LLMFormer: Large Language Model for Open-Vocabulary Semantic Segmentation

Open-vocabulary (OV) semantic segmentation has attracted increasing attention in recent years, which aims to recognize objects in an open class set for real-world applications. While prior OV semantic segmentation approaches have relied on additional semantic knowledge derived from vision-language (VL) pre-training, such as the popular CLIP model, this paper introduces a novel paradigm by harnessing the unprecedented capabilities of large language models (LLMs). Inspired by recent breakthroughs in LLMs that provide a richer knowledge base compared to traditional vision-language pre-training, our proposed methodology capitalizes on the vast knowledge embedded within LLMs for OV semantic segmentation. Particularly, we partition LLM knowledge into object, attribute, and relation priors, and propose three novel attention modules-semantic, scaled visual, and relation attentions, to utilize the LLM priors. Extensive experiments are conducted on common benchmarks including ADE20K (847 classes) and Pascal Context (459 classes). The results show that our model outperforms previous state-of-the-art (SoTA) methods by up to 7.2% absolute. Moreover, unlike previous VL-pre-training-based works, our method can even predict OV segmentation results without target candidate classes.