Surface meshes associated with diffuse texture or color attributes are becoming popular multimedia contents. They provide a high degree of realism and allow six degrees of freedom (6DoF) interactions in immersive virtual reality environments. Just like other types of multimedia, 3D meshes are subject to a wide range of processing, e.g., simplification and compression, which result in a loss of quality of the final rendered scene. Thus, both subjective studies and objective metrics are needed to understand and predict this visual loss. In this work, we introduce a large dataset of 480 animated meshes with diffuse color information, and associated with perceived quality judgments. The stimuli were generated from 5 source models subjected to geometry and color distortions. Each stimulus was associated with 6 hypothetical rendering trajectories (HRTs): combinations of 3 viewpoints and 2 animations. A total of 11520 quality judgments (24 per stimulus) were acquired in a subjective experiment conducted in virtual reality. The results allowed us to explore the influence of source models, animations and viewpoints on both the quality scores and their confidence intervals. Based on these findings, we propose the first metric for quality assessment of 3D meshes with diffuse colors, which works entirely on the mesh domain. This metric incorporates perceptually-relevant curvature-based and color-based features. We evaluate its performance, as well as a number of Image Quality Metrics (IQMs), on two datasets: ours and a dataset of distorted textured meshes. Our metric demonstrates good results and a better stability than IQMs. Finally, we investigated how the knowledge of the viewpoint (i.e., the visible parts of the 3D model) may improve the results of objective metrics.

中文翻译：

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虚拟现实中具有漫反射颜色的 3D 网格的视觉质量：主观和客观评估

与漫反射纹理或颜色属性相关的表面网格正在成为流行的多媒体内容。它们提供了高度的真实感，并允许在沉浸式虚拟现实环境中进行六自由度 (6DoF) 交互。就像其他类型的多媒体一样，3D 网格要经过广泛的处理，例如简化和压缩，这会导致最终渲染场景的质量下降。因此，需要主观研究和客观指标来理解和预测这种视觉损失。在这项工作中，我们引入了一个包含 480 个具有漫反射颜色信息并与感知质量判断相关联的动画网格的大型数据集。刺激是从 5 个受到几何和颜色失真影响的源模型中生成的。每个刺激都与 6 个假设的渲染轨迹 (HRT) 相关联：3 个视点和 2 个动画的组合。在虚拟现实中进行的主观实验中，总共获得了 11520 个质量判断（每个刺激 24 个）。结果使我们能够探索源模型、动画和观点对质量分数及其置信区间的影响。基于这些发现，我们提出了第一个对具有漫反射颜色的 3D 网格进行质量评估的指标，该指标完全适用于网格域。该指标结合了感知相关的基于曲率和基于颜色的特征。我们在两个数据集上评估其性能以及许多图像质量指标 (IQM)：我们的数据集和扭曲纹理网格的数据集。我们的指标显示出比 IQM 更好的结果和更好的稳定性。最后，我们调查了观点的知识（即，