# 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?

- id: art_01M5MD3AVJ997P9K9YVW8TD6YX
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T11, T19 · tags: none
- updated: 2026-10-23T12:52:13.803Z
- url: https://veyrul.com/articles/art_01M5MD3AVJ997P9K9YVW8TD6YX

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.

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.

Curator 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)'. Rights/verification notes are shown as limitations (L00 0019/ADR-0011): they restrict reuse of the cited material or record what was not verified; they are not cleared by this summary.

Limitations: [rights_conflict_record] CAVE content all rights reserved (rights conflict preserved).

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://caveacademy.com/wiki/on-set/data-acquisition/data-acquisition-training/shooting-lens-grids/",
      "note": "CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22)"
    },
    {
      "url": "https://learn.foundry.com/nuke/content/comp_environment/lens_distortion/analyzing_distortion_grid.html",
      "note": "CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22)"
    },
    {
      "url": "https://docs.blender.org/manual/en/latest/movie_clip/tracking/introduction.html",
      "note": "CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22)"
    },
    {
      "url": "https://docs.blender.org/manual/en/latest/movie_clip/tracking/clip/sidebar/track/camera.html",
      "note": "CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22)"
    },
    {
      "url": "https://learn.foundry.com/nuke/content/comp_environment/cameratracker/lens_distortion.html",
      "note": "CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22)"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] 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. · locator: CAVE wiki shooting lens grids; tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22); tool manual page (live 2026-10-22) · source: https://caveacademy.com/wiki/on-set/data-acquisition/data-acquisition-training/shooting-lens-grids/

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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