
a Relightable Information-Shared Signed Distance Field for Glossy Object Inverse Rendering面向高光物体逆渲染的可重打光、信息共享符号距离场(a Relightable Information-Shared Signed Distance Field)
Deheng Zhang1,2*, Jingyu Wang1*, Shaofei Wang1, Marko Mihajlovic1, Sergey Prokudin1, Hendrik P.A. Lensch2, Siyu Tang1
1ETH Zürich 2University of Tübingen · *equal contribution*共同一作
Split-sum shading (the appearance model RISE-SDF uses), rendered live in your browser under a rotating environment map.用 split-sum 着色(RISE-SDF 使用的外观模型)在浏览器里实时渲染,环境光在缓慢旋转。
→ / Space: next ← back L: 中 / EN F: fullscreen O: contents→ / 空格:下一步 ← 上一步 L:中 / EN F:全屏 O:目录
Given multi-view images and camera poses of an object, recover what produced them, so the object can be rendered again under any new light.给定一个物体的多视角图像和相机位姿,恢复生成这些图像的因素,从而在任意新光照下重新渲染它。
signed distance field \(s(\mathbf x)\); surface \(s=0\), normal \(\mathbf n\)符号距离场 \(s(\mathbf x)\);表面 \(s=0\),法线 \(\mathbf n\)
albedo \(\mathbf a\), metallic \(m\), roughness \(\rho\) of a simplified Disney BRDF简化 Disney BRDF 的反照率 \(\mathbf a\)、金属度 \(m\)、粗糙度 \(\rho\)
a distant environment map \(L\)远处的环境贴图 \(L\)
Glossy objects are the hard case: a mirror-like surface shows its surroundings, not itself, so reflections are easily baked into the texture or the shape.高光物体是难点:镜面一样的表面映出的是周围环境而不是自己,反射很容易被错当成纹理或几何。
Inverse-rendering methods for glossy objects, as compared in the paper. Click a row to see its relighting of the toaster.论文对比的高光物体逆渲染方法。点击一行,查看它对烤面包机的重打光结果。
| Method方法 | Representation表示 | PB | E2ER | Train训练 | Relighting failure (paper)重打光的问题(论文所述) |
|---|
PB: physically based BRDF. E2ER: end-to-end relightable; NeRO and ENVIDR need extra steps per new light (a Blender export, or training an MLP to hold the environment map). Training times from the paper's Table 1.PB:基于物理的 BRDF。E2ER:端到端可重打光;NeRO 和 ENVIDR 每换一种光照都要额外步骤(导出到 Blender,或训练一个 MLP 来存环境贴图)。训练时间来自论文表 1。


And no glossy dataset had ground-truth material and relighting, so material quality could not be measured.此外,没有任何高光数据集提供材质和重打光的真值,材质好坏无法定量评测。

A neural SDF (NeuS on a progressive hash grid) with a reflection-aware radiance field: diffuse, specular and blend MLPs.神经 SDF(渐进式哈希网格上的 NeuS),配一个感知反射的辐射场:漫反射、高光和混合三个 MLP。
The same MLP heads also predict albedo and metallic; split-sum PBR with a cube-mipmap environment; trained jointly with the radiance field.同一组 MLP 头同时预测反照率和金属度;用 split-sum PBR 和立方体 mipmap 环境光,与辐射场联合训练。
Training: an MLP predicts the indirect specular light. Relighting: a second split-sum traces one bounce.训练时:一个 MLP 预测高光的间接光。重打光时:用第二次 split-sum 追踪一次反弹。
Five glossy scenes with ground-truth albedo, roughness and relighting under nine environment maps.五个高光场景,提供反照率、粗糙度的真值,以及九张环境贴图下的重打光真值。
NeuS turns the SDF along a camera ray into opacities, so a surface can be learned from images alone. Sharpen the density and the weights collapse onto the first surface.NeuS 把相机光线上的 SDF 转成不透明度,于是只用图像就能学出表面。把密度调尖,权重会集中到第一个表面上。
\(1/\sigma\) is learned and shrinks during training. RISE-SDF predicts \(s\) and a feature \(\boldsymbol\beta\) from a progressive hash grid, with Eikonal and curvature losses.\(1/\sigma\) 是可学习的,训练中会变小。RISE-SDF 用渐进式哈希网格预测 \(s\) 和特征 \(\boldsymbol\beta\),并加 Eikonal 和曲率损失。
Shading needs an integral over the hemisphere. Split-sum replaces it with two lookups. Drag the sphere to turn the light.着色需要在半球上积分。split-sum 把它换成两次查表。拖动小球可以旋转光照。
Demo: GGX lobes; the 2D LUT is replaced by Lazarov's analytic fit. Not the paper's code.演示:GGX 波瓣;二维查找表用 Lazarov 的解析拟合代替。并非论文代码。
Both mix diffuse and specular. One MLP outputs the blend weight and the metallic value.两者都在混合漫反射和高光。同一个 MLP 同时输出混合权重和金属度。
Both are view-independent and low-entropy. One MLP outputs the diffuse colour and the albedo.两者都与视角无关、信息量低。同一个 MLP 同时输出漫反射颜色和反照率。
Geometry keeps training. The radiance-field loss stays on in stage 2, unlike NeRO, InvRender and NRTF, which freeze geometry before material estimation.几何继续训练。阶段二仍保留辐射场损失;NeRO、InvRender、NRTF 则在估计材质前就冻结了几何。
Toaster, with and without information sharing. Without it, the model is shown at 5k iterations (the full model's material-optimization time) and at 15k (its geometry time).烤面包机,有无信息共享的对比。无共享的模型分别在 5k 次迭代(完整模型优化材质的时长)和 15k 次迭代(完整模型优化几何的时长)时展示。












