3dgsconverter

3D Gaussian Splatting Converter

A versatile, high-performance tool for converting between various 3D Gaussian Splatting formats. It supports advanced filtering, GPU acceleration, and universal N-to-N conversion between all supported formats.

Key Features

• Universal Conversion: Convert any supported format to any other format (e.g., .ply to .ksplat, .spz to .ply, .sog to .sog).
• Cross-Platform: Fully compatible with Windows, Linux, and macOS (Apple Silicon & Intel).
• GPU Acceleration: Built-in GPU support via Taichi Lang for extremely fast K-Means clustering (SOG/KSplat compression) and Statistical Outlier Removal (SOR). Supports NVIDIA CUDA, Apple Metal, and Vulkan/Integrated GPUs.
• Advanced Filtering:
  • Region of Interest: Crop using Manual Bounding Box (Runs first for speed).
  • Alpha/Opacity: Remove transparent splats.
  • Density Control: Remove sparse areas while keeping dense clusters (Multi-cluster support).
  • Outlier Removal: Statistical Outlier Removal (SOR) to clean up “flyers”.
• Compression Control: Balance quality and file size with --compression_level (0 = Max Quality).
• Format Agnostic: Filters apply to the intermediate raw data, so they work on ANY input format.
• Custom Data Preservation: Use --extra_elements to maintain non-standard PLY properties (like camera parameters) when converting between PLY formats.

Supported Formats & Peculiarities

Installation

It is recommended to use Conda to manage dependencies.

1. Create and Activate Conda Environment:

   conda create -n gsconv python=3.10
   conda activate gsconv
   

   (Or use a local .venv if preferred)

2. Install the Package:

   Option A: Quick Install (via pip)

   pip install git+https://github.com/francescofugazzi/3dgsconverter.git
   

   Option B: Manual Development Install (Clone)

   git clone https://github.com/francescofugazzi/3dgsconverter.git
   cd 3dgsconverter
   pip install -r requirements.txt
   

   Note: To enable GPU acceleration, ensure taichi is installed (pip install taichi). It is included in requirements.txt.

Usage

Basic syntax:

3dgsconverter -i <input_file> -f <target_format> [-o <output_file>] [options]

(Aliases: gsconverter, 3dgsconv, gsconv) Note: -o is optional. If omitted, the output filename is derived from the input with the correct extension. Use --force to overwrite existing files without confirmation.

Common Examples

1. Basic Conversion (PLY to KSplat)

3dgsconverter -i input.ply -f ksplat
# Creates input.ksplat automatically

2. High-Quality Compression (SOG)

# Level 1 = High Quality. Level 10 = High Compression.
3dgsconverter -i input.ply -o output.sog -f sog --compression_level 1

3. Cleaning a Point Cloud (Filters)

# Remove invisible points and outliers
3dgsconverter -i raw.ply -o clean.ply -f 3dgs --min_opacity 5 --sor_intensity 8

4. Extracting a Region of Interest

# Crop BEFORE filtering (Attributes: minX minY minZ maxX maxY maxZ)
3dgsconverter -i scene.spz -o crop.ply -f 3dgs --bbox -2 -2 -2 2 2 2

Parameter Reference

General

• -i, --input: Path to source file.
• -o, --output: Path to destination file (Optional).
• -f, --format: Target format (3dgs, cc, ksplat, splat, sog, spz, parquet, compressed_ply).
• --force: Overwrite existing output file without prompting.
• --rgb: Force RGB generation from SH (for supported formats).
• --extra_elements: Preserves non-standard PLY elements (like extrinsic, intrinsic) when converting between 3DGS/CC formats.
• --sh_level: Target SH degree (0-4). Tool never upscales; keeps source degree if lower.
• --crop_sh: Trims SH padding and only writes the coefficients actually present in the source. Useful when you want a tighter, non-canonical output.
• --preserve_sh4: Experimental opt-in. Preserve SH4 on compatible non-SPZ-v4 formats when the source already contains SH4. Standard writes remain capped at SH3.
• --spz_version: SPZ output version. Default 3; use 4 for the new plaintext-header format and native SH4 support.
• --compression_level: 0-10. Controls quality/size ratio for supported formats (SOG, KSplat, SPZ v3/v4).
  • KSplat: Set to 2 for quantization (experimental levels >2 map to 2).

Advanced Filters

Filters run in this specific order for efficiency:

1. Manual BBox (--bbox): Crops space first.
2. Alpha Filter (--min_opacity <0-255>): Discards points with opacity < threshold.
3. Density Filter:
   • --density_sensitivity <0.0-1.0>: Simple slider. 0.0 = Lazy (keeps more), 1.0 = Aggressive (removes sparse halos).
   • --keep_multicluster: If set, keeps all dense clusters. Default: keeps only the largest main cluster.
4. SOR (Flyers):
   • --sor_intensity <1-10>: Simple slider. 1 = Weak (keeps more), 10 = Strong (removes all outliers).
5. Auto BBox (--auto_bbox):
   • Calculates the minimal bounding box of the remaining valid points before saving, ensuring tight packing.

Technical Details

Built with Taichi Lang for high-performance GPU computing.

• Parallelism: Voxels and SOR are processed in parallel on the GPU.
• Differentiable Design: While currently used for conversion, the core is differentiable, allowing for future optimization and training applications.
• No Upscale Rule: The converter never invents higher SH detail than the source contains. Standard exports remain capped at SH3 by default; use --preserve_sh4 to keep SH4 only on compatible formats, and spz_version=4 for native SPZ SH4 output.

Credits

This project builds upon the incredible work of the 3D Gaussian Splatting community. Special thanks to:

• Inria (GraphDeco): The original 3D Gaussian Splatting paper and implementation.
• Antimatter15: For the .splat format and the first WebGL viewer.
• mkkellogg: For the .ksplat format and 3DGS-Three.js integration.
• Niantic Labs: For the .spz format definition.
• PlayCanvas: For the .sog format, .ply chunk-quantization schema, and SuperSplat viewer.

Refactoring & Breaking Changes (Type-Check Safe)

This project has undergone a complete refactoring to modularize the codebase and improve type safety. As a result, some legacy command-line arguments have been deprecated and replaced with more explicit or user-friendly alternatives.

Replaced Commands

New Features

• Format-Specific Compression: The --compression_level flag adapts to the target format:

  • KSplat:
    • 0: No compression (Float32 w/ SH). Max quality.
    • 1: Block compression (Uint16 Pos, Float16 Scale/Rot/SH). Good balance.
    • 2+: Aggressive Block compression (Uint16 Pos, Float16 Scale/Rot, Uint8 SH). Smallest size, lossy SH.
  • SPZ: Controls compression effort. spz_version=3 uses Gzip; spz_version=4 uses ZSTD. This is lossless for the data itself, affecting only file size and save time.

• SH4 Output Policy: Standard exports stay at SH3 by default. Use --preserve_sh4 for experimental SH4 preservation on compatible formats (3dgs, cc, compressed_ply, parquet, sog) when the source already contains SH4. Older viewers may not support SH4. SPZ v4 is the separate native SH4 path.

  • SOG: Controls SH Palette Quality (0=Max Quality, 9=Min Quality). Note: Texture compression is always Lossless WebP.

• User-Friendly Sliders: New --density_sensitivity (0.0-1.0) and --sor_intensity (1.0-10.0) abstract complex parameters away for easier use.

• Modular Architecture: The monolith code has been split into formats/, processing/, and utils/ for better maintainability and extensibility.