A home battery survey. From your iPhone.

Walk the wall around your electric meter with an iPhone. The app measures it, and an installer checks the spot it suggests.

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Find your electric meter

A gray box with a round glass dial or a small screen, usually on an outside wall.

Hold your meter in the circle

Your phone takes the photo by itself.

Walk slowly to your right

Keep the wall and the ground in view. About 15 ft to go.

Walk slowly to your right

Keep the wall and the ground in view. About 10 ft to go.

Walk slowly to your right

Keep the wall and the ground in view. About 5 ft to go.

Is this the right end of the wall?

Aim where the wall stops or turns a corner, and tap Wall ends here.

What's at the right end?

This tells the installer whether the wall keeps going.

Tap the window's bottom-left corner

Put the circle on it and tap Mark, or tap it on screen.

Now tap its top-right corner

This is my meter

Mark somethingWall ends here

It turns a cornerSomething blocks it

CancelMark

What's on the ground along this wall?

The battery can only stand on some kinds of ground.

GrassMulchGravelConcreteDrivewayDeckNot sure

Anything else near your meter?

Gas meters, doors, windows, AC units, driveways and fences all change where a battery can go.

WindowAbout 6 ft right of your meter

Does this window open?

It opensIt stays shut

Looks complete

Sending your measurements

Keep the app open until this finishes.

Checking your wall

Measuring clearances around your meter.

An installer will take a look

12 ft right of your meter, 14 ft of cable

See it on your wall

An installer checks the measurements and suggested placement.

A closer spot may exist on the left of your meter. The scan didn't reach that side.

Your electrical panel still needs an electrician's review. This scan only covers where the battery can go.

What one walk records.

Seen

Measured

Placed

SeenA close-up of the meter, then the wall and ground to the corner.

MeasuredThe window, marked by two corners: 3 ft 3 in by 3 ft 7 in.

PlacedA possible spot 12 ft from the meter, for an installer to check.

What leaves the phone, and what comes back.

Needs a view? The app asks for it.
Walk and markThe iPhone tracks the wall and what it has seen.
Photos, poses and marksOne capture packet for the whole walk.
Placement rulesWritten rules, not a model. Each check passes, fails or stays unsure.
A spot, or one more viewUnsure checks ask for a better view.
See it on your wallIn AR. An installer reviews every result.

From camera frames to a wall in feet.

Four layers from ARKitEvery iPhone tracks the camera. LiDAR iPhones add depth and a mesh.

Select a layer to see what it adds.

On an iPhone with LiDAR, sceneDepth adds a distance for every pixel. Without it, the app works from images and poses alone.

ARKit detects the wall and the ground as planes. .gravity alignment points +y straight up, so the wall stands vertical in every frame.

The wall, measured in feetHouseScanKit puts every mark at s, feet along the wall from the meter.

What the phone writesThe wall, your marks, what the walk saw and each keyframe's pose, in one small file.

scene.jsonAbridged, example values

{
  "meter": {
    "pos": [0.0, 4.6, 0.0],
    "wall_id": "front"
  },
  "walls": [{
    "id": "front",
    "baseline": [[-2.5, 0], [14.8, 0]]
  }],
  "objects": [{
    "type": "window",
    "wall_id": "front",
    "span_ft": [4.6, 7.9],
    "attrs": { "operable": false },
    "source": "tap"
  }],
  "coverage": { "observed": [{
    "band": "ground",
    "span_ft": [-2.5, 14.8],
    "out_ft": 6.0
  }] },
  "keyframes": [{
    "img": "k9.jpg",
    "pose": [1, 0, 0, 0,
             0, 1, 0, 0,
             0, 0, 1, 0,
             9.0, 4.8, 6.0, 1]
  }]
}

The server rebuilds the wall from the photos.

The capture packet carries each photo with its ARKit pose, LiDAR depth when the phone has it, and your taps. The server measures the wall in 3D, checks the rules and answers with a spot or the view it still needs.

Capture packetPhotos, poses and depth upload in stages; finalizing starts the run.POST /v1/captures
Metric reconstructionCOLMAP refines ARKit's poses. Depth comes from LiDAR or π³, scale from LiDAR or the meter.poses · scale · dense
Scene and rulesWalls, ground, equipment and what was actually seen. Rules decide; other checks can only veto or downgrade.scene · criteria
ResultA spot for an installer to review, or the views still needed, placed in AR.GET …/result

GET …/eventsProgress from each stage, back to the phone

result.jsonAbridged, example values

{
  "status": "needs_views",
  "outcome": {
    "kind": "needs_more_photos",
    "viewsNeeded": [{
      "id": "vn1",
      "kind": "band",
      "band": "ground",
      "side": "left",
      "sM": [-1.8, -0.2],
      "viewingAngleDeg": [20, 60]
    }]
  },
  "criteria": [{
    "id": "route_length",
    "outcome": "pass",
    "measuredFt": 14.0,
    "plusMinusFt": 0.6,
    "coverage": "observed"
  }]
}

Unseen ground stays unsure.

The walk went right, so the ground left of the meter was never seen. Drag across the wall to show it, and the checks settle.

A closer spot, 5 ft left of the meter

Not here

Wall behind itPass
Ground under itPass
Clear spaceFail

Rule limitEstimate and its error

The research behind the pipeline.

The briefing compares LiDAR reconstruction, learned depth and world models, with the tests behind each.

Read the briefing The project on GitHub