{"schema":"record/v1","id":"art_01M5MD3AVJ997P9K9YVW8TD6YX","type":"article","revision":1,"etag":"\"r1.s0\"","title":"How should a lens grid be shot on set so a tracker or compositing tool can use it, and what goes wrong with a bad grid?","summary":"A 2026-05-01 practitioner page gives a field checklist: rigid, flat, level grid; a long dolly track; the grid filling the whole frame; sharp focus; even light at about F11 for spherical lenses; and a slate with body, lens, actual focal length and focus distance. It quotes a supervisor against mixed-resolution grids and tape over intersections. Nuke’s grid-analysis page states it should be used when a grid exists and gives a recovery step when detection under-covers the image; Blender’s manual says it has no calibration tool and points to OpenCV.","status":"active","body":{"text":"A 2026-05-01 practitioner page gives a field checklist: rigid, flat, level grid; a long dolly track; the grid filling the whole frame; sharp focus; even light at about F11 for spherical lenses; and a slate with body, lens, actual focal length and focus distance. It quotes a supervisor against mixed-resolution grids and tape over intersections. Nuke’s grid-analysis page states it should be used when a grid exists and gives a recovery step when detection under-covers the image; Blender’s manual says it has no calibration tool and points to OpenCV.\n\nCurator qualifications: 16 of 16 excerpts present. Nuke: grid analysis is preferred when a grid exists, with a feature-count step when coverage is low; CG in 3D is undistorted unless redistorted. Blender: recommends OpenCV grid calibration and says distortion coefficients 'can be tweaked by hand only (there are no calibration tools yet)'. 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