Resolution Where It Counts:
Hash-based GPU-Accelerated 3D Reconstruction
via Variance-Adaptive Voxel Grids
ACM Transaction on Graphics

  • Sapienza, University of Rome    

MrHash is a GPU-accelerated 3D reconstruction pipeline that uses variance-adaptive voxel hashing
for efficient TSDF fusion with optional 3D Gaussian Splatting rendering.

Overall comparison

Use the slider to switch between meshes and 3DGS renderings

Abstract

Efficient and scalable 3D surface reconstruction from range data remains a core challenge in computer graphics and vision, particularly in real-time and resource-constrained scenarios. Traditional volumetric methods based on fixed-resolution voxel grids or hierarchical structures like octrees often suffer from memory inefficiency, computational overhead, and a lack of GPU support. We propose a novel variance-adaptive, multi-resolution voxel grid that dynamically adjusts voxel size based on the local variance of signed distance field (SDF) observations. Unlike prior multi-resolution approaches that rely on recursive octree structures, our method leverages a flat spatial hash table to store all voxel blocks, supporting constant-time access and full GPU parallelism. This design enables high memory efficiency, and real-time scalability. We further demonstrate how our representation supports GPU-accelerated rendering through a parallel quad-tree structure for Gaussian Splatting, enabling effective control over splat density. Our open-source CUDA/C++ implementation achieves up to 13× speedup and 4× lower memory usage compared to fixed-resolution baselines, while maintaining on par results in terms of reconstruction accuracy, offering a practical and extensible solution for high-performance 3D reconstruction.

Resolution Comparisons

Same scene, three variance thresholds (σ). Hover or drag each slider to compare the mesh with the underlying fine and coarse voxels.

σ = 0.001

σ = 0.001
Baseline figure
Mesh σ = 0.001

σ = 0.005

σ = 0.005
Baseline figure
Mesh σ = 0.005

σ = 0.01

σ = 0.01
Baseline figure
Mesh σ = 0.01

3D Reconstruction - Newer College

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Runtimes Comparison

Runtimes per frame (ms) and FPS. Best results are highlighted as first and second. Dash indicates missing values due to failures.

Method ScanNet Replica Oxford-Spires Newer College
Time [ms]↓ FPS↑ Time [ms]↓ FPS↑ Time [ms]↓ FPS↑ Time [ms]↓ FPS↑
VDBFusion 17.45 5.71 519 1.93 40.31 24.65 103.62 9.61
PIN-SLAM 67.15 14.80 68 14.7 75.99 13.15 113.68 8.79
N3Mapping 184.67 5.40 255.44 3.91
NKSR 16.05 62.28
Voxblox 132.06 7.57 373 2.68 61.72 16.17 162.47 6.14
Supereight2† 73.94 13.53 100.87 9.92
Supereight2‡ 79.52 12.55 98.11 10.20
Ours (single) 15.11 64.30 20.45 48.9 14.27 68.86 30.18 21.6
Ours (multi) 16.79 59.34 37.50 26 16.39 61 28.17 35.25

Supereight2† uses a single-resolution grid, Supereight2‡ a multi-resolution grid. Our single-resolution variant is 2×–13× faster than prior work across datasets.

3D Reconstruction Results

All pipelines run with ground-truth poses on ScanNet (RGB-D) and Newer College (LiDAR) sequences (voxel size 1 cm and 20 cm respectively, F-score thresholds of 10 cm and 20 cm). Best results are highlighted as first and second.

