# Unfold The World: Factorize 4D Properties in Reinforcing Spatial Reasoning > Source: > Published: 2026-09-08 01:00:12+00:00 Despite the remarkable prowess of Vision-Language Models (VLMs) in general multimodal tasks, they remain fundamentally ``flat'' when reasoning about the physical world. We argue that this spatial bottleneck stems from a profound dimensional mismatch: while VLMs are trained to interpret 2D projection