Accurate Point Measurement in 3DGS -- A New Alternative to Traditional Stereoscopic-View Based Measurements

Abstract

3D Gaussian Splatting (3DGS) has revolutionized real-time rendering with its state-of-the-art novel view synthesis, but its utility for accurate geometric measurement remains underutilized. Compared to multi-view stereo (MVS) point clouds or meshes, 3DGS rendered views present superior visual quality and completeness. However, current point measurement methods still rely on demanding stereoscopic workstations or direct picking on often-incomplete and inaccurate 3D meshes. As a novel view synthesizer, 3DGS renders exact source views and smoothly interpolates in-between views. This allows users to intuitively pick congruent points across different views while operating 3DGS models. By triangulating these congruent points, one can precisely generate 3D point measurements. This approach mimics traditional stereoscopic measurement but is significantly less demanding: it requires neither a stereo workstation nor specialized operator stereoscopic capability. Furthermore, it enables multi-view intersection (more than two views) for higher measurement accuracy. We implemented a web-based application to demonstrate this proof-of-concept (PoC). Using several UAV aerial datasets, we show this PoC allows users to successfully perform highly accurate point measurements, achieving accuracy matching or exceeding traditional stereoscopic methods on standard hardware. Specifically, our approach significantly outperforms direct mesh-based measurements. Quantitatively, our method achieves RMSEs in the 1-2 cm range on well-defined points. More critically, on challenging thin structures where mesh-based RMSE was 0.062 m, our method achieved 0.037 m. On sharp corners poorly reconstructed in the mesh, our method successfully measured all points with a 0.013 m RMSE, whereas the mesh method failed entirely. Code is available at: https://github.com/GDAOSU/3dgs_measurement_tool.

Figures (6)

• Figure 1: User interface of the web-based measurement application. The panel (left) lists the computed 3D points and their corresponding RMS error ($\sigma$). In the 3D view, multiple user-aimed rays (yellow lines) are used to compute the 3D point via spatial intersection. The final point is visualized as a 3D error ellipsoid (blue/green), providing immediate feedback on the measurement's precision.
• Figure 2: Datasets used for experiments. (a - c): mesh models for Dataset 1 - 3; (d - f): 3DGS models for Datasets 1 - 3.
• Figure 3: Ground truth generation in iTwin Capture Modeler Bentley2024. A single validation point (VP) is precisely measured across multiple source images. The system then computes its 3D coordinate via rigorous spatial intersection, which serves as the high-accuracy ground truth for our validation.
• Figure 4: Distribution of the 20 validation points (VPs) used for the accuracy assessment, shown on the 3DGS rendering of the three datasets. (Top Left) Dataset 1: steel sculpture; (Bottom Left) Dataset 2: wood sculpture. (Right) Dataset3: campus building.
• Figure 5: Visual analysis of measurement feasibility on thin structures (Dataset 1). This table compares measurement attempts on five different thin, pole-like features. The Mesh detail column (Col. 2) shows the mesh geometry, which appears missing or discontinuous for points 4 and 5 (circled in yellow), leading to measurement failure. The 3DGS detail column (Col. 3) shows the visually coherent 3DGS rendering, which enabled successful and precise measurements (indicated by the blue error ellipsoid) for all five points.