Method Metric RGB-D LiDAR Average
0000 0010 0059 0106 0109 0181 0207 quad math cloi RGB-D LiDAR Overall
PIN-SLAM Acc. [cm]↓ 2.680 4.069 5.789 6.540 2.802 4.161 4.004 9.942 10.271 9.082 4.292 9.765 5.934
Comp. [cm]↓ 1.078 1.060 1.464 1.732 0.862 1.648 1.085 13.764 13.960 14.584 1.276 14.103 5.124
C-L1↓ 1.879 2.565 3.626 4.136 1.832 2.905 2.544 11.853 12.116 11.833 2.784 11.934 5.529
F-score [%]↑ 97.966 94.486 87.775 83.363 96.209 93.494 93.496 83.724 83.596 82.431 92.398 83.250 89.654
VDBFusion Acc. [cm]↓ 2.217 2.473 4.615 5.472 1.603 4.090 2.874 6.511 8.669 6.511 3.336 7.230 4.504
Comp. [cm]↓ 0.925 0.707 1.122 0.885 0.516 0.928 0.779 11.645 12.684 12.657 0.837 12.329 4.285
C-L1↓ 1.571 1.590 2.869 3.179 1.059 2.509 1.826 9.078 10.677 9.584 2.086 9.780 4.394
F-score [%]↑ 97.052 95.687 88.896 85.161 97.659 89.723 94.692 89.532 87.157 87.963 92.696 88.217 91.352
Voxblox Acc. [cm]↓ 2.120 2.718 4.156 4.137 2.583 4.246 2.678 9.824 8.619 9.284 3.234 9.242 5.037
Comp. [cm]↓ 1.759 6.168 2.145 2.304 9.045 2.638 3.817 17.083 14.756 26.207 3.982 19.349 8.592
C-L1↓ 1.939 4.443 3.150 3.220 5.814 3.442 3.247 13.453 11.688 17.746 3.608 14.296 6.814
F-score [%]↑ 96.076 89.194 89.313 88.593 84.653 91.204 91.329 79.400 83.699 63.518 90.052 75.539 85.698
Supereight2† Acc. [cm]↓ 2.151 2.364 5.354 4.781 2.064 4.221 3.151 fail fail fail 3.441
Comp. [cm]↓ 1.457 1.294 2.002 1.484 1.183 1.983 1.470 fail fail fail 1.553
C-L1↓ 1.804 1.829 3.678 3.132 1.623 3.102 2.310 fail fail fail 2.497
F-score [%]↑ 97.478 97.399 87.040 88.131 97.073 91.905 95.252 fail fail fail 93.468
Supereight2‡ Acc. [cm]↓ 1.955 2.364 5.250 4.176 2.064 3.834 3.096 fail fail fail 3.248
Comp. [cm]↓ 1.452 1.296 2.011 1.464 1.182 1.954 1.476 fail fail fail 1.548
C-L1↓ 1.704 1.830 3.631 2.820 1.623 2.894 2.286 fail fail fail 2.398
F-score [%]↑ 98.168 97.394 87.454 90.752 97.075 93.458 95.445 fail fail fail 94.250
N3Mapping Acc. [cm]↓ fail 1.705 2.338 3.374 1.706 2.134 1.786 fail fail fail 2.174
Comp. [cm]↓ fail 1.335 1.664 1.390 1.133 2.616 1.222 fail fail fail 1.560
C-L1↓ fail 1.520 2.001 2.382 1.420 2.375 1.504 fail fail fail 1.867
F-score [%]↑ fail 98.811 96.398 93.671 98.076 97.034 97.293 fail fail fail 96.880
Ours Acc. [cm]↓ 0.963 1.587 2.981 2.822 1.364 2.789 1.701 7.134 9.061 7.015 2.030 7.737 3.742
Comp. [cm]↓ 1.053 1.079 1.414 1.202 0.961 1.968 1.234 11.898 13.116 14.208 1.273 13.074 4.813
C-L1↓ 1.008 1.333 2.198 2.012 1.162 2.379 1.366 9.516 11.088 10.612 1.637 10.405 4.267
F-score [%]↑ 99.674 98.408 94.124 94.200 98.079 96.183 97.246 89.503 85.811 84.815 96.845 86.710 93.804

Supereight2† uses a single-resolution grid, Supereight2‡ a multi-resolution grid. Both Supereight2 variants and N3Mapping fail on all LiDAR sequences; averages in red are computed only where reconstructions succeed.

Citation

If you want to cite our work, please use:

@article{10.1145/3777909,
author = {De Rebotti, Lorenzo and Giacomini, Emanuele and Grisetti, Giorgio and Di Giammarino, Luca},
title = {Resolution Where It Counts: Hash-based GPU-Accelerated 3D Reconstruction via Variance-Adaptive Voxel Grids},
year = {2025},
publisher = {Association for Computing Machinery},
address = {New York, NY, USA},
issn = {0730-0301},
url = {https://doi.org/10.1145/3777909},
doi = {10.1145/3777909},
journal = {ACM Trans. Graph.},
keywords = {Surface Reconstruction, Novel View Synthesis, Gaussian Splatting}}
                    

Acknowledgements

The website template was borrowed from Michaël Gharbi and MipNeRF360.