The mapping looked flat/skewed because rays were cast on the wrong side of the facade, world directions were mixed with room-local origins, and B/(B+d) UV crush / center mullions distorted the pre-projected atlas. Use per-window object space (window at z=+1 into -Z), Joost far-hit slab tests, bounded B/(B+d) sampling, outer sash only, and a matching perspective atlas bake. Co-authored-by: 西风逍遥游 <sunxfancy@gmail.com>