Geometry reconstruction of textureless, non-Lambertian objects under unknown natural illumination (i.e., in the wild) remains challenging as correspondences cannot be established and the reflectance cannot be expressed in simple analytical forms. We derive a novel multi-view method, DeepShaRM, that achieves state-of-the-art accuracy on this challenging task. Unlike past methods that formulate this as inverse-rendering, i.e., estimation of reflectance, illumination, and geometry from images, our key idea is to realize that reflectance and illumination need not be disentangled and instead estimated as a compound reflectance map. We introduce a novel deep reflectance map estimation network that recovers the camera-view reflectance maps from the surface normals of the current geometry estimate and the input multi-view images. The network also explicitly estimates per-pixel confidence scores to handle global light transport effects. A deep shape-from-shading network then updates the geometry estimate expressed with a signed distance function using the recovered reflectance maps. By alternating between these two, and, most important, by bypassing the ill-posed problem of reflectance and illumination decomposition, the method accurately recovers object geometry in these challenging settings. Extensive experiments on both synthetic and real-world data clearly demonstrate its state-of-the-art accuracy.

通过新颖的多视图方法DeepShaRM，本研究提出了一种能够在未知自然光照条件下（即野外环境）重建无纹理、非兰伯特物体几何的几何重建方法。该方法通过引入深度反射率图估计网络，从当前几何估计的表面法线和输入的多视图图像中恢复相机视角的反射率图，并明确估计每个像素的置信度来处理全局光传输效应。然后，通过深度自遮蔽网络利用恢复的反射率图更新由符号距离函数表示的几何估计，通过这两者的交替迭代，并且避开了反射率和光照分解难题，该方法能够准确恢复这些复杂环境中的物体几何结构。通过对合成和真实数据的大量实验证明了该方法的准确性。

DeepShaRM: 未知光照下多视角形状和反射率图恢复