# Use 01Spatial Reference Boards

The **01Spatial Reference Board** is a printable ChArUco pattern. It tells the system how long one meter is in the real site, where the map origin is, and which direction is up. You may use no boards or place several according to the space; the current official kit contains ten uniquely numbered boards. If boards cannot be placed, scan normally and configure surveyed GCPs (**Ground Control Points**) in Map Configurator after parsing. Despite the name, a GCP does not have to be on the floor.

> **A reliable real-world size and orientation require one of these methods:** use Reference Boards during capture, or [configure surveyed GCPs in Map Configurator](/tutorials/mapping/panorama-camera-video/map-configurator) afterward. Do not skip both methods.

[![Preview of 01Spatial Reference Board #0 in A4 format, with a uniquely encoded ChArUco pattern and print verification ruler](/media/docs/spatial-reference-boards/01spatial-reference-board-a4-preview.png)](/media/docs/spatial-reference-boards/01spatial-reference-board-a4-preview.png)

## Why a physical reference is required

Images can recover spatial structure, but images alone do not independently prove real-world scale, origin, or orientation. A coherent point cloud does not prove that one meter in the map is exactly one meter in the site.

Reference Boards introduce known dimensions and stable corners into the video. Map Configurator provides equivalent physical evidence through surveyed GCPs and distances. Either route gives the map a **verifiable, reviewable real-world reference** instead of judging accuracy from appearance alone.

## Choose how many boards to prepare

| Quantity | Best for | Recommendation |
| --- | --- | --- |
| **0** | Boards cannot be placed on site | Scan normally, then configure GCPs in Map Configurator |
| **1** | Small spaces or a quick validation | Print and use **datum board #0** only; it establishes a reference but cannot cross-check scale between boards |
| **2–10** | Production projects, recommended | Use **datum board #0** plus uniquely numbered helper boards for stronger scale checks and cross-area continuity |

If you choose the board route, **board #0 is required**. Never print the same page twice and treat the copies as different boards; duplicate IDs make different physical locations indistinguishable. Use either the A4 or A0 kit within one project, not matching IDs from both kits.

## Download the official print files

| Kit | Recommended setting | Suggested 360° camera distance | Download |
| --- | --- | --- | --- |
| **A4 · 10 pages** | Small rooms, work areas, nearby indoor capture | About 1.5–2.5 m | [Download the A4 Reference Board PDF](/media/docs/spatial-reference-boards/01spatial-reference-boards-a4.pdf) |
| **A0 · 10 pages** | Halls, factories, outdoor and larger spaces | About 6–12 m | [Download the A0 Reference Board PDF](/media/docs/spatial-reference-boards/01spatial-reference-boards-a0.pdf) |

The current kit supports up to ten ready-to-print boards. Contact 01Spatial for a dedicated kit when you need more IDs or a larger format; do not duplicate an existing page.

## Print at true physical size

1. Select **Actual size / 100%** in the print dialog. Disable **Fit to page**, **Scale to fit**, and other automatic scaling.
2. Measure the verification line printed at the bottom of every page: **150 mm** for A4 or **200 mm** for A0. Do not use a print with a different measurement; correct the print scale and print it again.
3. Use matte paper and mount the full sheet on a flat, rigid backing. Curling, bent edges, and glossy reflections reduce corner accuracy.
4. Preserve the complete white border and pattern. Do not crop, draw on, fold, or cover the encoded area.

## Place the boards on site

### Place datum board #0

Place **#0** flat near the scan start, at a stable location with a clear meaning for the project. It is the primary reference used to establish the spatial datum. Do not move or rotate it before capture is complete.

### Place helper boards

Distribute selected boards #1–#9 near doorways, corners, the middle of long corridors, weak-texture surfaces, and transitions between areas. A board may be laid flat or mounted upright, but it must remain flat, fixed, visible, and unobstructed. Adjacent areas should share a visible board or enough static visual texture.

> Reference Boards provide real-world size and a stable reference; they do not need to cover every square meter. Large-site continuity still comes from continuous capture, sufficient overlap, and loop closure.

## Capture every board clearly

- Slow down near each board. Keep the complete board sharp, free of glare, and roughly one quarter of the image.
- Capture every board from multiple positions and angles; **board #0 should be clearly visible from at least four different positions**.
- Do not flash past a board at an extreme oblique angle, and do not cover it with the operator, pole, or camera.
- Pass board #0 or a helper near the starting area again at the end of the route to create a verifiable loop.
- If a board moves, bends, or becomes occluded, do not treat observations from before and after the change as one reference. Restore the site and recapture.

## Confirm the route after upload

After Portal parses the video, it detects boards and evaluates their observation quality. Select **Build with ChArUco**—the automatic Reference Board route—only when the parse result confirms that board IDs, sharpness, multi-view coverage, and geometric consistency passed the gate.

If no board was placed, too few observations were detected, or any quality gate failed, add GCPs in [Map Configurator](/tutorials/mapping/panorama-camera-video/map-configurator). Seeing a board in the video does not prove that the automatic route was accepted; follow the Portal parse result. Choose one route only and do not submit two competing world-coordinate definitions.

## Pre-scan checklist

- [ ] One spatial-reference route is selected: Reference Boards or Map Configurator.
- [ ] The board route includes #0, every board ID is unique, and matching A4/A0 IDs are not mixed.
- [ ] Prints are at 100% actual size; the 150 mm A4 or 200 mm A0 verification line measures correctly.
- [ ] Every board is flat, matte, fixed, visible, and will not move during capture.
- [ ] The route sees every board clearly from several positions, with at least four clear views of #0.
- [ ] If no boards are used, at least three reliable GCPs will be configured in Map Configurator after parsing.

When parsing completes, use the automatic board route if Portal accepts it; otherwise continue to [Configure scan data](/tutorials/mapping/panorama-camera-video/map-configurator).