做具身智能或空间推理的开发者会发现，当前VLMs的数值输出可能只是“看起来对”，实际缺乏空间感知——这项研究用严谨实验戳破了这个盲区，值得关注。
该研究通过SpaceNum框架系统评估了视觉语言模型（VLMs）在空间数值理解上的表现，包括动态探索和静态布局两种场景。实验发现，当前VLMs在将视觉空间结构与语言数值表示进行映射时，表现接近随机猜测，严重依赖浅层空间线索。模型难以建立稳定的坐标感知表示，也无法从视觉观察中抽象出结构化空间布局。即使加入显式推理或微调，提升也有限。这项研究揭示了VLMs在具身环境中输出数值（如动作幅度、空间坐标）时，可能并未真正理解其空间含义。
SPACENUM: Revisiting Spatial Numerical Understanding in VLMs
Vision-Language Models (VLMs) are increasingly deployed in embodied environments, where they need produce numerical outputs such as action magnitudes and spatial coordinates. Although these numbers appear meaningful, it remains unclear whether these numerical outputs are genuinely grounded in spatial perception. Therefore, in this work, we revisit spatial numerical understanding through SpaceNum, a unified framework that captures two complementary settings: numbers as dynamic transitions during spatial exploration, and numbers as static layouts in spatial reasoning. We formulate two bidirectional tasks, Num2Space and Space2Num, to evaluate how well VLMs map between vision-side spatial structure and language-side numerical representations. We systematically study whether current VLMs truly understand numerical values in spatial settings. Across dynamic transitions and static layouts, we find that models largely fail to ground numbers in spatial meaning and often perform close to random guess. Through error analysis, reasoning trace analysis, and controlled interventions, we show that current VLMs rely heavily on shallow spatial cues, struggle to build stable coordinate-aware representations, and fail to abstract structured spatial layouts from visual observations. We further show that explicit reasoning provides only marginal gains, while tuning can partially improve spatial numerical understanding and transfer to external spatial reasoning benchmarks.