Calibration markers

Print a marker 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.

Aruco markers — print at home or office

Single-marker scale anchors for everyday capture. Print on US Letter or A4, cut, and place in the scene. Auto-detected on upload.

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 0.5 m to 2 m

Format Two-sided trim card

US Letter A4

50 mm marker

Medium product, retail packaging

Capture distance 1 m to 3 m

Format Two-sided trim card

US Letter A4

100 mm marker

Large product, half-step back

Capture distance 1 m to 5 m

Format Two-sided trim card

US Letter A4

PackOps Mobile users: these markers are also available under Settings → Calibration on the iOS app. Download here on any device.

Small ChArUco board — printable, high precision

A desktop / printer-friendly chessboard of Aruco markers (5 × 7, DICT_4X4_50). Dual purpose: calibrate your phone camera (wave it over the board ~30 s) and use it as a print-scale self-measure target. Sub-pixel corner detection beats a single marker for precision at close range. Mount it dead flat. Two-sided trim card.

5 × 7 board

Camera calibration + precision self-measure target

Squares 32 mm (Letter) / 34 mm (A4)

Format Two-sided trim card

US Letter A4

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 (metric ruler + two photos) removes the separate ±1–3% print-scale error on top of this.

30 mm marker
Camera distance	12 MP	24 MP	48 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 distance	12 MP	24 MP	48 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 distance	12 MP	24 MP	48 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.