Average over the five synthetic scenes (paper Table 1): without sharing → full model.五个合成场景的平均(论文表 1):无共享 → 完整模型。
Training time: 2 h without sharing, 2.5 h for the full model.训练时间:无共享 2 小时,完整模型 2.5 小时。
A glossy surface also reflects the object itself. Drag the hit point along the floor.高光表面还会映出物体自身。沿地面拖动交点。
Cheap: the secondary ray queries only the geometry MLP, plus one indirect-colour query at \(\hat{\mathbf x}\): \(M+1\) queries, against \(2N\) for NeRO and \(4M\) for TensoIR/ENVIDR-style marching (with one density and three colour MLPs).开销小:次级光线只查询几何 MLP,再在 \(\hat{\mathbf x}\) 处查询一次间接颜色:共 \(M+1\) 次;NeRO 要 \(2N\) 次,TensoIR/ENVIDR 式的二次行进要 \(4M\) 次(一个密度 MLP 加三个颜色 MLP 时)。
Toaster relit with the fireplace environment map. Bottom row: the boxed region, enlarged.用壁炉环境贴图重打光的烤面包机。下排是框中区域的放大。








relighting PSNR of the full model, averaged over the five scenes.完整模型的重打光 PSNR,五个场景平均。
No indirect MLP: reflections of the object on itself look less realistic.去掉间接光 MLP:物体映在自身上的反射不够真实。
No second split-sum: the indirect MLP, trained under the training light, gives unnatural contrast under a new one.去掉第二次 split-sum:间接光 MLP 是在训练光照下学的,换了光照就出现不自然的对比。
Five Shiny Blender objects (teapot, coffee, muscle car, toaster, helmet), re-shaded so that data and model use the same BRDF.取 Shiny Blender 的五个物体(茶壶、咖啡、肌肉车、烤面包机、头盔),重新设置着色器,使数据与模型使用同一种 BRDF。
| Dataset数据集 | Material材质 | Relighting重打光 | # env maps环境贴图数 | Shiny高光 |
|---|---|---|---|---|
| NeRF Synthetic | ✗ | ✗ | 0 | ✗ |
| Shiny Blender | ✗ | ✗ | 0 | ✓ |
| NeRO Synthetic | ✗ | ✓ | 3 | ✓ |
| NeRFactor Synthetic | ✓ | ✓ | 8 | ✗ |
| TensoIR Synthetic | ✓ | ✓ | 8 | ✗ |
| Ours本文 | ✓ | ✓ | 9 | ✓ |






Top: a relighting ground truth. Bottom: ground-truth albedo (left half) and roughness (right half).上:重打光真值。下:反照率真值(左半)和粗糙度真值(右半)。
Averages over the five synthetic scenes (paper Table 1). The second split-sum only acts at relighting, so that variant has relighting numbers only.五个合成场景的平均(论文表 1)。第二次 split-sum 只在重打光时起作用,所以该变体只有重打光的数字。
Trained 4 h with ground-truth object masks; meshes from marching cubes at 512³.训练 4 小时,使用物体真值掩码;网格由 512³ 的 marching cubes 提取。
Geometry: second best. Chamfer distance averages 0.0032 against NeRO's 0.0019; NDR, NDRMC and ours use ground-truth masks.几何:第二好。平均 Chamfer 距离 0.0032,NeRO 为 0.0019;NDR、NDRMC 和本文用了真值掩码。
Material falls short here: the distant-light assumption breaks. The masked-out plate causes near-field indirect light, and the photographer's reflection is not modelled.材质在这里不够好:远处光源的假设不成立。被掩掉的底盘带来近场间接光,拍摄者自己的反射也没有建模。
No transparent or anisotropic materials.处理不了透明或各向异性的材质。
Weaker under point lights, and shadows can be mistaken for geometry (right). A shadow cache after stage 1, as in GS-IR, is a possible fix.点光源下效果较差,阴影还可能被误当成几何(右图)。可行的改进是像 GS-IR 那样在阶段一之后缓存阴影。
Light, material and geometry trade off; the material can still be far off in some cases.光照、材质和几何之间可以互相抵消;某些情况下材质仍会偏离很多。
TensoIR synthetic set (lego, hotdog, armadillo, ficus), averages from the paper's supplementary.TensoIR 合成数据集(lego、hotdog、armadillo、ficus),数字为论文补充材料中的平均值。

Paper's failure example: the shadow is explained by geometry, which leaves artifacts.论文中的失败例子:阴影被解释成几何,留下伪影。
RISE-SDF reconstructs glossy objects into geometry, material and lighting that can be relit end to end, with no Blender export and no per-light training.RISE-SDF 把高光物体重建成可端到端重打光的几何、材质和光照,不需要导出到 Blender,也不需要为每种光照单独训练。
Share what the two branches have in common. Blend weight ↔ metallic and diffuse colour ↔ albedo come from the same MLPs, which stabilizes material and geometry.让两个分支共享共同的东西。混合权重 ↔ 金属度、漫反射颜色 ↔ 反照率由同一组 MLP 输出,材质和几何都因此更稳定。
Split-sum everywhere, including one secondary bounce for relighting: noise-free and faster than Monte Carlo.处处用 split-sum,重打光时的一次二次反弹也是:没有噪声,比 Monte Carlo 更快。
Measure material, not just pictures. A glossy dataset with ground-truth albedo, roughness and relighting.评测材质,而不只是评测图像。一个带反照率、粗糙度和重打光真值的高光数据集。