A Reflectance Transformation Imaging technique (RTI) realized by multi-rotor Unmanned Aerial Vehicles (UAVs) with a focus on deployment in difficult to access buildings is presented in this letter. RTI is a computational photographic method that captures a surface shape and color of a subject and enables its interactive re-lighting from any direction in a software viewer, revealing details that are not visible with the naked eye. The input of RTI is a set of images captured by a static camera, each one under illumination from a different known direction. We present an innovative approach applying two multi-rotor UAVs to perform this scanning procedure in locations that are hardly accessible or even inaccessible for people. The proposed system is designed for its safe deployment within real-world scenarios in historical buildings with priceless historical value.

翻译：本文提出一种基于多旋翼无人飞行器（UAV）的反射变换成像（RTI）技术，重点面向难以进入的建筑结构部署。RTI是一种计算摄影方法，可捕捉目标的表面形状与色彩，并在软件查看器中实现任意方向的交互式重光照，揭示肉眼无法观察的细节。RTI的输入为由静态相机拍摄的一组图像，每幅图像在不同已知方向光照下采集。我们提出一项创新方法，利用两架多旋翼无人飞行器在人类难以或无法进入的场所执行该扫描流程。该系统专为具有无价历史价值的古建筑真实场景安全部署而设计。