Calibration markers

Print a marker card and include it in your scene photo or video. PackOps detects the marker automatically and applies real-world scale to the captured object — no more guessing at dimensions, no manual two-click calibration.

Each print is unique. Every download mints its own serial & QR, so each physical card can be individually self-measured for true scale — reprint any time for a fresh, distinct card. Every color is a distinct marker at the same size, so several cards can share one photo without colliding — carry a size in two or three colors. Sign in to print a tracked marker.

Aruco marker cards (imperial / US) — US Letter

Inch-native scale anchors for US packaging plants. Print, cut, and place in the scene. Auto-detected on upload. Measure with an inch ruler — no conversion.

Print at 100% scale. Choose “Actual Size” in your print dialog — do not use “Fit to Page”. Verify the printed marker edge matches its labelled size with an inch ruler. Do NOT use a metric ruler and convert. Unit conversion drift breaks the calibration.
1-1/4" marker
Small product, tabletop scans
Capture distance 0.2 m to 2.5 m
Format Two-sided trim card · LETTER
2" marker
Medium product, retail packaging
Capture distance 0.3 m to 4 m
Format Two-sided trim card · LETTER

Aruco marker cards (metric) — A4

Millimetre-native scale anchors. Print, cut, and place in the scene. Auto-detected on upload. Measure with a metric ruler.

Print at 100% scale. Choose “Actual Size” in your print dialog — do not use “Fit to Page”. Verify the printed marker edge matches its labelled size with a metric ruler. Do NOT use an inch ruler and convert. Inch-to-millimeter conversion drift breaks the calibration.
30 mm marker
Small product, tabletop scans
Capture distance 0.2 m to 2.5 m
Format Two-sided trim card · A4
PackOps Mobile users: these markers are also available under Settings → Calibration on the iOS app. Download here on any device.

ChArUco boards — sign-shop print (Dibond)

Room-scale calibration boards (DICT_4X4_1000). Each color is a distinct marker-id range, so two boards of different colors can share one scene. Mint a serial, send the PDF to a sign shop: 3 mm Dibond, direct UV print, matte, no laminate — the full shop guide is page 2 of every PDF. Print at 100% scale and verify a square edge with the ruler named on the sheet.

17.5 × 12.5 in board · Imperial / US
ChArUco 7 × 5 @ 2.5 in squares · camera calibration + room-scale capture anchor
Format 2-page sign-shop PDF (cut line, crop marks, handle slot)
35.75 × 24.75 in board · Imperial / US
ChArUco 13 × 9 @ 2.75 in squares · camera calibration + room-scale capture anchor
Format 2-page sign-shop PDF (cut line, crop marks, handle slot)
490 × 350 mm board · Metric
ChArUco 7 × 5 @ 70 mm squares · camera calibration + room-scale capture anchor
Format 2-page sign-shop PDF (cut line, crop marks, handle slot)
975 × 675 mm board · Metric
ChArUco 13 × 9 @ 75 mm squares · camera calibration + room-scale capture anchor
Format 2-page sign-shop PDF (cut line, crop marks, handle slot)

Expected scale accuracy

Scale error as a percentage of measured length, by marker size, camera distance, and sensor resolution (assumes a ~70° wide phone camera, ~0.5 px corner detection). Error roughly halves at higher resolution — use your phone’s highest-resolution still mode. Calibrating the printed marker (a ruler in your card’s unit + two photos) removes the separate ±1–3% print-scale error on top of this. These figures are unit-agnostic (scale error is a percentage): the imperial cards map to the nearest row — 1″ ≈ 30 mm, 2″ ≈ 50 mm, 4″ ≈ 100 mm.

30 mm marker
Camera distance12 MP24 MP48 MP
0.5 m±0.29%±0.19%±0.15%
1 m±0.58%±0.39%±0.29%
2 m±1.16%±0.77%±0.58%
50 mm marker
Camera distance12 MP24 MP48 MP
1 m±0.35%±0.23%±0.18%
2 m±0.69%±0.46%±0.35%
3 m±1.04%±0.69%±0.53%
100 mm marker
Camera distance12 MP24 MP48 MP
1 m±0.17%±0.12%±0.09%
3 m±0.52%±0.35%±0.26%
5 m±0.87%±0.58%±0.44%

ChArUco demo board — sign-shop print, high precision

For sales-rep capture sessions and high-value-customer dimensioning visits. Sub-pixel chessboard-corner detection plus on-device camera calibration give roughly 5× tighter scale precision than the Aruco markers above. Trimmed board is 1.10 × 0.65 m (functional 1 × 0.5 m chessboard plus margins); prints direct-to-Dibond at a sign shop — lightweight, dead flat, survives the trunk of a car. Cut line + corner crop marks + CNC handle slot included.

ChArUco demo board v1 — 1.10 × 0.65 m trimmed (2-page PDF)

Functional area 1000 × 500 mm (10 × 5 squares at 100 mm, markers 70 mm, DICT_4X4_50), with a 50 mm margin on the top + sides, a 100 mm info strip at the bottom, and 10 mm bleed with corner crop marks. Spec, print-verify warning, and placement / capture instructions are printed directly on the board; full sign-shop + handling guide is page 2.

  • Print at 100% scale on Dibond (3 mm aluminum composite) via a sign shop, direct UV print. About $60-120 single-pass.
  • Trim along the cut line (corner crop marks), then CNC-cut the handle slot indicated on the board.
  • Object footprint up to about 0.4 m: lay board under the object.
  • Object up to about 2 m (0.75 m and 1 m cubes): lay board beside the object, parallel to one face, 20-30 cm clear floor gap.
  • Walk-around multi-view capture. Board doesn't need to be in every frame — LiDAR carries the pose, board re-anchors when visible.
  • Optional 30 s session-start camera-calibration pass yields 0.2-0.5% additional precision over factory-default phone-camera intrinsics.
Download board PDF
Take this PDF to a sign shop. Specify Dibond (or similar aluminum composite, 3 mm), direct UV print, 100% scale, single piece.
How it works. Each PDF contains an Aruco fiducial marker — a square black-and-white pattern that PackOps detects in your scene photos using OpenCV. The marker's known physical size (printed at 100%) gives PackOps the conversion from on-screen pixels to real-world millimeters, so any object captured alongside it is scaled correctly.

For best accuracy: set your phone camera to its highest-resolution still mode (48 MP or higher if available). Error approximately halves versus 12 MP — see the Expected scale accuracy table above for the numbers at each marker size, distance, and resolution.