InstantSplat: Unbounded Sparse-view Pose-free Gaussian Splatting in 40
  Seconds
Authors: name: Zhiwen Fan; name: Wenyan Cong; name: Kairun Wen; name: Kevin Wang; name: Jian Zhang; name: Xinghao Ding; name: Danfei Xu; name: Boris Ivanovic; name: Marco Pavone; name: Georgios Pavlakos; name: Zhangyang Wang; name: Yue Wang
Published: 2024-03-29 17:29:58

Abstract: While novel view synthesis (NVS) has made substantial progress in 3D computer
vision, it typically requires an initial estimation of camera intrinsics and
extrinsics from dense viewpoints. This pre-processing is usually conducted via
a Structure-from-Motion (SfM) pipeline, a procedure that can be slow and
unreliable, particularly in sparse-view scenarios with insufficient matched
features for accurate reconstruction. In this work, we integrate the strengths
of point-based representations (e.g., 3D Gaussian Splatting, 3D-GS) with
end-to-end dense stereo models (DUSt3R) to tackle the complex yet unresolved
issues in NVS under unconstrained settings, which encompasses pose-free and
sparse view challenges. Our framework, InstantSplat, unifies dense stereo
priors with 3D-GS to build 3D Gaussians of large-scale scenes from sparseview &
pose-free images in less than 1 minute. Specifically, InstantSplat comprises a
Coarse Geometric Initialization (CGI) module that swiftly establishes a
preliminary scene structure and camera parameters across all training views,
utilizing globally-aligned 3D point maps derived from a pre-trained dense
stereo pipeline. This is followed by the Fast 3D-Gaussian Optimization (F-3DGO)
module, which jointly optimizes the 3D Gaussian attributes and the initialized
poses with pose regularization. Experiments conducted on the large-scale
outdoor Tanks & Temples datasets demonstrate that InstantSplat significantly
improves SSIM (by 32%) while concurrently reducing Absolute Trajectory Error
(ATE) by 80%. These establish InstantSplat as a viable solution for scenarios
involving posefree and sparse-view conditions. Project page:
instantsplat.github.io.