Nearly Making an Illegal Building Legal: Catching Vision AI's Single-Character Hallucination
Author: Kim Bo-geun What happens when a building code review AI confuses “4 floors or less” with “4 floors or more”? The height limit gets inverted, and an illegal building gets judged as legal. This article is about the journey to catch that single-character difference. The Problem: Tables Are Retrieved but Unreliable The building code review system analyzes building-related PDFs — district unit plans, design guidelines — to extract standards like building coverage ratio (BCR), floor area ratio (FAR), and height limits. The PDF preprocessing pipeline uses Docling to parse documents, chunk text, and generate embeddings for hybrid search (keyword + semantic). ...