Zero-Shot Vehicle Model Recognition via Text-Based Retrieval-Augmented Generation
Wei-Chia Chang, Yan-Ann Chen
TL;DR
This work tackles zero-shot vehicle make–model recognition (VMMR) by moving recognition from the image domain to text. It introduces a retrieval-augmented generation (RAG) pipeline that first converts each vehicle image into a descriptive text via a vision–language model, then retrieves related textual entries from a dynamic database and uses a language model to reason over the combination to predict the make and model. The authors demonstrate that this text-centric approach, which grounds LM reasoning in retrieved evidence, substantially outperforms a CLIP baseline on 10 newly released car models, achieving about $0.37$ accuracy versus $0.21$ for CLIP (roughly a 16 percentage point gain). The method is lightweight, relies on open-source models, and supports rapid updates by simply adding textual descriptions of new vehicles, making it practical for scalable, edge-ready VMMR in smart-city contexts.
Abstract
Vehicle make and model recognition (VMMR) is an important task in intelligent transportation systems, but existing approaches struggle to adapt to newly released models. Contrastive Language-Image Pretraining (CLIP) provides strong visual-text alignment, yet its fixed pretrained weights limit performance without costly image-specific finetuning. We propose a pipeline that integrates vision language models (VLMs) with Retrieval-Augmented Generation (RAG) to support zero-shot recognition through text-based reasoning. A VLM converts vehicle images into descriptive attributes, which are compared against a database of textual features. Relevant entries are retrieved and combined with the description to form a prompt, and a language model (LM) infers the make and model. This design avoids large-scale retraining and enables rapid updates by adding textual descriptions of new vehicles. Experiments show that the proposed method improves recognition by nearly 20% over the CLIP baseline, demonstrating the potential of RAG-enhanced LM reasoning for scalable VMMR in smart-city applications.
