Alignment

Alignment runs on a custom build of COLMAP. For the short version, see the First Run walkthrough.

Two stages

Alignment runs in two stages. Stage 1 solves a camera pose for every fisheye frame. Stage 2 finds and matches features on the pinhole tiles those poses produce, and that match graph is what training starts from.

Matcher

The matcher decides which image pairs COLMAP compares when searching for overlap. Pick it based on how the footage was captured:

• Sequential — compares each frame with its neighbours in capture order. Best for video, where consecutive frames overlap. Fast, and the right choice for most 360 clips.
• Exhaustive — compares every image against every other. Highest quality and the most robust for unordered photo sets, but the slowest, since the pair count grows with the square of the image count.
• Spatial — uses GPS to compare only images that were physically close. Fast and good quality when the footage has reliable GPS, and it also scales the splat to real-world size (with .osv files this is still experimental).

Sequential overlap

Overlap sets how many neighbours on each side of a frame the sequential matcher compares it with. Lower is faster; higher catches more of the scene when the camera moves quickly.

Loop detection

Sequential matching also checks whether the camera has come back to a place it has already seen. Recognising the same place closes the loop and removes the drift that otherwise builds up along a walk.

Lens priors

The app learns your camera's lens distortion on the first alignment and remembers it. In Auto mode it tries, in order:

1. Your camera's cached calibration — saved after the first successful alignment. Your camera's actual optics, so the best results.
2. Shipped presets — built-in lens data for known cameras (Insta360 X4/X5/X6, DJI Osmo 360, Avata 360, Antigravity A1), matched from the video's metadata.
3. Self-calibration — COLMAP estimates the distortion during alignment. Slower, but it works — and the result is cached for next time.

Setting	What it does
Auto (recommended)	Cache → preset → self-calibrate. Set and forget.
Camera model	Force a shipped preset (e.g. "Insta360 X5").
Custom	Enter lens parameters by hand. Advanced users only.
Off	Always self-calibrate. Slower — geometry appears after 10+ min instead of instantly.

Global mapper (GLOMAP)

Default: ON. Solves all camera positions at once instead of registering frames one by one — 10–100× faster.

Leave it on. The first clip from a new camera automatically uses the slower incremental mapper to learn the lens, then all later clips use GLOMAP. Turn it off only when troubleshooting geometry issues, to rule out the solver.

Reuse fisheye features

Default: OFF. Reuses the features already found on the fisheye images (Stage 1) for the pinhole views, instead of detecting new features from scratch on the tiles. Skipping tile feature detection makes the pinhole stage faster — how much faster depends on the clip — and uses much less VRAM.

Trade-off: fine details come out slightly softer, and some can be missing.

It can also change the alignment, because the two paths use different feature caps. Reusing fisheye features draws on the larger fisheye SIFT extraction max of 32,768 features, while detecting fresh on the pinhole tiles is capped at 8,192. Both caps can be changed in the advanced settings.

	Reuse ON	Reuse OFF
Pinhole stage speed	Faster (varies by clip)	Baseline
Point cloud	Fewer points; fine detail slightly softer	Denser, crisper fine detail
GPU VRAM	~1 GB	~4–8 GB
SIFT extraction max	32,768 (fisheye)	8,192 (pinhole tiles)

Ignored for flat (non-360) input.

Geometry timeline check (experimental)

Fixes "impossible" folded geometry: when two places in your scene look identical (the same wallpaper in two hotel rooms, a stairwell walked up and then down, mirrored floor layouts), the matcher can merge them into one and the model folds onto itself.

The check enforces a simple rule: frames far apart in time must also be far apart in space — otherwise the camera would have to teleport. When a fold is detected, it retries alignment with progressively tighter temporal limits until the fold is gone, and uses GPS (when available) to make sure real loop closures are kept.

Turn it on for interiors with repeating patterns, identical facades or stairwell walks. It only acts if a fold is actually detected.

Result message	Meaning
Clean	No fold detected — nothing was changed.
Fold detected → cleared at gate W=X	The fold was found and fixed automatically.
Fold detected → no gate worked	Couldn't fix automatically — mask the duplicated content, split the clip into sections, or trim the problem part.

Feature quality preset

Controls how aggressively Stage 2 extracts and matches features:

Preset	Best for	Speed (8K)	Point density	GPU VRAM
Low	Low-VRAM cards (~4 GB)	~2–5 min	Sparse	Minimal
Default	Most users	~5–10 min	Moderate	Standard
High	Maximum detail	~15–30 min	Dense	~8+ GB

Start with Default. Switch to Low if the GPU runs out of memory during Stage 2, or to High when walls look too sparse after training and you have the VRAM and time — it extracts roughly 30–50% more features. Tweaking any individual setting switches the preset to Custom, which you can save under its own name.

Detail photos

Register extra stills (phone, DSLR, drone) into a finished 360 alignment. The stills are posed inside the existing model — the video geometry stays frozen — giving you high-resolution detail in areas the 360 video only covers coarsely.

1. Before running the pipeline, click "Add detail photos…" on the Alignment tab and pick a folder of stills.
2. Use one subfolder per camera (COLMAP shares lens parameters per folder — don't zoom mid-set or mix cameras in one folder). Loose images are treated as a single camera.
3. Run the pipeline as normal — the stills are aligned together with the video.

Supported formats: .jpg, .png, .tif. HEIC and RAW are not — export to JPG (quality 90–95 is fine) first.

For good registration, shoot the stills during the same visit and from positions on or near the camera path — stills with no visual overlap with the video (or with each other) will fail to register.