 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