> For the complete documentation index, see [llms.txt](https://multiset.gitbook.io/multiset/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://multiset.gitbook.io/multiset/basics/maps/output-asset/gaussian-splat.md).

# Gaussian Splat

## Overview

A Gaussian Splat is the photoreal representation of a mapped space. Where the mesh gives you geometry you can collide with, the splat gives you appearance: view-dependent detail, thin structures, and reflective surfaces that a mesh cannot hold. It is what the **View Splat** viewer in the Developer Portal renders.

## Two formats

| Format         | Extension | Notes                                                                                                                                                 |
| -------------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Raw**        | `.ply`    | Full precision, uncompressed, the largest file. Opens in standard Gaussian Splat tooling.                                                             |
| **Compressed** | `.spz`    | Compact form of the same splat, typically around a tenth of the `.ply` size. Use it for web and mobile viewers where download size and memory matter. |

Both files describe the same reconstruction. Pick `.ply` when you are editing or re-processing the splat, and `.spz` when you are streaming it to a client.

## Which maps have a splat

Gaussian Splats are produced for two inputs:

* [**360 video**](/multiset/basics/third-party-scans/360-videos/insta360-scans.md) captures (Insta360 `.insv`), where the splat is generated as part of reconstruction along with the panoramas and the mesh.
* [**Gaussian Splat uploads**](/multiset/basics/third-party-scans/gaussian-splat.md) (`.ply` plus `poses.json`), where MultiSet reconstructs a mesh from your splat and returns the splat itself, re-aligned.

Maps built from `.e57` or MatterPak scans produce a [mesh](/multiset/basics/maps/output-asset/mesh.md) and [panoramas](/multiset/basics/maps/output-asset/360-virtual-tour.md), but no splat. LiDAR captures from the MultiSet App and Unity SDK produce a mesh only. See [Output Asset](/multiset/basics/maps/output-asset.md) for the full input-to-asset matrix.

## Coordinate alignment

The splat you download is **not** the file you uploaded. Its coordinates are modified so that the splat shares the map's frame: origin at `(0, 0, 0)`, `+Y` up, metric scale, sitting exactly on the generated mesh.

{% hint style="warning" %}
Always render the splat returned by MultiSet, not your original upload. The original sits in your reconstruction tool's arbitrary frame, so content placed with VPS poses will not line up with it.
{% endhint %}

Because the splat, the mesh, and the VPS poses share one frame, you can author against the mesh and render the splat, or the other way round, and everything stays registered. See [Coordinate Systems](/multiset/basics/localization/coordinate-systems.md).

## Viewing and scaling

Open the map from the **Maps** list, then click **View Splat** in the Map Details toolbar:

<figure><img src="/files/LBwZyUnecUGdYqjeDW8E" alt="Map Details toolbar with the View Splat button"><figcaption><p>Map Details toolbar. Open <strong>View Splat</strong>.</p></figcaption></figure>

For a 360 video capture recorded without a calibration marker, the **Scaling** tool inside the splat viewer sets the map's real-world scale: measure something of a known length, enter that length in metres, and confirm. The scale factor applies to the map as a whole, so the mesh and stored metrics move with it. See [Map Scale](/multiset/basics/rest-api-docs/map-scale.md).


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