DMD exponential cache for Hunyuan3D-2 mini sampling

Tencent's 0.6B image-to-3D model with a training-free exponential velocity forecaster wired into its flow-matching denoise loop. The cache computes the DiT on 1/interval of the steps and forecasts the velocity on the rest.

# clone + install (model weights downloaded separately from upstream)
git clone https://github.com/Archerkattri/hunyuan2-plus-plus.git
cd hunyuan2-plus-plus
pip install -r requirements.txt
pip install -e .
# weights: Tencent-Hunyuan/Hunyuan3D-2 (Hunyuan3D-2mini), not committed

Evidence

Base model	0.6B parameters — Hunyuan3D-2 mini shape generator (Hunyuan3DDiTFlowMatchingPipeline)
DMD interval-5 quality	0.793 F@0.05 on Toys4K (n = 10) vs 0.794 uncached baseline — within run noise
Skipped compute	(interval-1)/interval of DiT forward passes skipped; DiT computed on 1/interval of steps
DMD window floor	4 snapshots (3 pairs) minimum to fit a complex pole; below it falls back to Hermite
Default schedule	interval 5, first_enhance 2, history 5, max_order 2, sigma 0.5
CPU contract tests	5 passed — cache identity, timing and fallback accounting (CI green)

Media

HiCache++ integration diagram — Cache confined to the shape denoiser; DMD modes advance skipped-step velocity.

Demo input image — Demo input (assets/demo.png) for image-to-3D sampling.

Example multi-view front render from the upstream asset set.

Install & verify

# CPU contract tests (tests/test_hicache_dmd_adapter.py)
pytest tests/ -q
# expected: 5 passed (CI green per v0.1.1 release notes)

Limits

What this release does not claim (from the release notes):

GPU speedup validation and weight-gated demo cells. (No GPU hardware in this release.)

Family

Base model	Hunyuan3D-2, accelerated by the hicache-plus-plus forecast core
Same base	hunyuan2-plus
All 13 adapters	TRELLIS: faster-trellis, faster-trellis-plus-plus · TRELLIS.2: fast-trellis2, hermit-trellis2, hermit-trellis2-plus-plus · Hunyuan3D-2: hunyuan2-plus, hunyuan2-plus-plus · Hunyuan3D-2.1: hunyuan2.1-plus, hunyuan2.1-plus-plus · SAM: sam3d-plus, sam3d-plus-plus, fastsam3d-plus, fastsam3d-plus-plus
External	Paper arXiv:2501.12202