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How to use

1. Pick match points on the plan: things you can physically see on site and find in the model. Tap a dot, or use + Pick point on plan and tap a corner or edge of the model (it snaps).
2. START AR. Point the phone at the ground and move it slowly until the ring appears.
3. Walk to each point, put the crosshair exactly on it, hold still, tap CAPTURE.
4. After 2 points the model appears. Capture a 3rd to check it. Watch the light: under 3 cm, under 10 cm, worse: re-capture the worst point.
5. Tap Lock to pin the model while you walk around. Use Measure for quick distances (aim and tap MARK, or tap the screen on the spot).
6. The top-left panel shows the distance walked and the straight-line distance from the start and from each captured point, and once the model is placed, which way to go to the next point.
7. Size check: pick something of known size (HSS, door, a taped length), tap its two ends, and compare. If several checks agree that the phone reads more than 1 % long or short, the app warns you and offers a correction for measurements only. The model is never scaled. Re-capture match points if that happens.
8. Report saves a file with every capture, check and photo (time, phone position, results), as HTML (print to PDF from Chrome) and JSON. It is kept only in this browser tab, so export before closing.

Good match points

• Far apart: at least 2, ideally 3 or more spread around the whole work area (not in a line, not bunched up). Points 2 m apart give a poor angle; 20 m apart a good one.
• On the ground and sharp: footing or slab corners, embed plate corners or centres, anchor bolt groups, existing building corners, curb or gate posts.
• Best of all: a surveyor's stakes or nails with known offsets to the grid. Put them in points.json as type "stake".
• Grid lines are not on the ground, so do not use grid intersections unless something is physically marked there.

Honest accuracy note

• This is a visual check, not a survey. Do not set out anything from it.
• Phone tracking drifts about 1–2 % of the distance walked. If you walk 30 m away, expect 30–60 cm. Re-capture nearby points when you move far.
• Capture accuracy depends on aim: a few cm at best. Low light, plain concrete, shiny or wet surfaces make it worse.
• Small objects: phone depth on a 6 in HSS is only good to roughly ± 1/2 in (± 12 mm), which is 8 %. For size checks use the longest known dimension you have (a door, a 3 m taped line, a footing).
• GPS + compass rough start is good to metres and 10–20° only; always match points after.
• Utilities: never rely on this for buried services. Call Utility Safety Partners (Alberta) for locates before any ground disturbance.

Privacy

Everything stays in this browser. Nothing is uploaded or sent anywhere. No login.

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