  Contrastive learning has emerged as a promising paradigm for 3D open-world
understanding, i.e., aligning point cloud representation to image and text
embedding space individually. In this paper, we introduce MixCon3D, a simple
yet effective method aiming to sculpt holistic 3D representation in contrastive
language-image-3D pre-training. In contrast to point cloud only, we develop the
3D object-level representation from complementary perspectives, e.g.,
multi-view rendered images with the point cloud. Then, MixCon3D performs
language-3D contrastive learning, comprehensively depicting real-world 3D
objects and bolstering text alignment. Additionally, we pioneer the first
thorough investigation of various training recipes for the 3D contrastive
learning paradigm, building a solid baseline with improved performance.
Extensive experiments conducted on three representative benchmarks reveal that
our method significantly improves over the baseline, surpassing the previous
state-of-the-art performance on the challenging 1,156-category Objaverse-LVIS
dataset by 5.7%. The versatility of MixCon3D is showcased in applications such
as text-to-3D retrieval and point cloud captioning, further evidencing its
efficacy in diverse scenarios. The code is available at
https://github.com/UCSC-VLAA/MixCon3D.
