论文标题

基于CNN的近场光度立体声问题的方法

A CNN Based Approach for the Near-Field Photometric Stereo Problem

论文作者

Logothetis, Fotios, Budvytis, Ignas, Mecca, Roberto, Cipolla, Roberto

论文摘要

在不同的光源下,使用几个图像重建对象的3D形状是一项非常具有挑战性的任务,尤其是当考虑到诸如光传播和衰减之类的现实假设时,考虑了观察几何形状和镜面反射。许多解决光度立体声(PS)问题的作品通常会放松上述大部分假设。特别是他们忽略了镜面反射和全球照明效应。在这项工作中,我们提出了第一种基于CNN的方法,能够在光度立体声中处理这些现实的假设。我们利用深度神经网络的最新改进用于远场光度立体声,并使其适应近场设置。我们通过采用迭代程序进行形状估计来实现这一目标,该过程具有两个主要步骤。首先,我们训练每像素CNN,从反射样品中预测表面垂直。其次,我们通过整合正常场来计算深度,以迭代估算光方向和衰减,该方向和衰减用于补偿输入图像以计算下一次迭代的反射样品。据我们所知,这是第一个近场框架,能够从高度镜面对象准确预测3D形状。我们的方法优于在合成和真实实验方面竞争的最新近场光度立体观点方法。

Reconstructing the 3D shape of an object using several images under different light sources is a very challenging task, especially when realistic assumptions such as light propagation and attenuation, perspective viewing geometry and specular light reflection are considered. Many of works tackling Photometric Stereo (PS) problems often relax most of the aforementioned assumptions. Especially they ignore specular reflection and global illumination effects. In this work, we propose the first CNN based approach capable of handling these realistic assumptions in Photometric Stereo. We leverage recent improvements of deep neural networks for far-field Photometric Stereo and adapt them to near field setup. We achieve this by employing an iterative procedure for shape estimation which has two main steps. Firstly we train a per-pixel CNN to predict surface normals from reflectance samples. Secondly, we compute the depth by integrating the normal field in order to iteratively estimate light directions and attenuation which is used to compensate the input images to compute reflectance samples for the next iteration. To the best of our knowledge this is the first near-field framework which is able to accurately predict 3D shape from highly specular objects. Our method outperforms competing state-of-the-art near-field Photometric Stereo approaches on both synthetic and real experiments.

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