Level of detail has been widely used in interactive computer graphics. In current industrial 3D modeling pipelines, artists rely on commercial software to generate highly detailed models with UV maps and then bake textures for low-poly counterparts. In these pipelines, each step is performed separately, leading to unsatisfactory visual appearances for low polygon count models. Moreover, existing texture baking techniques assume the low-poly mesh has a small geometric difference from the high-poly, which is often not true in practice, especially with extremely low poly count models.

To alleviate the visual discrepancy of the low-poly mesh, we propose to jointly optimize UV mappings during texture baking, allowing for low-poly models to faithfully replicate the appearance of the high-poly even with large geometric differences. We formulate the optimization within a differentiable rendering framework, allowing the automatic adjustment of texture regions to encode appearance information. To compensate for view parallax when two meshes have large geometric differences, we introduce a spherical harmonic parallax mapping, which uses spherical harmonic functions to modulate per-texel UV coordinates based on the view direction. We evaluate the effectiveness and robustness of our approach on a dataset composed of online downloaded models, with varying complexities and geometric discrepancies. Our method achieves superior quality over state-of-the-art techniques and commercial solutions.

细节层次已广泛应用于交互式计算机图形学中。在当前的工业 3D 建模流程中，艺术家依靠商业软件使用 UV 贴图生成高度详细的模型，然后为低多边形模型烘焙纹理。在这些管道中，每个步骤都是单独执行的，导致低多边形计数模型的视觉外观不令人满意。此外，现有的纹理烘焙技术假设低多边形网格与高多边形网格具有较小的几何差异，但这在实践中通常是不正确的，特别是对于极低多边形计数模型。

为了减轻低多边形网格的视觉差异，我们建议在纹理烘焙过程中联合优化 UV 映射，使低多边形模型即使在几何差异较大的情况下也能忠实地复制高多边形的外观。我们在可微渲染框架内制定优化，允许自动调整纹理区域以编码外观信息。为了补偿两个网格具有较大几何差异时的视图视差，我们引入了球谐视差映射，它使用球谐函数根据视图方向调制每纹理像素的 UV 坐标。我们在由在线下载的模型组成的数据集上评估我们的方法的有效性和鲁棒性，这些模型具有不同的复杂性和几何差异。