Deep Unrolling of Sparsity-Induced RDO for 3D Point Cloud Attribute Coding.

Do, Tam Thuc; Chou, Philip A; Cheung, Gene · IEEE Trans Image Process · 2026

basic_science · Level V

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Abstract

We study the problem of lossy attribute compression, given encoded 3D point cloud geometry available at the decoder, in a multi-resolution B-spline projection framework. A target continuous 3D attribute function is first projected onto a sequence of nested subspaces F<sup>(p)</sup> <sub>l0</sub> ⊆ · · · ⊆ F<sup>(p)</sup> <sub>L</sub> , where F<sup>(p)</sup> <sub>l</sub> is a family of functions spanned by a B-spline basis function of order p at a chosen scale and its integer shifts. The projected low-pass coefficients F<sup>∗</sup> <sub>l</sub> are computed via variable-complexity unrolling of a rate-distortion (RD) optimization algorithm into a feed-forward network, where the rate term is the sparsity-promoting ℓ<sub>1</sub>-norm. Thus, the projection operation is end-to-end differentiable. For a chosen coarse-to-fine predictor, the coefficients are then adjusted to account for the prediction from a lower-resolution to a higher-resolution, which is also optimized in a data-driven manner.