Coordinate Quantized Neural Implicit Representations for Multi-view Reconstruction

TL;DR

This paper introduces a novel approach for 3D reconstruction using neural implicit representations with quantized coordinates, which stabilizes training and improves multi-view consistency without additional computational costs.

Contribution

The authors propose discretizing coordinates into quantized values to enhance neural implicit 3D reconstruction stability and accuracy, outperforming state-of-the-art methods.

Findings

Reduces noise and artifacts in reconstructions.

Improves multi-view consistency in 3D inference.

Achieves superior results on benchmark datasets.

Abstract

In recent years, huge progress has been made on learning neural implicit representations from multi-view images for 3D reconstruction. As an additional input complementing coordinates, using sinusoidal functions as positional encodings plays a key role in revealing high frequency details with coordinate-based neural networks. However, high frequency positional encodings make the optimization unstable, which results in noisy reconstructions and artifacts in empty space. To resolve this issue in a general sense, we introduce to learn neural implicit representations with quantized coordinates, which reduces the uncertainty and ambiguity in the field during optimization. Instead of continuous coordinates, we discretize continuous coordinates into discrete coordinates using nearest interpolation among quantized coordinates which are obtained by discretizing the field in an extremely high resolution. We use discrete coordinates and their positional encodings to learn implicit functions through volume rendering. This significantly reduces the variations in the sample space, and triggers more multi-view consistency constraints on intersections of rays from different views, which enables to infer implicit function in a more effective way. Our quantized coordinates do not bring any computational burden, and can seamlessly work upon the latest methods. Our evaluations under the widely used benchmarks show our superiority over the state-of-the-art. Our code is available at https://github.com/MachinePerceptionLab/CQ-NIR.