OmniSch: A Multimodal PCB Schematic Benchmark For Structured Diagram Visual Reasoning

TL;DR

OmniSch is a new benchmark for evaluating multimodal models on PCB schematic understanding, focusing on visual grounding, graph reasoning, geometric layout, and tool-augmented reasoning.

Contribution

It introduces the first comprehensive benchmark with real schematic diagrams and multiple tasks to assess LMMs' capabilities in electronic schematic interpretation.

Findings

Current LMMs show gaps in fine-grained grounding and graph parsing.

LMMs are inconsistent in global connectivity reasoning.

Visual exploration by LMMs is inefficient.

Abstract

Recent large multimodal models (LMMs) have made rapid progress in visual grounding, document understanding, and diagram reasoning tasks. However, their ability to convert Printed Circuit Board (PCB) schematic diagrams into machine-readable spatially weighted netlist graphs, jointly capturing component attributes, connectivity, and geometry, remains largely underexplored, despite such graph representations are the backbone of practical electronic design automation (EDA) workflows. To bridge this gap, we introduce OmniSch, the first comprehensive benchmark designed to assess LMMs on schematic understanding and spatial netlist graph construction. OmniSch contains 1,854 real-world schematic diagrams and includes four tasks: (1) visual grounding for schematic entities, with 109.9K grounded instances aligning 423.4K diagram semantic labels to their visual regions; (2) diagram-to-graph reasoning, understanding topological relationship among diagram elements; (3) geometric reasoning, constructing layout-dependent weights for each connection; and (4) tool-augmented agentic reasoning for visual search, invoking external tools to accomplish (1)-(3). Our results reveal substantial gaps of current LMMs in interpreting schematic engineering artifacts, including unreliable fine-grained grounding, brittle layout-to-graph parsing, inconsistent global connectivity reasoning and inefficient visual exploration.