PGT用低成本数据生成解决了MLLM细粒度视觉理解的瓶颈，做多模态模型训练或评估的团队可以直接用这个框架提升定位能力，值得一试。
多模态大语言模型在细粒度视觉理解上仍有不足。研究者提出PGT框架，通过在图像上叠加几何基元生成密集监督信号，分离视觉定位与语义先验。实验显示，在LLaVA-v1.5-Instruct上加入PGT数据后，What'sUp基准提升20%，CV-Bench-2D提升13.3%，且不影响通用感知能力。在先进MLLM上微调也带来最高8.3%的提升。结果表明，许多空间推理缺陷源于监督信号不足，而非架构或分辨率限制。
PGT: Procedurally Generated Tasks for improving visual grounding in MLLMs
Despite remarkable progress in Multimodal Large Language Models (MLLMs), these models still struggle with fine-grained understanding tasks. In this work, we propose Procedurally Generated Tasks (PGT), a simple data-driven framework that serves a dual purpose: inducing fine-grained visual understanding and acting as a low-cost diagnostic tool to identify the source of perception failures. By overlaying unambiguous geometric primitives on images, PGT generate additional dense supervision that disentangles visual grounding capability from semantic priors. Extensive experiments on relational, quantitative, and 3D/depth understanding benchmarks show that PGT yields remarkable gains across diverse architectures. Instruction tuning MLLMs on LLaVA-v1.5-Instruct augmented with PGT data results in improvements of up to +20% on the What'sUp benchmark and +13.3% on CV-Bench-2D, while maintaining general perception capabilities. Moreover, finetuning state-of-the-art MLLMs on PGT data leads to boosts of up to +5.5% on What'sUp and +8.3% on CV-Bench-2D. These findings demonstrate that PGT effectively address the bottleneck of fine-grained perception, revealing that many spatial reasoning deficits stem from inadequate supervision signals rather than inherent architectural or resolution limitations.