BlockFusion：使用潜在三平面外推扩展的可扩展3D场景生成

BlockFusion: Expandable 3D Scene Generation using Latent Tri-plane Extrapolation

January 30, 2024

作者: Zhennan Wu, Yang Li, Han Yan, Taizhang Shang, Weixuan Sun, Senbo Wang, Ruikai Cui, Weizhe Liu, Hiroyuki Sato, Hongdong Li, Pan Ji

cs.AI

摘要

我们提出了BlockFusion，这是一种基于扩散的模型，可以将3D场景生成为单位块，并无缝地将新块整合到场景中。BlockFusion使用从完整3D场景网格中随机裁剪的3D块数据集进行训练。通过逐块拟合，所有训练块都被转换为混合神经场：一个包含几何特征的三平面，然后是用于解码有符号距离值的多层感知器（MLP）。采用变分自动编码器将三平面压缩为潜在三平面空间，然后执行去噪扩散过程。对潜在表示应用扩散允许高质量和多样化的3D场景生成。在生成过程中扩展场景时，只需附加空块以与当前场景重叠，并外推现有的潜在三平面以填充新块。外推是通过在去噪迭代期间使用来自重叠三平面的特征样本来调节生成过程完成的。潜在三平面外推产生语义和几何上有意义的过渡，与现有场景和谐融合。使用2D布局调节机制来控制场景元素的放置和排列。实验结果表明，BlockFusion能够生成多样化、几何一致且无限大的高质量形状的3D场景，适用于室内和室外场景。

English

We present BlockFusion, a diffusion-based model that generates 3D scenes as unit blocks and seamlessly incorporates new blocks to extend the scene. BlockFusion is trained using datasets of 3D blocks that are randomly cropped from complete 3D scene meshes. Through per-block fitting, all training blocks are converted into the hybrid neural fields: with a tri-plane containing the geometry features, followed by a Multi-layer Perceptron (MLP) for decoding the signed distance values. A variational auto-encoder is employed to compress the tri-planes into the latent tri-plane space, on which the denoising diffusion process is performed. Diffusion applied to the latent representations allows for high-quality and diverse 3D scene generation. To expand a scene during generation, one needs only to append empty blocks to overlap with the current scene and extrapolate existing latent tri-planes to populate new blocks. The extrapolation is done by conditioning the generation process with the feature samples from the overlapping tri-planes during the denoising iterations. Latent tri-plane extrapolation produces semantically and geometrically meaningful transitions that harmoniously blend with the existing scene. A 2D layout conditioning mechanism is used to control the placement and arrangement of scene elements. Experimental results indicate that BlockFusion is capable of generating diverse, geometrically consistent and unbounded large 3D scenes with unprecedented high-quality shapes in both indoor and outdoor scenarios.