FlashSplat: 2D to 3D Gaussian Splatting Segmentation Solved Optimally
Authors: name: Qiuhong Shen, name: Xingyi Yang, name: Xinchao Wang

This study addresses the challenge of accurately segmenting 3D Gaussian
Splatting from 2D masks. Conventional methods often rely on iterative gradient
descent to assign each Gaussian a unique label, leading to lengthy optimization
and sub-optimal solutions. Instead, we propose a straightforward yet globally
optimal solver for 3D-GS segmentation. The core insight of our method is that,
with a reconstructed 3D-GS scene, the rendering of the 2D masks is essentially
a linear function with respect to the labels of each Gaussian. As such, the
optimal label assignment can be solved via linear programming in closed form.
This solution capitalizes on the alpha blending characteristic of the splatting
process for single step optimization. By incorporating the background bias in
our objective function, our method shows superior robustness in 3D segmentation
against noises. Remarkably, our optimization completes within 30 seconds, about
50times faster than the best existing methods. Extensive experiments
demonstrate the efficiency and robustness of our method in segmenting various
scenes, and its superior performance in downstream tasks such as object removal
and inpainting. Demos and code will be available at
https://github.com/florinshen/FlashSplat.