这篇论文用TriViewBench测了18个多模态模型，发现它们都在多视图推理上崩得厉害，CoT也救不了。想了解当前MLLM的结构推理极限，可以看看。
TriViewBench 是一个基于合成3D场景的受控多视图视觉推理基准，包含1,923个场景和超过14K个问答对，分为4个复杂度级别和3个推理类别：局部决策、物体计数和全局恢复。评估18个开源和闭源MLLMs发现，所有模型能力排序一致（局部决策>物体计数>全局恢复），且随着复杂度增加性能单调下降：局部决策下降12.11%，物体计数下降59.14%，全局恢复骤降80.02%。错误分析表明，单视图任务中因遮挡导致欠计数，多视图任务因跨视角身份混淆导致过计数。Chain-of-Thought提示几乎无收益（Δ=-0.16%），表明瓶颈在于跨视角空间表示而非推理策略。
TriViewBench: Controlled Complexity Scaling for Multi-View Structural Reasoning in MLLMs
Multimodal Large Language Models (MLLMs) demonstrate strong performance on standard visual question answering benchmarks, yet their scalability under controlled structural complexity remains poorly understood. We introduce TriViewBench, a controlled three-view visual reasoning benchmark constructed from synthetic 3D scenes with explicitly parameterized object count and occlusion. The benchmark contains 1,923 scenes and over 14K Question-Answer (QA) pairs organized into four complexity levels and three reasoning categories: Local Decision, Object Counting, and Global Recovery. We evaluate 18 open- and closed-source MLLMs under a unified prompting protocol. All 18 models exhibit an identical capability hierarchy without exception (Local Decision > Object Counting > Global Recovery), and performance degrades monotonically with complexity: Local Decision tasks decline modestly (12.11% relative drop), while Object Counting degrades substantially (59.14%) and Global Recovery collapses severely (80.02%). Error analysis on Object Counting reveals two mechanistically independent failure modes: single-view tasks are dominated by undercounting due to occlusion blindness, whereas the multi-view task reverses to overcounting due to cross-view identity confusion. Chain-of-Thought (CoT) prompting yields near-zero overall benefit ($Δ= -0.16\%$) and its effect on Global Recovery is strongly capability-gated, suggesting that the bottleneck lies in cross-view spatial representation rather than reasoning strategy. These findings reveal fundamental scalability limitations in current MLLMs and position TriViewBench as a controlled diagnostic framework for analyzing structural reasoning failures.