SplatfastK1

Turn a phone video into a 3D Gaussian splat — without a GPU, without the command line.

SplatfastK1 is a free, open-source Windows desktop app that takes a normal phone video and produces a Blender-ready Gaussian splat scene. It does the heavy training on a cloud GPU (your own Replicate account) so you don't need an NVIDIA card on your laptop, and it opens the result in Blender at the exact angle the first video frame was shot from.

No telemetry. No SaaS lock-in. Your videos and trained splats stay on your machine. The only cloud component is the GPU training step, which runs in your own Replicate account using a token you paste once.

What it does, in one picture

   phone video                 cloud GPU (your account)
       |                              ^
       v                              |
   [ Extract frames ] --> [ COLMAP SfM ] --> [ Upload zip ]
                                                  |
                                                  v
                                          [ Brush trains splat ]
                                                  |
                                                  v
   [ Blender opens at first-frame camera pose ] <- [ Download .ply ]

Why it's different

	SplatfastK1	Polycam / Luma	PostShot	SkySplat
Standalone desktop app	✅	❌ (mobile/web)	✅	❌ (Blender addon)
Works without a GPU	✅ (cloud)	✅ (their cloud)	❌	❌
Your own cloud account, not a SaaS	✅	❌	n/a	n/a
Auto-opens in Blender	✅	❌	❌	✅
Opens at original camera angle	✅	❌	❌	✅
Free & open source	✅	❌	✅ (closed)	✅
Non-technical UX (no CLI)	✅	✅	✅	❌

We don't compete on the splat algorithm — we use Brush under the hood. We compete on the end-to-end UX: a non-technical person with a phone and a $5 Replicate credit can produce a real Gaussian splat in Blender in about 5 minutes.

Quick start

1. Install Python 3.11+ from python.org (check "Add Python to PATH" when installing).
2. Clone the repo:

   git clone https://github.com/Kmollo/splatfastk1.git
   cd splatfastk1

3. Double-click Start_SplatfastK1.bat in the folder. That's it.

The launcher will:

• Install Python dependencies automatically (one-time, ~30 sec)
• Add SplatfastK1 to your Start Menu + Desktop (so you can find it via Windows search next time)
• Open the app, which shows a Setup screen on first launch — click Install everything I can and it downloads Brush, BlendSplat, and COLMAP for you

After Setup completes, you'll only need to install Blender 5.1 (download) and grab a free Replicate API key (signup) for cloud training. See REQUIREMENTS.md for the full list.

⚠️ First-launch SmartScreen warning

The very first time you double-click Start_SplatfastK1.bat, Windows Defender SmartScreen will probably pop up a blue warning:

"Windows protected your PC — Microsoft Defender SmartScreen prevented an unrecognized app from starting."

This is standard for any script downloaded from the internet — even from big legitimate projects. It just means we haven't paid Microsoft for a code- signing certificate (which costs ~$200/year). The app itself is fine; you can read every line of source code in this repo.

To proceed: click "More info", then "Run anyway". Windows remembers your decision — you won't be prompted again.

Once you've launched the app

In Settings, paste your Replicate API token (free signup at replicate.com, pay-as-you-go ~$0.03 per fast train, ~$0.20 per high-quality train).

Then click Start Project, drop a video, name it, hit Train. When it's done, click Open in Blender.

Alternative: launch from the command line

If you prefer the terminal:

python -m desktop.main

4. In Settings, paste your Replicate API token (free signup at replicate.com, pay-as-you-go ~$0.03 per fast train, ~$0.20 per high-quality train).
5. Click Start Project, drop a video, name it, hit Train.
6. When it's done, click Open in Blender.

How to capture a good video

• Walk around the subject, not toward it (orbit, don't dolly).
• Keep the subject in frame, well-lit, no motion blur.
• 30-90 seconds at 30 fps is plenty.
• Avoid: flat textureless walls, mirrors, fast-moving subjects, transparent glass, rotating turntables (the camera needs to move, not the object).

Features

• Drag-and-drop UI built in PyQt6 — no terminal required
• Local prep + cloud train — frame extraction + COLMAP run on your machine; only the small COLMAP dataset gets uploaded for training (your original video never leaves your computer)
• Live progress — streaming logs from the cloud GPU, with parsed step counters so you actually know how far in you are
• Project library — saved projects appear in the Projects tab, click to re-open at the Done page with all action buttons (View Splat / Blender / Show Files / Train Again)
• Resume training — train the same project again at a different quality setting without re-doing COLMAP
• Smart Blender import — auto-detects BlendSplat or Kiri 3DGS Render and builds the right shader chain; reads the COLMAP camera poses to place Blender's camera at the original first-frame angle
• Secure secret storage — API key lives in Windows Credential Manager, never in plaintext on disk
• Local-only mode — if you have an NVIDIA GPU, you can skip the cloud step entirely (toggle on the project setup page)

CLI (optional)

The desktop app is the primary interface, but there's also a real CLI:

splatforge doctor                                # check what's installed
splatforge create input.mp4 --quality fast       # run the full pipeline
splatforge create input.mp4 --backend none       # local prep only, no training

Project structure

A completed project at ~/SplatfastK1/outputs/<name>/:

<name>/
  images/              <- extracted frames
  reconstruction/      <- COLMAP sparse model
  splat/scene.ply      <- the trained Gaussian splat
  blender/             <- placeholder for Blender outputs
  logs/                <- pipeline logs
  splatforge.json      <- project manifest

Architecture

desktop/         PyQt6 GUI — the app a user opens
src/splatforge/  Pipeline core: CLI, FFmpeg + COLMAP orchestration, project layout
replicate_model/ The Cog/Replicate model code that trains Brush in the cloud
blender_addon/   Optional Blender addon for importing a project folder
docs/            Architecture notes and design decisions

See docs/ARCHITECTURE.md for the deeper tour.

Security

• No telemetry, no analytics, no third-party SDKs
• API key stored in Windows Credential Manager (same vault Edge uses)
• All network calls are HTTPS, scoped to api.replicate.com and *.replicate.delivery
• Full threat model + defenses are in SECURITY.md

Status

Working end-to-end on Windows 10/11. Mac and Linux support is feasible but not in this release — the cloud pipeline is cross-platform, but the Blender launcher and Start Menu integration are Windows-only.

Contributing

See CONTRIBUTING.md. Run the smoke test before submitting a PR:

python -m desktop.test_buttons    # 46 button-wiring checks
python -m pytest                  # CLI/pipeline tests

Credits

• Gaussian splat training: Brush by Arthur Brussee
• Splat rendering in Blender: BlendSplat by soerensc
• Photogrammetry: COLMAP
• Cloud GPU runtime: Replicate + cog

License

MIT — see LICENSE.