# Randomly distributed optical fibers in translucent mortar for privacy-preserving light transmission and digital image reconstruction

## TL;DR

This paper introduces a new type of building material that hides visual information physically but allows it to be digitally reconstructed, offering privacy and smart infrastructure potential.

## Contribution

A novel composite material with randomly distributed optical fibers and a computational system for privacy-preserving light transmission and image recovery.

## Key findings

- The random fiber distribution effectively diffuses light to preserve physical privacy.
- Digital imaging and calibration accurately reconstruct hidden visual information.
- The material maintains performance across various viewing distances and angles with minimal error.

## Abstract

Light-transmitting building materials often compromise visual privacy due to coherent light transmission. This study presents a novel composite utilizing randomly distributed optical fibers coupled with a computational image reconstruction system. A limestone-calcined clay cement (LC³) inspired matrix was designed for sustainability and material performance. An algorithmic approach assigned a random traceable fiber distribution via a bijective input-output mapping. The random fiber configuration achieves effective light diffusion, preserving physical privacy. However, using digital imaging and homography-based calibration, the network was computationally reconstructed to reverse the diffusion, recovering hidden visual information accurately. This demonstrates a dual functionality: architectural privacy combined with selective digital transparency. Geometric robustness tests confirmed a stable operational envelope (estimated error of 2.9%) across viewing distances of 30–110 cm and camera rotation angles up to ± 35º (pitch and yaw), establishing these fiber-instrumented cementitious composites as hybrid physical-digital materials for smart infrastructure applications.

The online version contains supplementary material available at 10.1038/s41598-025-32224-2.